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\n  \n 2022\n \n \n (1)\n \n \n
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\n \n\n \n \n \n \n \n \n Measurement-based generation and preservation of cat and grid states within a continuous-variable cluster state.\n \n \n \n \n\n\n \n Eaton, M.; González-Arciniegas, C.; Alexander, R. N.; Menicucci, N. C.; and Pfister, O.\n\n\n \n\n\n\n Quantum, 6: 769. July 2022.\n \n\n\n\n
\n\n\n\n \n \n \"Measurement-basedPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Eaton2022measurementbased,\n  doi = {10.22331/q-2022-07-20-769},\n  url = {https://doi.org/10.22331/q-2022-07-20-769},\n  title = {Measurement-based generation and preservation of cat and grid states within a continuous-variable cluster state},\n  author = {Eaton, Miller and Gonz{\\'{a}}lez-Arciniegas, Carlos and Alexander, Rafael N. and Menicucci, Nicolas C. and Pfister, Olivier},\n  journal = {{Quantum}},\n  issn = {2521-327X},\n  publisher = {{Verein zur F{\\"{o}}rderung des Open Access Publizierens in den Quantenwissenschaften}},\n  volume = {6},\n  pages = {769},\n  month = jul,\n  year = {2022}\n}\n\n
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\n  \n 2021\n \n \n (7)\n \n \n
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\n \n\n \n \n \n \n \n \n Time-Domain-Multiplexed Measurement-Based Quantum Operations with 25-MHz Clock Frequency.\n \n \n \n \n\n\n \n Asavanant, W.; Charoensombutamon, B.; Yokoyama, S.; Ebihara, T.; Nakamura, T.; Alexander, R. N.; Endo, M.; Yoshikawa, J.; Menicucci, N. C.; Yonezawa, H.; and Furusawa, A.\n\n\n \n\n\n\n Phys. Rev. Appl., 16: 034005. Sep 2021.\n \n\n\n\n
\n\n\n\n \n \n \"Time-Domain-MultiplexedPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{PhysRevApplied.16.034005,\n  title = {Time-Domain-Multiplexed Measurement-Based Quantum Operations with 25-MHz Clock Frequency},\n  author = {Asavanant, Warit and Charoensombutamon, Baramee and Yokoyama, Shota and Ebihara, Takeru and Nakamura, Tomohiro and Alexander, Rafael N. and Endo, Mamoru and Yoshikawa, Jun-ichi and Menicucci, Nicolas C. and Yonezawa, Hidehiro and Furusawa, Akira},\n  journal = {Phys. Rev. Appl.},\n  volume = {16},\n  issue = {3},\n  pages = {034005},\n  numpages = {10},\n  year = {2021},\n  month = {Sep},\n  publisher = {American Physical Society},\n  doi = {10.1103/PhysRevApplied.16.034005},\n  url = {https://link.aps.org/doi/10.1103/PhysRevApplied.16.034005}\n}\n\n
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\n \n\n \n \n \n \n \n \n Streamlined quantum computing with macronode cluster states.\n \n \n \n \n\n\n \n Walshe, B. W.; Alexander, R. N.; Menicucci, N. C.; and Baragiola, B. Q.\n\n\n \n\n\n\n Phys. Rev. A, 104: 062427. Dec 2021.\n \n\n\n\n
\n\n\n\n \n \n \"StreamlinedPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{PhysRevA.104.062427,\n\tabstract = {Continuous-variable cluster states allow for fault-tolerant measurement-based quantum computing when used in tandem with the Gottesman-Kitaev-Preskill (GKP) encoding of a qubit into a bosonic mode. For quad-rail-lattice macronode cluster states, whose construction is defined by a fixed, low-depth beam splitter network, we show that a Clifford gate and GKP error correction can be simultaneously implemented in a single teleportation step. We give explicit recipes to realize the Clifford generating set, and we calculate the logical gate-error rates given finite squeezing in the cluster-state and GKP resources. We find that logical error rates of 10<sup>-2</sup>--10<sup>-3</sup>, compatible with the thresholds of topological codes, can be achieved with squeezing of 11.9--13.7 dB. The protocol presented eliminates noise present in prior schemes and puts the required squeezing for fault tolerance in the range of current state-of-the-art optical experiments. Finally, we show how to produce distillable GKP magic states directly within the cluster state.},\n\tauthor = {Walshe, Blayney W. and Alexander, Rafael N. and Menicucci, Nicolas C. and Baragiola, Ben Q.},\n\tdate-added = {2022-01-14 10:15:13 +1100},\n\tdate-modified = {2022-01-14 10:23:56 +1100},\n\tdoi = {10.1103/PhysRevA.104.062427},\n\tissue = {6},\n\tjournal = {Phys. Rev. A},\n\tmonth = {Dec},\n\tnumpages = {15},\n\tpages = {062427},\n\tpublisher = {American Physical Society},\n\ttitle = {Streamlined quantum computing with macronode cluster states},\n\turl = {https://link.aps.org/doi/10.1103/PhysRevA.104.062427},\n\tvolume = {104},\n\tyear = {2021},\n\tBdsk-Url-1 = {https://link.aps.org/doi/10.1103/PhysRevA.104.062427},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.104.062427}}\n\n
\n
\n\n\n
\n Continuous-variable cluster states allow for fault-tolerant measurement-based quantum computing when used in tandem with the Gottesman-Kitaev-Preskill (GKP) encoding of a qubit into a bosonic mode. For quad-rail-lattice macronode cluster states, whose construction is defined by a fixed, low-depth beam splitter network, we show that a Clifford gate and GKP error correction can be simultaneously implemented in a single teleportation step. We give explicit recipes to realize the Clifford generating set, and we calculate the logical gate-error rates given finite squeezing in the cluster-state and GKP resources. We find that logical error rates of 10-2–10-3, compatible with the thresholds of topological codes, can be achieved with squeezing of 11.9–13.7 dB. The protocol presented eliminates noise present in prior schemes and puts the required squeezing for fault tolerance in the range of current state-of-the-art optical experiments. Finally, we show how to produce distillable GKP magic states directly within the cluster state.\n
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\n \n\n \n \n \n \n \n \n Hidden qubit cluster states.\n \n \n \n \n\n\n \n Pantaleoni, G.; Baragiola, B. Q.; and Menicucci, N. C.\n\n\n \n\n\n\n Physical Review A, 104(1). Jul 2021.\n \n\n\n\n
\n\n\n\n \n \n \"HiddenPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{Pantaleoni_2021,\n\tabstract = {Continuous-variable cluster states (CVCSs) can be supplemented with Gottesman-Kitaev-Preskill (GKP) states to form a hybrid cluster state with the power to execute universal, fault-tolerant quantum computing in a measurement-based fashion. As the resource states that comprise a hybrid cluster state are of a very different nature, a natural question arises: Why do GKP states interface so well with CVCSs? To answer this question, we apply the recently introduced subsystem decomposition of a bosonic mode, which divides a mode into logical and gauge-mode subsystems, to three types of cluster state: CVCSs, GKP cluster states, and hybrid CV-GKP cluster states. We find that each of these contains a "hidden" qubit cluster state across their logical subsystems, which lies at the heart of their utility for measurement-based quantum computing. To complement the analytical approach, we introduce a simple graphical description of these CV-mode cluster states that depicts precisely how the hidden qubit cluster states are entangled with the gauge modes, and we outline how these results would extend to the case of finitely squeezed states. This work provides important insight that is both conceptually satisfying and helps to address important practical issues like when a simpler resource (such as a Gaussian state) can stand in for a more complex one (like a GKP state), leading to more efficient use of the resources available for CV quantum computing.},\n\tauthor = {Pantaleoni, Giacomo and Baragiola, Ben Q. and Menicucci, Nicolas C.},\n\tdate-added = {2021-09-23 14:35:55 +1000},\n\tdate-modified = {2021-09-23 14:35:55 +1000},\n\tdoi = {10.1103/physreva.104.012431},\n\tissn = {2469-9934},\n\tjournal = {Physical Review A},\n\tmonth = {Jul},\n\tnumber = {1},\n\tpublisher = {American Physical Society (APS)},\n\ttitle = {Hidden qubit cluster states},\n\turl = {http://dx.doi.org/10.1103/PhysRevA.104.012431},\n\tvolume = {104},\n\tyear = {2021},\n\tBdsk-Url-1 = {http://dx.doi.org/10.1103/PhysRevA.104.012431},\n\tBdsk-Url-2 = {http://dx.doi.org/10.1103/physreva.104.012431}}\n\n
\n
\n\n\n
\n Continuous-variable cluster states (CVCSs) can be supplemented with Gottesman-Kitaev-Preskill (GKP) states to form a hybrid cluster state with the power to execute universal, fault-tolerant quantum computing in a measurement-based fashion. As the resource states that comprise a hybrid cluster state are of a very different nature, a natural question arises: Why do GKP states interface so well with CVCSs? To answer this question, we apply the recently introduced subsystem decomposition of a bosonic mode, which divides a mode into logical and gauge-mode subsystems, to three types of cluster state: CVCSs, GKP cluster states, and hybrid CV-GKP cluster states. We find that each of these contains a \"hidden\" qubit cluster state across their logical subsystems, which lies at the heart of their utility for measurement-based quantum computing. To complement the analytical approach, we introduce a simple graphical description of these CV-mode cluster states that depicts precisely how the hidden qubit cluster states are entangled with the gauge modes, and we outline how these results would extend to the case of finitely squeezed states. This work provides important insight that is both conceptually satisfying and helps to address important practical issues like when a simpler resource (such as a Gaussian state) can stand in for a more complex one (like a GKP state), leading to more efficient use of the resources available for CV quantum computing.\n
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\n \n\n \n \n \n \n \n \n Exact holographic tensor networks for the Motzkin spin chain.\n \n \n \n \n\n\n \n Alexander, R. N.; Evenbly, G.; and Klich, I.\n\n\n \n\n\n\n Quantum, 5: 546. September 2021.\n \n\n\n\n
\n\n\n\n \n \n \"ExactPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{Alexander2021exactholographic,\n\tabstract = {The study of low-dimensional quantum systems has proven to be a particularly fertile field for discovering novel types of quantum matter. When studied numerically, low-energy states of low-dimensional quantum systems are often approximated via a tensor-network description. The tensor network's utility in studying short range correlated states in 1D have been thoroughly investigated, with numerous examples where the treatment is essentially exact. Yet, despite the large number of works investigating these networks and their relations to physical models, examples of exact correspondence between the ground state of a quantum critical system and an appropriate scale-invariant tensor network have eluded us so far. Here we show that the features of the quantum-critical Motzkin model can be faithfully captured by an analytic tensor network that exactly represents the ground state of the physical Hamiltonian. In particular, our network offers a two-dimensional representation of this state by a correspondence between walks and a type of tiling of a square lattice. We discuss connections to renormalization and holography.},\n\tauthor = {Alexander, Rafael N. and Evenbly, Glen and Klich, Israel},\n\tdate-added = {2021-09-23 14:28:50 +1000},\n\tdate-modified = {2021-09-23 14:29:34 +1000},\n\tdoi = {10.22331/q-2021-09-21-546},\n\tissn = {2521-327X},\n\tjournal = {{Quantum}},\n\tmonth = sep,\n\tpages = {546},\n\tpublisher = {{Verein zur F{\\"{o}}rderung des Open Access Publizierens in den Quantenwissenschaften}},\n\ttitle = {Exact holographic tensor networks for the {M}otzkin spin chain},\n\turl = {https://doi.org/10.22331/q-2021-09-21-546},\n\tvolume = {5},\n\tyear = {2021},\n\tBdsk-Url-1 = {https://doi.org/10.22331/q-2021-09-21-546}}\n\n
\n
\n\n\n
\n The study of low-dimensional quantum systems has proven to be a particularly fertile field for discovering novel types of quantum matter. When studied numerically, low-energy states of low-dimensional quantum systems are often approximated via a tensor-network description. The tensor network's utility in studying short range correlated states in 1D have been thoroughly investigated, with numerous examples where the treatment is essentially exact. Yet, despite the large number of works investigating these networks and their relations to physical models, examples of exact correspondence between the ground state of a quantum critical system and an appropriate scale-invariant tensor network have eluded us so far. Here we show that the features of the quantum-critical Motzkin model can be faithfully captured by an analytic tensor network that exactly represents the ground state of the physical Hamiltonian. In particular, our network offers a two-dimensional representation of this state by a correspondence between walks and a type of tiling of a square lattice. We discuss connections to renormalization and holography.\n
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\n \n\n \n \n \n \n \n \n Particle scattering in a sonic analogue of special relativity.\n \n \n \n \n\n\n \n Todd, S. L.; Pantaleoni, G.; Baccetti, V.; and Menicucci, N. C.\n\n\n \n\n\n\n Phys. Rev. D, 104: 064035. Sep 2021.\n \n\n\n\n
\n\n\n\n \n \n \"ParticlePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{Todd2021,\n\tabstract = {We investigate a simple toy model of particle scattering in the flat spacetime limit of an analogue-gravity model. The analogue-gravity medium is treated as a scalar field of phonons that obeys the Klein--Gordon equation and thus admits a Lorentz symmetry with respect to $c_s$, the speed of sound in the medium. The particle from which the phonons are scattered is external to the system and does not obey the sonic Lorentz symmetry that the phonon field obeys. In-universe observers who use the exchange of sound to operationally measure distance and duration find that the external particle appears to be a sonically Lorentz-violating particle. By performing a sonic analogue to Compton scattering, in-universe observers can determine if they are in motion with respect to their medium. If in-universe observers were then to correctly postulate the dispersion relation of the external particle, their velocity with respect to the medium could be found.},\n\tauthor = {Todd, Scott L. and Pantaleoni, Giacomo and Baccetti, Valentina and Menicucci, Nicolas C.},\n\tdate-added = {2021-09-16 14:41:25 +1000},\n\tdate-modified = {2021-09-16 14:42:03 +1000},\n\tdoi = {10.1103/PhysRevD.104.064035},\n\tissue = {6},\n\tjournal = {Phys. Rev. D},\n\tmonth = {Sep},\n\tnumpages = {23},\n\tpages = {064035},\n\tpublisher = {American Physical Society},\n\ttitle = {Particle scattering in a sonic analogue of special relativity},\n\turl = {https://link.aps.org/doi/10.1103/PhysRevD.104.064035},\n\tvolume = {104},\n\tyear = {2021},\n\tBdsk-Url-1 = {https://link.aps.org/doi/10.1103/PhysRevD.104.064035},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevD.104.064035}}\n\n
\n
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\n We investigate a simple toy model of particle scattering in the flat spacetime limit of an analogue-gravity model. The analogue-gravity medium is treated as a scalar field of phonons that obeys the Klein–Gordon equation and thus admits a Lorentz symmetry with respect to $c_s$, the speed of sound in the medium. The particle from which the phonons are scattered is external to the system and does not obey the sonic Lorentz symmetry that the phonon field obeys. In-universe observers who use the exchange of sound to operationally measure distance and duration find that the external particle appears to be a sonically Lorentz-violating particle. By performing a sonic analogue to Compton scattering, in-universe observers can determine if they are in motion with respect to their medium. If in-universe observers were then to correctly postulate the dispersion relation of the external particle, their velocity with respect to the medium could be found.\n
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\n \n\n \n \n \n \n \n \n Subsystem analysis of continuous-variable resource states.\n \n \n \n \n\n\n \n Pantaleoni, G.; Baragiola, B. Q.; and Menicucci, N. C.\n\n\n \n\n\n\n Phys. Rev. A, 104: 012430. Jul 2021.\n \n\n\n\n
\n\n\n\n \n \n \"SubsystemPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{PhysRevA.104.012430,\n\tabstract = {Continuous-variable (CV) cluster states are a universal resource for fault-tolerant quantum computation when supplemented with the Gottesman-Kitaev-Preskill (GKP) bosonic code. We generalize the recently introduced subsystem decomposition of a bosonic mode [G. Pantaleoni et al., Phys. Rev. Lett. 125, 040501 (2020)], and we use it to analyze CV cluster-state quantum computing with GKP states. Specifically, we decompose squeezed-vacuum states and approximate GKP states to reveal their encoded logical information, and we decompose several gates crucial to CV cluster-state quantum computing. Then, we use the subsystem decomposition to quantify damage to the logical information in approximate GKP states teleported through noisy CV cluster states. Each of these studies uses the subsystem decomposition to circumvent complications arising from the full CV nature of the mode in order to focus on the encoded qubit information.},\n\tauthor = {Pantaleoni, Giacomo and Baragiola, Ben Q. and Menicucci, Nicolas C.},\n\tdate-added = {2021-08-27 16:21:36 +1000},\n\tdate-modified = {2021-08-27 16:21:48 +1000},\n\tdoi = {10.1103/PhysRevA.104.012430},\n\tissue = {1},\n\tjournal = {Phys. Rev. A},\n\tmonth = {Jul},\n\tnumpages = {20},\n\tpages = {012430},\n\tpublisher = {American Physical Society},\n\ttitle = {Subsystem analysis of continuous-variable resource states},\n\turl = {https://link.aps.org/doi/10.1103/PhysRevA.104.012430},\n\tvolume = {104},\n\tyear = {2021},\n\tBdsk-Url-1 = {https://link.aps.org/doi/10.1103/PhysRevA.104.012430},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.104.012430}}\n\n
\n
\n\n\n
\n Continuous-variable (CV) cluster states are a universal resource for fault-tolerant quantum computation when supplemented with the Gottesman-Kitaev-Preskill (GKP) bosonic code. We generalize the recently introduced subsystem decomposition of a bosonic mode [G. Pantaleoni et al., Phys. Rev. Lett. 125, 040501 (2020)], and we use it to analyze CV cluster-state quantum computing with GKP states. Specifically, we decompose squeezed-vacuum states and approximate GKP states to reveal their encoded logical information, and we decompose several gates crucial to CV cluster-state quantum computing. Then, we use the subsystem decomposition to quantify damage to the logical information in approximate GKP states teleported through noisy CV cluster states. Each of these studies uses the subsystem decomposition to circumvent complications arising from the full CV nature of the mode in order to focus on the encoded qubit information.\n
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\n \n\n \n \n \n \n \n \n Entanglement harvesting with coherently delocalized matter.\n \n \n \n \n\n\n \n Stritzelberger, N.; Henderson, L. J.; Baccetti, V.; Menicucci, N. C.; and Kempf, A.\n\n\n \n\n\n\n Phys. Rev. D, 103. Jan 2021.\n \n\n\n\n
\n\n\n\n \n \n \"EntanglementPaper\n  \n \n \n \"Entanglement link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{PhysRevD.103.016007,\n\tabstract = {We study entanglement harvesting for matter systems such as atoms, ions or molecules whose center of mass degrees of freedom are quantum delocalized and which couple to a relativistic quantum field. We employ a generalized Unruh-deWitt detector model for the light-matter interaction, and we investigate how the coherent spreading of the quantum center of mass wave function of two delocalized detector systems impacts their ability to become entangled with one another, via their respective interaction with a quantum field. For very massive detectors with initially highly localized centers of mass, we recover the results of entanglement harvesting for pointlike Unruh-deWitt detectors with classical center of mass degrees of freedom. We find that entanglement harvesting is Gaussian suppressed in the initial center of mass delocalization of the detectors. We further find that spatial smearing profiles, which are commonly employed to model the finite size of atoms due to their atomic orbitals, are not suited to model center of mass delocalization. Finally, for coherently delocalized detectors, we compare entanglement harvesting in the vacuum to entanglement harvesting in media. We find that entanglement harvesting is significantly suppressed in media in which the wave propagation speed is much smaller than the vacuum speed of light.},\n\tart_number = {016007},\n\tauthor = {Stritzelberger, Nadine and Henderson, Laura J. and Baccetti, Valentina and Menicucci, Nicolas C. and Kempf, Achim},\n\tdate-added = {2021-02-05 09:38:44 +1100},\n\tdate-modified = {2021-02-05 09:40:55 +1100},\n\tdoi = {10.1103/PhysRevD.103.016007},\n\tissue = {1},\n\tjournal = {Phys. Rev. D},\n\tmonth = {Jan},\n\tnumpages = {14},\n\tpublisher = {American Physical Society},\n\ttitle = {Entanglement harvesting with coherently delocalized matter},\n\turl = {https://link.aps.org/doi/10.1103/PhysRevD.103.016007},\n\turl_link = {https://link.aps.org/doi/10.1103/PhysRevD.103.016007},\n\tvolume = {103},\n\tyear = {2021},\n\tBdsk-Url-1 = {https://link.aps.org/doi/10.1103/PhysRevD.103.016007},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevD.103.016007}}\n\n
\n
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\n We study entanglement harvesting for matter systems such as atoms, ions or molecules whose center of mass degrees of freedom are quantum delocalized and which couple to a relativistic quantum field. We employ a generalized Unruh-deWitt detector model for the light-matter interaction, and we investigate how the coherent spreading of the quantum center of mass wave function of two delocalized detector systems impacts their ability to become entangled with one another, via their respective interaction with a quantum field. For very massive detectors with initially highly localized centers of mass, we recover the results of entanglement harvesting for pointlike Unruh-deWitt detectors with classical center of mass degrees of freedom. We find that entanglement harvesting is Gaussian suppressed in the initial center of mass delocalization of the detectors. We further find that spatial smearing profiles, which are commonly employed to model the finite size of atoms due to their atomic orbitals, are not suited to model center of mass delocalization. Finally, for coherently delocalized detectors, we compare entanglement harvesting in the vacuum to entanglement harvesting in media. We find that entanglement harvesting is significantly suppressed in media in which the wave propagation speed is much smaller than the vacuum speed of light.\n
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\n  \n 2020\n \n \n (5)\n \n \n
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\n \n\n \n \n \n \n \n \n Continuous-variable gate teleportation and bosonic-code error correction.\n \n \n \n \n\n\n \n Walshe, B. W.; Baragiola, B. Q.; Alexander, R. N.; and Menicucci, N. C.\n\n\n \n\n\n\n Phys. Rev. A, 102. Dec 2020.\n \n\n\n\n
\n\n\n\n \n \n \"Continuous-variablePaper\n  \n \n \n \"Continuous-variable link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{PhysRevA.102.062411,\n\tabstract = {We examine continuous-variable gate teleportation using entangled states made from pure product states sent through a beam splitter. We show that such states are Choi states for a (typically) nonunitary gate, and we derive the associated Kraus operator for teleportation, which can be used to realize non-Gaussian, nonunitary quantum operations on an input state. With this result, we show how gate teleportation is used to perform error correction on bosonic qubits encoded using the Gottesman-Kitaev-Preskill (GKP) code. This result is presented in the context of deterministically produced macronode cluster states, generated by constant-depth linear optical networks, supplemented with a probabilistic supply of GKP states. The upshot of our technique is that state injection for both gate teleportation and error correction can be achieved without active squeezing operations---an experimental bottleneck for quantum optical implementations.},\n\tart_number = {062411},\n\tauthor = {Walshe, Blayney W. and Baragiola, Ben Q. and Alexander, Rafael N. and Menicucci, Nicolas C.},\n\tdate-added = {2021-02-05 09:45:10 +1100},\n\tdate-modified = {2021-02-05 09:45:57 +1100},\n\tdoi = {10.1103/PhysRevA.102.062411},\n\tissue = {6},\n\tjournal = {Phys. Rev. A},\n\tmonth = {Dec},\n\tnumpages = {19},\n\tpublisher = {American Physical Society},\n\ttitle = {Continuous-variable gate teleportation and bosonic-code error correction},\n\turl = {https://link.aps.org/doi/10.1103/PhysRevA.102.062411},\n\turl_link = {https://link.aps.org/doi/10.1103/PhysRevA.102.062411},\n\tvolume = {102},\n\tyear = {2020},\n\tBdsk-Url-1 = {https://link.aps.org/doi/10.1103/PhysRevA.102.062411},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.102.062411}}\n\n
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\n We examine continuous-variable gate teleportation using entangled states made from pure product states sent through a beam splitter. We show that such states are Choi states for a (typically) nonunitary gate, and we derive the associated Kraus operator for teleportation, which can be used to realize non-Gaussian, nonunitary quantum operations on an input state. With this result, we show how gate teleportation is used to perform error correction on bosonic qubits encoded using the Gottesman-Kitaev-Preskill (GKP) code. This result is presented in the context of deterministically produced macronode cluster states, generated by constant-depth linear optical networks, supplemented with a probabilistic supply of GKP states. The upshot of our technique is that state injection for both gate teleportation and error correction can be achieved without active squeezing operations—an experimental bottleneck for quantum optical implementations.\n
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\n \n\n \n \n \n \n \n \n Bandlimited entanglement harvesting.\n \n \n \n \n\n\n \n Henderson, L. J.; and Menicucci, N. C.\n\n\n \n\n\n\n Phys. Rev. D, 102. Dec 2020.\n \n\n\n\n
\n\n\n\n \n \n \"BandlimitedPaper\n  \n \n \n \"Bandlimited link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{PhysRevD.102.125026,\n\tabstract = {There are many reasons to believe that there is a fundamental minimum length scale below which distances cannot be reliably resolved. One method of constructing a quantum field with a finite minimum length scale is to use bandlimited quantum field theory, where the spacetime is mathematically both continuous and discrete. This is a modification to the field, which has been shown to have many consequences at the level of the field. We consider an operational approach and use a pair of particle detectors (two-level qubits) as a local probe of the field, which are coupled to the vacuum of the bandlimited massless scalar field in a time-dependent way through a switching function. We show that, mathematically, the bandlimit modifies the spatial profile of the detectors so that they are only quasilocal. We explore two different types of switching functions, Gaussian and Dirac delta. We find that, with Gaussian switching, the bandlimit exponentially suppresses the deexcitation of the detectors when the energy gap between the two levels is larger than the bandlimit. If the detectors are prepared in ground state, in certain regions of the parameter space they are able to extract more entanglement from the field than if there was no bandlimit. When the detectors couple with Dirac-delta switching, we show that a particle detector is most sensitive to the bandlimit when it couples to a small but finite region of spacetime. We find that the effects of a bandlimit are detectable using local probes. This work is important because it illustrates the possible observable consequences of a fundamental bandlimit in a quantum field.},\n\tart_number = {125026},\n\tauthor = {Henderson, Laura J. and Menicucci, Nicolas C.},\n\tdate-added = {2021-02-05 09:43:04 +1100},\n\tdate-modified = {2021-02-05 09:44:09 +1100},\n\tdoi = {10.1103/PhysRevD.102.125026},\n\tissue = {12},\n\tjournal = {Phys. Rev. D},\n\tmonth = {Dec},\n\tnumpages = {13},\n\tpublisher = {American Physical Society},\n\ttitle = {Bandlimited entanglement harvesting},\n\turl = {https://link.aps.org/doi/10.1103/PhysRevD.102.125026},\n\turl_link = {https://link.aps.org/doi/10.1103/PhysRevD.102.125026},\n\tvolume = {102},\n\tyear = {2020},\n\tBdsk-Url-1 = {https://link.aps.org/doi/10.1103/PhysRevD.102.125026},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevD.102.125026}}\n\n
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\n There are many reasons to believe that there is a fundamental minimum length scale below which distances cannot be reliably resolved. One method of constructing a quantum field with a finite minimum length scale is to use bandlimited quantum field theory, where the spacetime is mathematically both continuous and discrete. This is a modification to the field, which has been shown to have many consequences at the level of the field. We consider an operational approach and use a pair of particle detectors (two-level qubits) as a local probe of the field, which are coupled to the vacuum of the bandlimited massless scalar field in a time-dependent way through a switching function. We show that, mathematically, the bandlimit modifies the spatial profile of the detectors so that they are only quasilocal. We explore two different types of switching functions, Gaussian and Dirac delta. We find that, with Gaussian switching, the bandlimit exponentially suppresses the deexcitation of the detectors when the energy gap between the two levels is larger than the bandlimit. If the detectors are prepared in ground state, in certain regions of the parameter space they are able to extract more entanglement from the field than if there was no bandlimit. When the detectors couple with Dirac-delta switching, we show that a particle detector is most sensitive to the bandlimit when it couples to a small but finite region of spacetime. We find that the effects of a bandlimit are detectable using local probes. This work is important because it illustrates the possible observable consequences of a fundamental bandlimit in a quantum field.\n
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\n \n\n \n \n \n \n \n \n Modular Bosonic Subsystem Codes.\n \n \n \n \n\n\n \n Pantaleoni, G.; Baragiola, B. Q.; and Menicucci, N. C.\n\n\n \n\n\n\n Phys. Rev. Lett., 125: 040501. Jul 2020.\n \n\n\n\n
\n\n\n\n \n \n \"Modular link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{PhysRevLett.125.040501,\n\tauthor = {Pantaleoni, Giacomo and Baragiola, Ben Q. and Menicucci, Nicolas C.},\n\tdate-added = {2020-08-27 10:08:51 +1000},\n\tdate-modified = {2020-08-27 10:08:51 +1000},\n\tdoi = {10.1103/PhysRevLett.125.040501},\n\tissue = {4},\n\tjournal = {Phys. Rev. Lett.},\n\tmonth = {Jul},\n\tnumpages = {6},\n\tpages = {040501},\n\tpublisher = {American Physical Society},\n\ttitle = {Modular Bosonic Subsystem Codes},\n\turl_link = {https://link.aps.org/doi/10.1103/PhysRevLett.125.040501},\n\tvolume = {125},\n\tyear = {2020},\n\tBdsk-Url-1 = {https://link.aps.org/doi/10.1103/PhysRevLett.125.040501},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevLett.125.040501}}\n\n
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\n \n\n \n \n \n \n \n \n Quantum Computing with Rotation-Symmetric Bosonic Codes.\n \n \n \n \n\n\n \n Grimsmo, A. L.; Combes, J.; and Baragiola, B. Q.\n\n\n \n\n\n\n Phys. Rev. X, 10. Mar 2020.\n \n\n\n\n
\n\n\n\n \n \n \"Quantum link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{PhysRevX.10.011058,\n\tabstract = {Bosonic rotation codes, introduced here, are a broad class of bosonic error-correcting codes based on phase-space rotation symmetry. We present a universal quantum computing scheme applicable to a subset of this class---number-phase codes---which includes the well-known cat and binomial codes, among many others. The entangling gate in our scheme is code agnostic and can be used to interface different rotation-symmetric encodings. In addition to a universal set of operations, we propose a teleportation-based error-correction scheme that allows recoveries to be tracked entirely in software. Focusing on cat and binomial codes as examples, we compute average gate fidelities for error correction under simultaneous loss and dephasing noise and show numerically that the error-correction scheme is close to optimal for error-free ancillae and ideal measurements. Finally, we present a scheme for fault-tolerant, universal quantum computing based on the concatenation of number-phase codes and Bacon-Shor subsystem codes.},\n\tart_number = {011058},\n\tauthor = {Grimsmo, Arne L. and Combes, Joshua and Baragiola, Ben Q.},\n\tdate-added = {2020-06-26 14:11:54 +1000},\n\tdate-modified = {2020-06-26 14:12:31 +1000},\n\tdoi = {10.1103/PhysRevX.10.011058},\n\tissue = {1},\n\tjournal = {Phys. Rev. X},\n\tmonth = {Mar},\n\tnumpages = {32},\n\tpublisher = {American Physical Society},\n\ttitle = {Quantum Computing with Rotation-Symmetric Bosonic Codes},\n\turl_link = {https://link.aps.org/doi/10.1103/PhysRevX.10.011058},\n\tvolume = {10},\n\tyear = {2020},\n\tBdsk-Url-1 = {https://link.aps.org/doi/10.1103/PhysRevX.10.011058},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevX.10.011058}}\n\n
\n
\n\n\n
\n Bosonic rotation codes, introduced here, are a broad class of bosonic error-correcting codes based on phase-space rotation symmetry. We present a universal quantum computing scheme applicable to a subset of this class—number-phase codes—which includes the well-known cat and binomial codes, among many others. The entangling gate in our scheme is code agnostic and can be used to interface different rotation-symmetric encodings. In addition to a universal set of operations, we propose a teleportation-based error-correction scheme that allows recoveries to be tracked entirely in software. Focusing on cat and binomial codes as examples, we compute average gate fidelities for error correction under simultaneous loss and dephasing noise and show numerically that the error-correction scheme is close to optimal for error-free ancillae and ideal measurements. Finally, we present a scheme for fault-tolerant, universal quantum computing based on the concatenation of number-phase codes and Bacon-Shor subsystem codes.\n
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\n \n\n \n \n \n \n \n \n Progress towards practical qubit computation using approximate Gottesman-Kitaev-Preskill codes.\n \n \n \n \n\n\n \n Tzitrin, I.; Bourassa, J. E.; Menicucci, N. C.; and Sabapathy, K. K.\n\n\n \n\n\n\n Phys. Rev. A, 101. Mar 2020.\n \n\n\n\n
\n\n\n\n \n \n \"Progress link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{PhysRevA.101.032315,\n\tabstract = {Encoding a qubit in the continuous degrees of freedom of an oscillator is a promising path to error-corrected quantum computation. One advantageous way to achieve this is through Gottesman-Kitaev-Preskill (GKP) grid states, whose symmetries allow for the correction of any small continuous error on the oscillator. Unfortunately, ideal grid states have infinite energy, so it is important to find finite-energy approximations that are realistic, practical, and useful for applications. In the first half of this work we investigate the impact of imperfect GKP states on computational circuits independently of the physical architecture. To this end, we analyze the behavior of the physical and logical content of normalizable GKP states through several figures of merit, employing a recently developed modular subsystem decomposition. By tracking the errors that enter into the computational circuit due to imperfections in the GKP states, we are able to gauge the utility of these states for noisy intermediate-scale quantum devices. In the second half, we focus on a state preparation approach in the photonic domain wherein photon-number-resolving measurements on some modes of Gaussian states produce non-Gaussian states in others. We produce detailed numerical results for the preparation of GKP states alongside estimating the resource requirements in practical settings and probing the quality of the resulting states with the tools we develop. Our numerical experiments indicate that we can generate any state in the GKP Bloch sphere with nearly equal resources, which has implications for magic state preparation overheads.},\n\tart_number = {032315},\n\tauthor = {Tzitrin, Ilan and Bourassa, J. Eli and Menicucci, Nicolas C. and Sabapathy, Krishna Kumar},\n\tdate-added = {2020-06-26 14:09:20 +1000},\n\tdate-modified = {2020-06-26 14:13:10 +1000},\n\tdoi = {10.1103/PhysRevA.101.032315},\n\tissue = {3},\n\tjournal = {Phys. Rev. A},\n\tmonth = {Mar},\n\tnumpages = {31},\n\tpublisher = {American Physical Society},\n\ttitle = {Progress towards practical qubit computation using approximate Gottesman-Kitaev-Preskill codes},\n\turl_link = {https://link.aps.org/doi/10.1103/PhysRevA.101.032315},\n\tvolume = {101},\n\tyear = {2020},\n\tBdsk-Url-1 = {https://link.aps.org/doi/10.1103/PhysRevA.101.032315},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.101.032315}}\n\n
\n
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\n Encoding a qubit in the continuous degrees of freedom of an oscillator is a promising path to error-corrected quantum computation. One advantageous way to achieve this is through Gottesman-Kitaev-Preskill (GKP) grid states, whose symmetries allow for the correction of any small continuous error on the oscillator. Unfortunately, ideal grid states have infinite energy, so it is important to find finite-energy approximations that are realistic, practical, and useful for applications. In the first half of this work we investigate the impact of imperfect GKP states on computational circuits independently of the physical architecture. To this end, we analyze the behavior of the physical and logical content of normalizable GKP states through several figures of merit, employing a recently developed modular subsystem decomposition. By tracking the errors that enter into the computational circuit due to imperfections in the GKP states, we are able to gauge the utility of these states for noisy intermediate-scale quantum devices. In the second half, we focus on a state preparation approach in the photonic domain wherein photon-number-resolving measurements on some modes of Gaussian states produce non-Gaussian states in others. We produce detailed numerical results for the preparation of GKP states alongside estimating the resource requirements in practical settings and probing the quality of the resulting states with the tools we develop. Our numerical experiments indicate that we can generate any state in the GKP Bloch sphere with nearly equal resources, which has implications for magic state preparation overheads.\n
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\n  \n 2019\n \n \n (6)\n \n \n
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\n \n\n \n \n \n \n \n \n Power and efficiency of a thermal engine with a coherent bath.\n \n \n \n \n\n\n \n Guff, T.; Daryanoosh, S.; Baragiola, B. Q.; and Gilchrist, A.\n\n\n \n\n\n\n Phys. Rev. E, 100: 032129. Sep 2019.\n \n\n\n\n
\n\n\n\n \n \n \"Power link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{Guff2019,\n\tabstract = {We consider a quantum engine driven by repeated weak interaction with a heat bath of identical three-level atoms. This model was first introduced by Scully et al. [Science, 2003], who showed that coherence between the energy-degenerate ground states serves as a thermodynamic resource that allows operation of a thermal cycle with a coherence-dependent thermalisation temperature. We consider a similar engine out of the quasistatic limit and find that the ground-state coherence also determines the rate of thermalisation, therefore increasing the output power and the engine efficiency only when the thermalisation temperature is reduced. This allows us to optimise the output power by adjusting the coherence and relative stroke durations.},\n\tart_number = {032129},\n\tauthor = {Guff, Thomas and Daryanoosh, Shakib and Baragiola, Ben Q. and Gilchrist, Alexei},\n\tdate-added = {2020-07-02 09:33:33 +1000},\n\tdate-modified = {2020-07-02 09:34:54 +1000},\n\tdoi = {10.1103/PhysRevE.100.032129},\n\tissue = {3},\n\tjournal = {Phys. Rev. E},\n\tmonth = {Sep},\n\tnumpages = {12},\n\tpages = {032129},\n\tpublisher = {American Physical Society},\n\ttitle = {Power and efficiency of a thermal engine with a coherent bath},\n\turl_link = {https://link.aps.org/doi/10.1103/PhysRevE.100.032129},\n\tvolume = {100},\n\tyear = {2019},\n\tBdsk-Url-1 = {https://link.aps.org/doi/10.1103/PhysRevE.100.032129},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevE.100.032129}}\n\n
\n
\n\n\n
\n We consider a quantum engine driven by repeated weak interaction with a heat bath of identical three-level atoms. This model was first introduced by Scully et al. [Science, 2003], who showed that coherence between the energy-degenerate ground states serves as a thermodynamic resource that allows operation of a thermal cycle with a coherence-dependent thermalisation temperature. We consider a similar engine out of the quasistatic limit and find that the ground-state coherence also determines the rate of thermalisation, therefore increasing the output power and the engine efficiency only when the thermalisation temperature is reduced. This allows us to optimise the output power by adjusting the coherence and relative stroke durations.\n
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\n \n\n \n \n \n \n \n \n All-Gaussian Universality and Fault Tolerance with the Gottesman-Kitaev-Preskill Code.\n \n \n \n \n\n\n \n Baragiola, B. Q.; Pantaleoni, G.; Alexander, R. N.; Karanjai, A.; and Menicucci, N. C.\n\n\n \n\n\n\n Phys. Rev. Lett., 123: 200502. Nov 2019.\n \n\n\n\n
\n\n\n\n \n \n \"All-Gaussian link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{PhysRevLett.123.200502,\n\tabstract = {The Gottesman-Kitaev-Preskill (GKP) encoding of a qubit within an oscillator is particularly appealing for fault-tolerant quantum computing with bosons because Gaussian operations on encoded Pauli eigenstates enable Clifford quantum computing with error correction. We show that applying GKP error correction to Gaussian input states, such as vacuum, produces distillable magic states, achieving universality without additional non-Gaussian elements. Fault tolerance is possible with sufficient squeezing and low enough external noise. Thus, Gaussian operations are sufficient for fault-tolerant, universal quantum computing given a supply of GKP-encoded Pauli eigenstates.},\n\tauthor = {Baragiola, Ben Q. and Pantaleoni, Giacomo and Alexander, Rafael N. and Karanjai, Angela and Menicucci, Nicolas C.},\n\tdate-added = {2020-06-26 14:16:59 +1000},\n\tdate-modified = {2020-06-26 14:17:28 +1000},\n\tdoi = {10.1103/PhysRevLett.123.200502},\n\tissue = {20},\n\tjournal = {Phys. Rev. Lett.},\n\tmonth = {Nov},\n\tnumpages = {6},\n\tpages = {200502},\n\tpublisher = {American Physical Society},\n\ttitle = {All-Gaussian Universality and Fault Tolerance with the Gottesman-Kitaev-Preskill Code},\n\turl_link = {https://link.aps.org/doi/10.1103/PhysRevLett.123.200502},\n\tvolume = {123},\n\tyear = {2019},\n\tBdsk-Url-1 = {https://link.aps.org/doi/10.1103/PhysRevLett.123.200502},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevLett.123.200502}}\n\n
\n
\n\n\n
\n The Gottesman-Kitaev-Preskill (GKP) encoding of a qubit within an oscillator is particularly appealing for fault-tolerant quantum computing with bosons because Gaussian operations on encoded Pauli eigenstates enable Clifford quantum computing with error correction. We show that applying GKP error correction to Gaussian input states, such as vacuum, produces distillable magic states, achieving universality without additional non-Gaussian elements. Fault tolerance is possible with sufficient squeezing and low enough external noise. Thus, Gaussian operations are sufficient for fault-tolerant, universal quantum computing given a supply of GKP-encoded Pauli eigenstates.\n
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\n \n\n \n \n \n \n \n \n Black hole evaporation and semiclassical thin shell collapse.\n \n \n \n \n\n\n \n Baccetti, V.; Murk, S.; and Terno, D. R.\n\n\n \n\n\n\n Phys. Rev. D, 100: 064054. Sep 2019.\n \n\n\n\n
\n\n\n\n \n \n \"Black link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Baccetti2019,\n\tabstract = {In case of spherical symmetry, the assumptions of finite-time formation of a trapped region and regularity of its boundary---the apparent horizon---are sufficient to identify the form of the metric and energy-momentum tensor in its vicinity. By comparison with the known results for quasistatic evaporation of black holes, we complete the identification of their parameters. Consistency of the Einstein equations allows only two possible types of higher-order terms in the energy-momentum tensor. By using its local conservation, we provide a method of calculation of the higher-order terms, explicitly determining the leading-order regular corrections. Contraction of a spherically symmetric thin dust shell is the simplest model of gravitational collapse. Nevertheless, the inclusion of a collapse-triggered radiation in different extensions of this model leads to apparent contradictions. Using our results, we resolve these contradictions and show how gravitational collapse may be completed in finite time according to a distant observer.},\n\tart_number = {064054},\n\tauthor = {Baccetti, Valentina and Murk, Sebastian and Terno, Daniel R.},\n\tdate-added = {2019-11-04 16:22:13 +1100},\n\tdate-modified = {2019-11-04 16:23:14 +1100},\n\tdoi = {10.1103/PhysRevD.100.064054},\n\tissue = {6},\n\tjournal = {Phys. Rev. D},\n\tmonth = {Sep},\n\tnumpages = {11},\n\tpages = {064054},\n\tpublisher = {American Physical Society},\n\ttitle = {Black hole evaporation and semiclassical thin shell collapse},\n\turl_link = {https://link.aps.org/doi/10.1103/PhysRevD.100.064054},\n\tvolume = {100},\n\tyear = {2019},\n\tBdsk-Url-1 = {https://link.aps.org/doi/10.1103/PhysRevD.100.064054},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevD.100.064054}}\n\n
\n
\n\n\n
\n In case of spherical symmetry, the assumptions of finite-time formation of a trapped region and regularity of its boundary—the apparent horizon—are sufficient to identify the form of the metric and energy-momentum tensor in its vicinity. By comparison with the known results for quasistatic evaporation of black holes, we complete the identification of their parameters. Consistency of the Einstein equations allows only two possible types of higher-order terms in the energy-momentum tensor. By using its local conservation, we provide a method of calculation of the higher-order terms, explicitly determining the leading-order regular corrections. Contraction of a spherically symmetric thin dust shell is the simplest model of gravitational collapse. Nevertheless, the inclusion of a collapse-triggered radiation in different extensions of this model leads to apparent contradictions. Using our results, we resolve these contradictions and show how gravitational collapse may be completed in finite time according to a distant observer.\n
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\n \n\n \n \n \n \n \n \n Generation of time-domain-multiplexed two-dimensional cluster state.\n \n \n \n \n\n\n \n Asavanant, W.; Shiozawa, Y.; Yokoyama, S.; Charoensombutamon, B.; Emura, H.; Alexander, R. N.; Takeda, S.; Yoshikawa, J.; Menicucci, N. C.; Yonezawa, H.; and Furusawa, A.\n\n\n \n\n\n\n Science, 366(6463): 373–376. 2019.\n \n\n\n\n
\n\n\n\n \n \n \"Generation link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Asavanant373,\n\tabstract = {Entanglement is the key resource for measurement-based quantum computing. It is stored in quantum states known as cluster states, which are prepared offline and enable quantum computing by means of purely local measurements. Universal quantum computing requires cluster states that are both large and possess (at least) a two-dimensional topology. Continuous-variable cluster states{\\textemdash}based on bosonic modes rather than qubits{\\textemdash}have previously been generated on a scale exceeding one million modes, but only in one dimension. Here, we report generation of a large-scale two-dimensional continuous-variable cluster state. Its structure consists of a 5- by 1240-site square lattice that was tailored to our highly scalable time-multiplexed experimental platform. It is compatible with Bosonic error-correcting codes that, with higher squeezing, enable fault-tolerant quantum computation.},\n\tart_number = {2645},\n\tauthor = {Asavanant, Warit and Shiozawa, Yu and Yokoyama, Shota and Charoensombutamon, Baramee and Emura, Hiroki and Alexander, Rafael N. and Takeda, Shuntaro and Yoshikawa, Jun-ichi and Menicucci, Nicolas C. and Yonezawa, Hidehiro and Furusawa, Akira},\n\tdate-added = {2019-11-04 16:15:48 +1100},\n\tdate-modified = {2019-11-04 16:21:42 +1100},\n\tdoi = {10.1126/science.aay2645},\n\teprint = {https://science.sciencemag.org/content/366/6463/373.full.pdf},\n\tissn = {0036-8075},\n\tjournal = {Science},\n\tnumber = {6463},\n\tpages = {373--376},\n\tpublisher = {American Association for the Advancement of Science},\n\ttitle = {Generation of time-domain-multiplexed two-dimensional cluster state},\n\turl_link = {https://science.sciencemag.org/content/366/6463/373},\n\tvolume = {366},\n\tyear = {2019},\n\tBdsk-Url-1 = {https://science.sciencemag.org/content/366/6463/373},\n\tBdsk-Url-2 = {https://doi.org/10.1126/science.aay2645}}\n\n
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\n Entanglement is the key resource for measurement-based quantum computing. It is stored in quantum states known as cluster states, which are prepared offline and enable quantum computing by means of purely local measurements. Universal quantum computing requires cluster states that are both large and possess (at least) a two-dimensional topology. Continuous-variable cluster states—based on bosonic modes rather than qubits—have previously been generated on a scale exceeding one million modes, but only in one dimension. Here, we report generation of a large-scale two-dimensional continuous-variable cluster state. Its structure consists of a 5- by 1240-site square lattice that was tailored to our highly scalable time-multiplexed experimental platform. It is compatible with Bosonic error-correcting codes that, with higher squeezing, enable fault-tolerant quantum computation.\n
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\n \n\n \n \n \n \n \n \n Robust fault tolerance for continuous-variable cluster states with excess antisqueezing.\n \n \n \n \n\n\n \n Walshe, B. W.; Mensen, L. J.; Baragiola, B. Q.; and Menicucci, N. C.\n\n\n \n\n\n\n Phys. Rev. A, 100. Jul 2019.\n \n\n\n\n
\n\n\n\n \n \n \"Robust link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Walshe2019,\n\tabstract = {The immense scalability of continuous-variable cluster states motivates their study as a platform for quantum computing, with fault tolerance possible given sufficient squeezing and appropriately encoded qubits [N. C. Menicucci, Phys. Rev. Lett. 112, 120504 (2014)]. Here, we expand the scope of that result by showing that additional antisqueezing has no effect on the fault-tolerance threshold, removing the purity requirement for experimental continuous-variable cluster-state quantum computing. We emphasize that the appropriate experimental target for fault-tolerant applications is to directly measure 15--17 dB of squeezing in the cluster state rather than the more conservative upper bound of 20.5 dB.},\n\tart_number = {010301},\n\tauthor = {Walshe, Blayney W. and Mensen, Lucas J. and Baragiola, Ben Q. and Menicucci, Nicolas C.},\n\tdate-added = {2019-07-24 12:25:23 +1000},\n\tdate-modified = {2019-07-24 12:26:56 +1000},\n\tdoi = {10.1103/PhysRevA.100.010301},\n\tissue = {1},\n\tjournal = {Phys. Rev. A},\n\tmonth = {Jul},\n\tnumpages = {5},\n\tpublisher = {American Physical Society},\n\ttitle = {Robust fault tolerance for continuous-variable cluster states with excess antisqueezing},\n\turl_link = {https://link.aps.org/doi/10.1103/PhysRevA.100.010301},\n\tvolume = {100},\n\tyear = {2019},\n\tBdsk-Url-1 = {https://link.aps.org/doi/10.1103/PhysRevA.100.010301},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.100.010301}}\n\n
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\n The immense scalability of continuous-variable cluster states motivates their study as a platform for quantum computing, with fault tolerance possible given sufficient squeezing and appropriately encoded qubits [N. C. Menicucci, Phys. Rev. Lett. 112, 120504 (2014)]. Here, we expand the scope of that result by showing that additional antisqueezing has no effect on the fault-tolerance threshold, removing the purity requirement for experimental continuous-variable cluster-state quantum computing. We emphasize that the appropriate experimental target for fault-tolerant applications is to directly measure 15–17 dB of squeezing in the cluster state rather than the more conservative upper bound of 20.5 dB.\n
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\n \n\n \n \n \n \n \n \n Energy-momentum tensor and metric near the Schwarzschild sphere.\n \n \n \n \n\n\n \n Baccetti, V.; Mann, R. B.; Murk, S.; and Terno, D. R.\n\n\n \n\n\n\n Phys. Rev. D, 99: 124014. Jun 2019.\n \n\n\n\n
\n\n\n\n \n \n \"Energy-momentum link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Baccetti2019,\n\tabstract = {Regularity of the horizon radius r<sub>g</sub> of a collapsing body constrains a limiting form of a spherically symmetric energy-momentum tensor near it. Its nonzero limit belongs to one of four classes that are distinguished only by two signs. As a result, close to r<sub>g</sub> the geometry can always be described by either an ingoing or outgoing Vaidya metric with increasing or decreasing mass. If according to a distant outside observer the trapped regions form in finite time, then the Einstein equations imply violation of the null energy condition. In this case the horizon radius and its rate of change determine the metric in its vicinity, and the hypersurface r=r<sub>g</sub>(t) is timelike during both the expansion and contraction of the trapped region. We present the implications of these results for the firewall paradox and discuss arguments that the required violation of the null energy condition is incompatible with the standard analysis of black hole evaporation.},\n\tart_number = {124014},\n\tauthor = {Baccetti, Valentina and Mann, Robert B. and Murk, Sebastian and Terno, Daniel R.},\n\tdate-added = {2019-07-12 12:56:35 +1000},\n\tdate-modified = {2019-07-12 13:08:10 +1000},\n\tdoi = {10.1103/PhysRevD.99.124014},\n\tissue = {12},\n\tjournal = {Phys. Rev. D},\n\tmonth = {Jun},\n\tnumpages = {11},\n\tpages = {124014},\n\tpublisher = {American Physical Society},\n\ttitle = {Energy-momentum tensor and metric near the Schwarzschild sphere},\n\turl_link = {https://link.aps.org/doi/10.1103/PhysRevD.99.124014},\n\tvolume = {99},\n\tyear = {2019},\n\tBdsk-Url-1 = {https://link.aps.org/doi/10.1103/PhysRevD.99.124014},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevD.99.124014}}\n\n
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\n Regularity of the horizon radius rg of a collapsing body constrains a limiting form of a spherically symmetric energy-momentum tensor near it. Its nonzero limit belongs to one of four classes that are distinguished only by two signs. As a result, close to rg the geometry can always be described by either an ingoing or outgoing Vaidya metric with increasing or decreasing mass. If according to a distant outside observer the trapped regions form in finite time, then the Einstein equations imply violation of the null energy condition. In this case the horizon radius and its rate of change determine the metric in its vicinity, and the hypersurface r=rg(t) is timelike during both the expansion and contraction of the trapped region. We present the implications of these results for the firewall paradox and discuss arguments that the required violation of the null energy condition is incompatible with the standard analysis of black hole evaporation.\n
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\n  \n 2018\n \n \n (5)\n \n \n
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\n \n\n \n \n \n \n \n \n Universal quantum computation with temporal-mode bilayer square lattices.\n \n \n \n \n\n\n \n Alexander, R.; Yokoyama, S.; Furusawa, A.; and Menicucci, N.\n\n\n \n\n\n\n Physical Review A, 97(3). 2018.\n \n\n\n\n
\n\n\n\n \n \n \"Universal link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Alexander2018,\n\tabstract = {We propose an experimental design for universal continuous-variable quantum computation that incorporates recent innovations in linear-optics-based continuous-variable cluster state generation and cubic-phase gate teleportation. The first ingredient is a protocol for generating the bilayer-square-lattice cluster state (a universal resource state) with temporal modes of light. With this state, measurement-based implementation of Gaussian unitary gates requires only homodyne detection. Second, we describe a measurement device that implements an adaptive cubic-phase gate, up to a random phase-space displacement. It requires a two-step sequence of homodyne measurements and consumes a (non-Gaussian) cubic-phase state. {\\copyright} 2018 American Physical Society.},\n\tart_number = {032302},\n\tauthor = {Alexander, R.N. and Yokoyama, S. and Furusawa, A. and Menicucci, N.C.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1103/PhysRevA.97.032302},\n\tjournal = {Physical Review A},\n\tnumber = {3},\n\ttitle = {Universal quantum computation with temporal-mode bilayer square lattices},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044003552&doi=10.1103%2fPhysRevA.97.032302&partnerID=40&md5=5ce844fbc23b9a811b39ce7f31235e2e},\n\tvolume = {97},\n\tyear = {2018},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044003552&doi=10.1103%2fPhysRevA.97.032302&partnerID=40&md5=5ce844fbc23b9a811b39ce7f31235e2e},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.97.032302}}\n\n
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\n We propose an experimental design for universal continuous-variable quantum computation that incorporates recent innovations in linear-optics-based continuous-variable cluster state generation and cubic-phase gate teleportation. The first ingredient is a protocol for generating the bilayer-square-lattice cluster state (a universal resource state) with temporal modes of light. With this state, measurement-based implementation of Gaussian unitary gates requires only homodyne detection. Second, we describe a measurement device that implements an adaptive cubic-phase gate, up to a random phase-space displacement. It requires a two-step sequence of homodyne measurements and consumes a (non-Gaussian) cubic-phase state. © 2018 American Physical Society.\n
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\n \n\n \n \n \n \n \n \n Role of evaporation in gravitational collapse.\n \n \n \n \n\n\n \n Baccetti, V.; Mann, R.; and Terno, D.\n\n\n \n\n\n\n Classical and Quantum Gravity, 35(18). 2018.\n \n\n\n\n
\n\n\n\n \n \n \"Role link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Baccetti2018,\n\tabstract = {We investigate the consequences of the collapse-induced radiation anticipated before formation of the event horizon. After reviewing the principles underlying semi-classical analysis of black holes we illustrate them by modelling collapse of evaporating massive thin dust shells using two families of metrics for the exterior geometry: the outgoing Vaidya metric and the retarded Schwarzschild metric. We describe how hypothetical pre-Hawking radiation modifies the equation of motion for the shell. Provided that a non-zero radiation flux is perceived by a distant observer, the shell never gets closer than a certain sub-Planckian distance from the Schwarzschild radius. This distance depends only on the shell\\'s mass and evaporation rate. The stress-energy tensor is everywhere finite, but a comoving observer encounters firewall-like energy density and flux. We emphasize the logical connections between different assumptions within the semi-classical approach and discuss consequences of the apparent contradictions between them. {\\copyright} 2018 IOP Publishing Ltd.},\n\tart_number = {185005},\n\tauthor = {Baccetti, V. and Mann, R.B. and Terno, D.R.},\n\tdate-added = {2019-03-18 11:59:12 +1100},\n\tdate-modified = {2019-03-18 11:59:12 +1100},\n\tdoi = {10.1088/1361-6382/aad70e},\n\tjournal = {Classical and Quantum Gravity},\n\tnumber = {18},\n\ttitle = {Role of evaporation in gravitational collapse},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053142130&doi=10.1088%2f1361-6382%2faad70e&partnerID=40&md5=9fabc0ebd28d79027ae0c2230434a9a0},\n\tvolume = {35},\n\tyear = {2018},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053142130&doi=10.1088%2f1361-6382%2faad70e&partnerID=40&md5=9fabc0ebd28d79027ae0c2230434a9a0},\n\tBdsk-Url-2 = {https://doi.org/10.1088/1361-6382/aad70e}}\n\n
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\n We investigate the consequences of the collapse-induced radiation anticipated before formation of the event horizon. After reviewing the principles underlying semi-classical analysis of black holes we illustrate them by modelling collapse of evaporating massive thin dust shells using two families of metrics for the exterior geometry: the outgoing Vaidya metric and the retarded Schwarzschild metric. We describe how hypothetical pre-Hawking radiation modifies the equation of motion for the shell. Provided that a non-zero radiation flux is perceived by a distant observer, the shell never gets closer than a certain sub-Planckian distance from the Schwarzschild radius. This distance depends only on the shellś mass and evaporation rate. The stress-energy tensor is everywhere finite, but a comoving observer encounters firewall-like energy density and flux. We emphasize the logical connections between different assumptions within the semi-classical approach and discuss consequences of the apparent contradictions between them. © 2018 IOP Publishing Ltd.\n
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\n \n\n \n \n \n \n \n \n Quantum master equations for entangled qubit environments.\n \n \n \n \n\n\n \n Daryanoosh, S.; Baragiola, B.; Guff, T.; and Gilchrist, A.\n\n\n \n\n\n\n Physical Review A, 98(6). 2018.\n \n\n\n\n
\n\n\n\n \n \n \"Quantum link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Daryanoosh2018,\n\tabstract = {We study the Markovian dynamics of a collection of n quantum systems coupled to an irreversible environmental channel consisting of a stream of entangled qubits. Within the framework of repeated quantum interactions, we derive the master equation for the joint-state dynamics of the n quantum systems. We investigate the evolution of the joint state for two-qubit environments where the presence of antidiagonal coherences in the state of the bath qubits (in the local energy basis) is essential for preserving and generating entanglement between two remote quantum systems. However, maximally entangled bath qubits, such as Bell states, exhibit exceptional behavior, where the master equation does not have a unique steady state and can destroy entanglement between the systems. For the general case of n-qubit environments we show that antidiagonal coherences that arise from multibody entanglement in the bath qubits do not affect the composite system evolution in the weak-coupling regime. {\\copyright} 2018 American Physical Society.},\n\tart_number = {062104},\n\tauthor = {Daryanoosh, S. and Baragiola, B.Q. and Guff, T. and Gilchrist, A.},\n\tdoi = {10.1103/PhysRevA.98.062104},\n\tjournal = {Physical Review A},\n\tnumber = {6},\n\ttitle = {Quantum master equations for entangled qubit environments},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057718003&doi=10.1103%2fPhysRevA.98.062104&partnerID=40&md5=e0e2cdc84efc4a28740a2b95a2193e9c},\n\tvolume = {98},\n\tyear = {2018},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057718003&doi=10.1103%2fPhysRevA.98.062104&partnerID=40&md5=e0e2cdc84efc4a28740a2b95a2193e9c},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.98.062104}}\n\n
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\n We study the Markovian dynamics of a collection of n quantum systems coupled to an irreversible environmental channel consisting of a stream of entangled qubits. Within the framework of repeated quantum interactions, we derive the master equation for the joint-state dynamics of the n quantum systems. We investigate the evolution of the joint state for two-qubit environments where the presence of antidiagonal coherences in the state of the bath qubits (in the local energy basis) is essential for preserving and generating entanglement between two remote quantum systems. However, maximally entangled bath qubits, such as Bell states, exhibit exceptional behavior, where the master equation does not have a unique steady state and can destroy entanglement between the systems. For the general case of n-qubit environments we show that antidiagonal coherences that arise from multibody entanglement in the bath qubits do not affect the composite system evolution in the weak-coupling regime. © 2018 American Physical Society.\n
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\n \n\n \n \n \n \n \n \n Generating nonclassical states of motion using spontaneous emission.\n \n \n \n \n\n\n \n Baragiola, B.; and Twamley, J.\n\n\n \n\n\n\n New Journal of Physics, 20(7). 2018.\n \n\n\n\n
\n\n\n\n \n \n \"Generating link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Baragiola2018,\n\tabstract = {Nonclassical motional states of matter are of interest both from a fundamental perspective but also for their potential technological applications as resources in various quantum processing tasks such as quantum teleportation, sensing, communication, and computation. In this work we explore the motional effects of a harmonically trapped, excited two-level emitter coupled to a one-dimensional photonic system. As the emitter decays it experiences a momentum recoil that entangles its motion with the emitted photon pulse. In the long-time limit the emitter relaxes to its electronic ground state, while its reduced motional state remains entangled with the outgoing photon. We find photonic systems where the long-time reduced motional state of the emitter, though mixed, is highly nonclassical and in some cases approaches a pure motional Fock state. Motional recoil engineering can be simpler to experimentally implement than complex measurement and feedback based methods to engineer novel quantum mechanical states of motion. {\\copyright} 2018 The Author(s). Published by IOP Publishing Ltd on behalf of Deutsche Physikalische Gesellschaft.},\n\tart_number = {073029},\n\tauthor = {Baragiola, B.Q. and Twamley, J.},\n\tdoi = {10.1088/1367-2630/aad1b2},\n\tjournal = {New Journal of Physics},\n\tnumber = {7},\n\ttitle = {Generating nonclassical states of motion using spontaneous emission},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85051141213&doi=10.1088%2f1367-2630%2faad1b2&partnerID=40&md5=90312419ae3d900f6ba9c54c26cc55fd},\n\tvolume = {20},\n\tyear = {2018},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85051141213&doi=10.1088%2f1367-2630%2faad1b2&partnerID=40&md5=90312419ae3d900f6ba9c54c26cc55fd},\n\tBdsk-Url-2 = {https://doi.org/10.1088/1367-2630/aad1b2}}\n\n
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\n Nonclassical motional states of matter are of interest both from a fundamental perspective but also for their potential technological applications as resources in various quantum processing tasks such as quantum teleportation, sensing, communication, and computation. In this work we explore the motional effects of a harmonically trapped, excited two-level emitter coupled to a one-dimensional photonic system. As the emitter decays it experiences a momentum recoil that entangles its motion with the emitted photon pulse. In the long-time limit the emitter relaxes to its electronic ground state, while its reduced motional state remains entangled with the outgoing photon. We find photonic systems where the long-time reduced motional state of the emitter, though mixed, is highly nonclassical and in some cases approaches a pure motional Fock state. Motional recoil engineering can be simpler to experimentally implement than complex measurement and feedback based methods to engineer novel quantum mechanical states of motion. © 2018 The Author(s). Published by IOP Publishing Ltd on behalf of Deutsche Physikalische Gesellschaft.\n
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\n \n\n \n \n \n \n \n \n Anonymous broadcasting of classical information with a continuous-variable topological quantum code.\n \n \n \n \n\n\n \n Menicucci, N.; Baragiola, B.; Demarie, T.; and Brennen, G.\n\n\n \n\n\n\n Physical Review A, 97(3). 2018.\n \n\n\n\n
\n\n\n\n \n \n \"Anonymous link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Menicucci2018,\n\tabstract = {Broadcasting information anonymously becomes more difficult as surveillance technology improves, but remarkably, quantum protocols exist that enable provably traceless broadcasting. The difficulty is making scalable entangled resource states that are robust to errors. We propose an anonymous broadcasting protocol that uses a continuous-variable surface-code state that can be produced using current technology. High squeezing enables large transmission bandwidth and strong anonymity, and the topological nature of the state enables local error mitigation. {\\copyright} 2018 American Physical Society.},\n\tart_number = {032345},\n\tauthor = {Menicucci, N.C. and Baragiola, B.Q. and Demarie, T.F. and Brennen, G.K.},\n\tdoi = {10.1103/PhysRevA.97.032345},\n\tjournal = {Physical Review A},\n\tnumber = {3},\n\ttitle = {Anonymous broadcasting of classical information with a continuous-variable topological quantum code},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044971741&doi=10.1103%2fPhysRevA.97.032345&partnerID=40&md5=44e0b5a418fa99bc3ad8626acc4a202d},\n\tvolume = {97},\n\tyear = {2018},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044971741&doi=10.1103%2fPhysRevA.97.032345&partnerID=40&md5=44e0b5a418fa99bc3ad8626acc4a202d},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.97.032345}}\n\n
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\n Broadcasting information anonymously becomes more difficult as surveillance technology improves, but remarkably, quantum protocols exist that enable provably traceless broadcasting. The difficulty is making scalable entangled resource states that are robust to errors. We propose an anonymous broadcasting protocol that uses a continuous-variable surface-code state that can be produced using current technology. High squeezing enables large transmission bandwidth and strong anonymity, and the topological nature of the state enables local error mitigation. © 2018 American Physical Society.\n
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\n \n\n \n \n \n \n \n \n Sound Clocks and Sonic Relativity.\n \n \n \n \n\n\n \n Todd, S.; and Menicucci, N.\n\n\n \n\n\n\n Foundations of Physics, 47(10). 2017.\n \n\n\n\n
\n\n\n\n \n \n \"Sound link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Todd20171267,\n\tabstract = {Sound propagation within certain non-relativistic condensed matter models obeys a relativistic wave equation despite such systems admitting entirely non-relativistic descriptions. A natural question that arises upon consideration of this is, "do devices exist that will experience the relativity in these systems?" We describe a thought experiment in which `acoustic observers\\' possess devices called sound clocks that can be connected to form chains. Careful investigation shows that appropriately constructed chains of stationary and moving sound clocks are perceived by observers on the other chain as undergoing the relativistic phenomena of length contraction and time dilation by the Lorentz factor, γ, with c the speed of sound. Sound clocks within moving chains actually tick less frequently than stationary ones and must be separated by a shorter distance than when stationary to satisfy simultaneity conditions. Stationary sound clocks appear to be length contracted and time dilated to moving observers due to their misunderstanding of their own state of motion with respect to the laboratory. Observers restricted to using sound clocks describe a universe kinematically consistent with the theory of special relativity, despite the preferred frame of their universe in the laboratory. Such devices show promise in further probing analogue relativity models, for example in investigating phenomena that require careful consideration of the proper time elapsed for observers. {\\copyright} 2017, The Author(s).},\n\tart_number = {1267-1293},\n\tauthor = {Todd, S.L. and Menicucci, N.C.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-19 16:34:55 +1100},\n\tdoi = {10.1007/s10701-017-0109-0},\n\tjournal = {Foundations of Physics},\n\tnumber = {10},\n\ttitle = {Sound Clocks and Sonic Relativity},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026827974&doi=10.1007%2fs10701-017-0109-0&partnerID=40&md5=c4581614c608094c203403d38ea5590b},\n\tvolume = {47},\n\tyear = {2017},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026827974&doi=10.1007%2fs10701-017-0109-0&partnerID=40&md5=c4581614c608094c203403d38ea5590b},\n\tBdsk-Url-2 = {https://doi.org/10.1007/s10701-017-0109-0}}\n\n
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\n Sound propagation within certain non-relativistic condensed matter models obeys a relativistic wave equation despite such systems admitting entirely non-relativistic descriptions. A natural question that arises upon consideration of this is, \"do devices exist that will experience the relativity in these systems?\" We describe a thought experiment in which `acoustic observers ́possess devices called sound clocks that can be connected to form chains. Careful investigation shows that appropriately constructed chains of stationary and moving sound clocks are perceived by observers on the other chain as undergoing the relativistic phenomena of length contraction and time dilation by the Lorentz factor, γ, with c the speed of sound. Sound clocks within moving chains actually tick less frequently than stationary ones and must be separated by a shorter distance than when stationary to satisfy simultaneity conditions. Stationary sound clocks appear to be length contracted and time dilated to moving observers due to their misunderstanding of their own state of motion with respect to the laboratory. Observers restricted to using sound clocks describe a universe kinematically consistent with the theory of special relativity, despite the preferred frame of their universe in the laboratory. Such devices show promise in further probing analogue relativity models, for example in investigating phenomena that require careful consideration of the proper time elapsed for observers. © 2017, The Author(s).\n
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\n \n\n \n \n \n \n \n \n Measurement-Based Linear Optics.\n \n \n \n \n\n\n \n Alexander, R.; Gabay, N.; Rohde, P.; and Menicucci, N.\n\n\n \n\n\n\n Physical Review Letters, 118(11). 2017.\n \n\n\n\n
\n\n\n\n \n \n \"Measurement-Based link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{Alexander2017,\n\tabstract = {A major challenge in optical quantum processing is implementing large, stable interferometers. We offer a novel approach: virtual, measurement-based interferometers that are programed on the fly solely by the choice of homodyne measurement angles. The effects of finite squeezing are captured as uniform amplitude damping. We compare our proposal to existing (physical) interferometers and consider its performance for BosonSampling, which could demonstrate postclassical computational power in the near future. We prove its efficiency in time and squeezing (energy) in this setting. {\\copyright} 2017 American Physical Society.},\n\tart_number = {110503},\n\tauthor = {Alexander, R.N. and Gabay, N.C. and Rohde, P.P. and Menicucci, N.C.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1103/PhysRevLett.118.110503},\n\tjournal = {Physical Review Letters},\n\tnumber = {11},\n\ttitle = {Measurement-Based Linear Optics},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015791502&doi=10.1103%2fPhysRevLett.118.110503&partnerID=40&md5=fba5693637c08c175e0f5fdb55ab4a46},\n\tvolume = {118},\n\tyear = {2017},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015791502&doi=10.1103%2fPhysRevLett.118.110503&partnerID=40&md5=fba5693637c08c175e0f5fdb55ab4a46},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevLett.118.110503}}\n\n
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\n A major challenge in optical quantum processing is implementing large, stable interferometers. We offer a novel approach: virtual, measurement-based interferometers that are programed on the fly solely by the choice of homodyne measurement angles. The effects of finite squeezing are captured as uniform amplitude damping. We compare our proposal to existing (physical) interferometers and consider its performance for BosonSampling, which could demonstrate postclassical computational power in the near future. We prove its efficiency in time and squeezing (energy) in this setting. © 2017 American Physical Society.\n
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\n \n\n \n \n \n \n \n \n Flow ambiguity: A path towards classically driven blind quantum computation.\n \n \n \n \n\n\n \n Mantri, A.; Demarie, T.; Menicucci, N.; and Fitzsimons, J.\n\n\n \n\n\n\n Physical Review X, 7(3). 2017.\n \n\n\n\n
\n\n\n\n \n \n \"Flow link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{Mantri2017,\n\tabstract = {Blind quantumcomputation protocols allowa user to delegate a computation to a remote quantum computer in such a way that the privacy of their computation is preserved, even from the device implementing the computation. To date, such protocols are only known for settings involving at least two quantumdevices: either a user with some quantum capabilities and a remote quantum server or two or more entangled but noncommunicating servers. In this work, we take the first step towards the construction of a blind quantum computing protocol with a completely classical client and single quantum server. Specifically, we show how a classical client can exploit the ambiguity in the flowof information inmeasurement-based quantumcomputing to construct a protocol for hiding critical aspects of a computation delegated to a remote quantum computer. This ambiguity arises due to the fact that, for a fixed graph, there existmultiple choices of the input and output vertex sets that result in deterministic measurement patterns consistent with the same fixed total ordering of vertices. This allows a classical user, computing only measurement angles, to drive a measurement-based computation performed on a remote device while hiding critical aspects of the computation.},\n\tart_number = {031004},\n\tauthor = {Mantri, A. and Demarie, T.F. and Menicucci, N.C. and Fitzsimons, J.F.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1103/PhysRevX.7.031004},\n\tjournal = {Physical Review X},\n\tnumber = {3},\n\ttitle = {Flow ambiguity: A path towards classically driven blind quantum computation},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85025129082&doi=10.1103%2fPhysRevX.7.031004&partnerID=40&md5=dff5bb81665d5cfea40b6cbcc4ce7c7e},\n\tvolume = {7},\n\tyear = {2017},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85025129082&doi=10.1103%2fPhysRevX.7.031004&partnerID=40&md5=dff5bb81665d5cfea40b6cbcc4ce7c7e},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevX.7.031004}}\n\n
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\n Blind quantumcomputation protocols allowa user to delegate a computation to a remote quantum computer in such a way that the privacy of their computation is preserved, even from the device implementing the computation. To date, such protocols are only known for settings involving at least two quantumdevices: either a user with some quantum capabilities and a remote quantum server or two or more entangled but noncommunicating servers. In this work, we take the first step towards the construction of a blind quantum computing protocol with a completely classical client and single quantum server. Specifically, we show how a classical client can exploit the ambiguity in the flowof information inmeasurement-based quantumcomputing to construct a protocol for hiding critical aspects of a computation delegated to a remote quantum computer. This ambiguity arises due to the fact that, for a fixed graph, there existmultiple choices of the input and output vertex sets that result in deterministic measurement patterns consistent with the same fixed total ordering of vertices. This allows a classical user, computing only measurement angles, to drive a measurement-based computation performed on a remote device while hiding critical aspects of the computation.\n
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\n \n\n \n \n \n \n \n \n Encoding qubits into oscillators with atomic ensembles and squeezed light.\n \n \n \n \n\n\n \n Motes, K.; Baragiola, B.; Gilchrist, A.; and Menicucci, N.\n\n\n \n\n\n\n Physical Review A, 95(5). 2017.\n \n\n\n\n
\n\n\n\n \n \n \"Encoding link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{Motes2017,\n\tabstract = {The Gottesman-Kitaev-Preskill (GKP) encoding of a qubit within an oscillator provides a number of advantages when used in a fault-tolerant architecture for quantum computing, most notably that Gaussian operations suffice to implement all single- and two-qubit Clifford gates. The main drawback of the encoding is that the logical states themselves are challenging to produce. Here we present a method for generating optical GKP-encoded qubits by coupling an atomic ensemble to a squeezed state of light. Particular outcomes of a subsequent spin measurement of the ensemble herald successful generation of the resource state in the optical mode. We analyze the method in terms of the resources required (total spin and amount of squeezing) and the probability of success. We propose a physical implementation using a Faraday-based quantum nondemolition interaction. {\\copyright} 2017 American Physical Society.},\n\tart_number = {053819},\n\tauthor = {Motes, K.R. and Baragiola, B.Q. and Gilchrist, A. and Menicucci, N.C.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1103/PhysRevA.95.053819},\n\tjournal = {Physical Review A},\n\tnumber = {5},\n\ttitle = {Encoding qubits into oscillators with atomic ensembles and squeezed light},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026896360&doi=10.1103%2fPhysRevA.95.053819&partnerID=40&md5=5e340fd10e89c2021a0a92737ab73225},\n\tvolume = {95},\n\tyear = {2017},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026896360&doi=10.1103%2fPhysRevA.95.053819&partnerID=40&md5=5e340fd10e89c2021a0a92737ab73225},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.95.053819}}\n\n
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\n The Gottesman-Kitaev-Preskill (GKP) encoding of a qubit within an oscillator provides a number of advantages when used in a fault-tolerant architecture for quantum computing, most notably that Gaussian operations suffice to implement all single- and two-qubit Clifford gates. The main drawback of the encoding is that the logical states themselves are challenging to produce. Here we present a method for generating optical GKP-encoded qubits by coupling an atomic ensemble to a squeezed state of light. Particular outcomes of a subsequent spin measurement of the ensemble herald successful generation of the resource state in the optical mode. We analyze the method in terms of the resources required (total spin and amount of squeezing) and the probability of success. We propose a physical implementation using a Faraday-based quantum nondemolition interaction. © 2017 American Physical Society.\n
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\n \n\n \n \n \n \n \n \n Do event horizons exist?.\n \n \n \n \n\n\n \n Baccetti, V.; Mann, R.; and Terno, D.\n\n\n \n\n\n\n International Journal of Modern Physics D, 26(12). 2017.\n \n\n\n\n
\n\n\n\n \n \n \"Do link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Baccetti2017,\n\tabstract = {Event horizons are the defining feature of classical black holes. They are the key ingredient of the information loss paradox which, as paradoxes in quantum foundations, is built on a combination of predictions of quantum theory and counterfactual classical features: neither horizon formation nor its crossing by a test body can be detected by a distant observer. Furthermore, horizons are unnecessary for the production of Hawking-like radiation. We demonstrate that when this radiation is taken into account, it can prevent horizon crossing/formation in a large class of models. We conjecture that horizon avoidance is a general feature of collapse. The nonexistence of event horizons dispels the paradox, but opens up important questions about thermodynamic properties of the resulting objects and correlations between different degrees of freedom. {\\copyright} 2017 World Scientific Publishing Company.},\n\tart_number = {1743008},\n\tauthor = {Baccetti, V. and Mann, R.B. and Terno, D.R.},\n\tdate-added = {2019-03-18 11:59:12 +1100},\n\tdate-modified = {2019-03-18 11:59:12 +1100},\n\tdoi = {10.1142/S0218271817430088},\n\tjournal = {International Journal of Modern Physics D},\n\tnumber = {12},\n\ttitle = {Do event horizons exist?},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032881477&doi=10.1142%2fS0218271817430088&partnerID=40&md5=3606b91ab04dc3b0549f4d3e0ed32aee},\n\tvolume = {26},\n\tyear = {2017},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032881477&doi=10.1142%2fS0218271817430088&partnerID=40&md5=3606b91ab04dc3b0549f4d3e0ed32aee},\n\tBdsk-Url-2 = {https://doi.org/10.1142/S0218271817430088}}\n\n
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\n Event horizons are the defining feature of classical black holes. They are the key ingredient of the information loss paradox which, as paradoxes in quantum foundations, is built on a combination of predictions of quantum theory and counterfactual classical features: neither horizon formation nor its crossing by a test body can be detected by a distant observer. Furthermore, horizons are unnecessary for the production of Hawking-like radiation. We demonstrate that when this radiation is taken into account, it can prevent horizon crossing/formation in a large class of models. We conjecture that horizon avoidance is a general feature of collapse. The nonexistence of event horizons dispels the paradox, but opens up important questions about thermodynamic properties of the resulting objects and correlations between different degrees of freedom. © 2017 World Scientific Publishing Company.\n
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\n \n\n \n \n \n \n \n \n The information recovery problem.\n \n \n \n \n\n\n \n Baccetti, V.; Husain, V.; and Terno, D.\n\n\n \n\n\n\n Entropy, 19(1). 2017.\n \n\n\n\n
\n\n\n\n \n \n \"The link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Baccetti2017,\n\tabstract = {The issue of unitary evolution during creation and evaporation of a black hole remains controversial. We argue that some prominent cures are more troubling than the disease, demonstrate that their central element-forming of the event horizon before the evaporation begins-is not necessarily true, and describe a fully coupled matter-gravity system which is manifestly unitary. {\\copyright} 2016 by the authors.},\n\tart_number = {17},\n\tauthor = {Baccetti, V. and Husain, V. and Terno, D.R.},\n\tdate-added = {2019-03-18 11:59:12 +1100},\n\tdate-modified = {2019-03-18 11:59:12 +1100},\n\tdoi = {10.3390/e19010017},\n\tjournal = {Entropy},\n\tnumber = {1},\n\ttitle = {The information recovery problem},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009292216&doi=10.3390%2fe19010017&partnerID=40&md5=ec8ff8270f3e103ec3ef9e90c61ba495},\n\tvolume = {19},\n\tyear = {2017},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009292216&doi=10.3390%2fe19010017&partnerID=40&md5=ec8ff8270f3e103ec3ef9e90c61ba495},\n\tBdsk-Url-2 = {https://doi.org/10.3390/e19010017}}\n\n
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\n The issue of unitary evolution during creation and evaporation of a black hole remains controversial. We argue that some prominent cures are more troubling than the disease, demonstrate that their central element-forming of the event horizon before the evaporation begins-is not necessarily true, and describe a fully coupled matter-gravity system which is manifestly unitary. © 2016 by the authors.\n
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\n \n\n \n \n \n \n \n \n Room-temperature spontaneous superradiance from single diamond nanocrystals.\n \n \n \n \n\n\n \n Bradac, C.; Johnsson, M.; Van Breugel, M.; Baragiola, B.; Martin, R.; Juan, M.; Brennen, G.; and Volz, T.\n\n\n \n\n\n\n Nature Communications, 8(1). 2017.\n \n\n\n\n
\n\n\n\n \n \n \"Room-temperature link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Bradac2017,\n\tabstract = {Superradiance (SR) is a cooperative phenomenon which occurs when an ensemble of quantum emitters couples collectively to a mode of the electromagnetic field as a single, massive dipole that radiates photons at an enhanced rate. Previous studies on solid-state systems either reported SR from sizeable crystals with at least one spatial dimension much larger than the wavelength of the light and/or only close to liquid-helium temperatures. Here, we report the observation of room-temperature superradiance from single, highly luminescent diamond nanocrystals with spatial dimensions much smaller than the wavelength of light, and each containing a large number (∼103) of embedded nitrogen-vacancy (NV) centres. The results pave the way towards a systematic study of SR in a well-controlled, solid-state quantum system at room temperature. {\\copyright} 2017 The Author(s).},\n\tart_number = {1205},\n\tauthor = {Bradac, C. and Johnsson, M.T. and Van Breugel, M. and Baragiola, B.Q. and Martin, R. and Juan, M.L. and Brennen, G.K. and Volz, T.},\n\tdoi = {10.1038/s41467-017-01397-4},\n\tjournal = {Nature Communications},\n\tnumber = {1},\n\ttitle = {Room-temperature spontaneous superradiance from single diamond nanocrystals},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032616556&doi=10.1038%2fs41467-017-01397-4&partnerID=40&md5=2515c0230cab3e99eaefe019d6f31fa6},\n\tvolume = {8},\n\tyear = {2017},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032616556&doi=10.1038%2fs41467-017-01397-4&partnerID=40&md5=2515c0230cab3e99eaefe019d6f31fa6},\n\tBdsk-Url-2 = {https://doi.org/10.1038/s41467-017-01397-4}}\n\n
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\n Superradiance (SR) is a cooperative phenomenon which occurs when an ensemble of quantum emitters couples collectively to a mode of the electromagnetic field as a single, massive dipole that radiates photons at an enhanced rate. Previous studies on solid-state systems either reported SR from sizeable crystals with at least one spatial dimension much larger than the wavelength of the light and/or only close to liquid-helium temperatures. Here, we report the observation of room-temperature superradiance from single, highly luminescent diamond nanocrystals with spatial dimensions much smaller than the wavelength of light, and each containing a large number (∼103) of embedded nitrogen-vacancy (NV) centres. The results pave the way towards a systematic study of SR in a well-controlled, solid-state quantum system at room temperature. © 2017 The Author(s).\n
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\n \n\n \n \n \n \n \n \n Quantum trajectories for propagating Fock states.\n \n \n \n \n\n\n \n Baragiola, B.; and Combes, J.\n\n\n \n\n\n\n Physical Review A, 96(2). 2017.\n \n\n\n\n
\n\n\n\n \n \n \"Quantum link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Baragiola2017,\n\tabstract = {We derive quantum trajectories (also known as stochastic master equations) that describe an arbitrary quantum system probed by a propagating wave packet of light prepared in a continuous-mode Fock state. We consider three detection schemes of the output light: photon counting, homodyne detection, and heterodyne detection. We generalize to input field states in superpositions and mixtures of Fock states and illustrate our formalism with several examples. {\\copyright} 2017 American Physical Society.},\n\tart_number = {023819},\n\tauthor = {Baragiola, B.Q. and Combes, J.},\n\tdoi = {10.1103/PhysRevA.96.023819},\n\tjournal = {Physical Review A},\n\tnumber = {2},\n\ttitle = {Quantum trajectories for propagating Fock states},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028649065&doi=10.1103%2fPhysRevA.96.023819&partnerID=40&md5=8a17c864c0a3a3aeb07aa6cb7992d5bf},\n\tvolume = {96},\n\tyear = {2017},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028649065&doi=10.1103%2fPhysRevA.96.023819&partnerID=40&md5=8a17c864c0a3a3aeb07aa6cb7992d5bf},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.96.023819}}\n\n
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\n We derive quantum trajectories (also known as stochastic master equations) that describe an arbitrary quantum system probed by a propagating wave packet of light prepared in a continuous-mode Fock state. We consider three detection schemes of the output light: photon counting, homodyne detection, and heterodyne detection. We generalize to input field states in superpositions and mixtures of Fock states and illustrate our formalism with several examples. © 2017 American Physical Society.\n
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\n \n\n \n \n \n \n \n \n Passive interferometric symmetries of multimode Gaussian pure states.\n \n \n \n \n\n\n \n Gabay, N.; and Menicucci, N.\n\n\n \n\n\n\n Physical Review A, 93(5). 2016.\n \n\n\n\n
\n\n\n\n \n \n \"Passive link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Gabay2016,\n\tabstract = {As large-scale multimode Gaussian states begin to become accessible in the laboratory, their representation and analysis become a useful topic of research in their own right. The graphical calculus for Gaussian pure states provides powerful tools for their representation, while this work presents a useful tool for their analysis: passive interferometric (i.e., number-conserving) symmetries. Here we show that these symmetries of multimode Gaussian states simplify calculations in measurement-based quantum computing and provide constructive tools for engineering large-scale harmonic systems with specific physical properties, and we provide a general mathematical framework for deriving them. Such symmetries are generated by linear combinations of operators expressed in the Schwinger representation of U(2), called nullifiers because the Gaussian state in question is a zero eigenstate of them. This general framework is shown to have applications in the noise analysis of continuous-various cluster states and is expected to have additional applications in future work with large-scale multimode Gaussian states. {\\copyright} 2016 American Physical Society.},\n\tart_number = {052326},\n\tauthor = {Gabay, N. and Menicucci, N.C.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1103/PhysRevA.93.052326},\n\tjournal = {Physical Review A},\n\tnumber = {5},\n\ttitle = {Passive interferometric symmetries of multimode Gaussian pure states},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84969884902&doi=10.1103%2fPhysRevA.93.052326&partnerID=40&md5=2adf55faf91d4e59cf0d52accdaa1bf6},\n\tvolume = {93},\n\tyear = {2016},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84969884902&doi=10.1103%2fPhysRevA.93.052326&partnerID=40&md5=2adf55faf91d4e59cf0d52accdaa1bf6},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.93.052326}}\n\n
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\n\n\n
\n As large-scale multimode Gaussian states begin to become accessible in the laboratory, their representation and analysis become a useful topic of research in their own right. The graphical calculus for Gaussian pure states provides powerful tools for their representation, while this work presents a useful tool for their analysis: passive interferometric (i.e., number-conserving) symmetries. Here we show that these symmetries of multimode Gaussian states simplify calculations in measurement-based quantum computing and provide constructive tools for engineering large-scale harmonic systems with specific physical properties, and we provide a general mathematical framework for deriving them. Such symmetries are generated by linear combinations of operators expressed in the Schwinger representation of U(2), called nullifiers because the Gaussian state in question is a zero eigenstate of them. This general framework is shown to have applications in the noise analysis of continuous-various cluster states and is expected to have additional applications in future work with large-scale multimode Gaussian states. © 2016 American Physical Society.\n
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\n \n\n \n \n \n \n \n \n One-way quantum computing with arbitrarily large time-frequency continuous-variable cluster states from a single optical parametric oscillator.\n \n \n \n \n\n\n \n Alexander, R.; Wang, P.; Sridhar, N.; Chen, M.; Pfister, O.; and Menicucci, N.\n\n\n \n\n\n\n Physical Review A, 94(3). 2016.\n \n\n\n\n
\n\n\n\n \n \n \"One-way link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Alexander2016,\n\tabstract = {One-way quantum computing is experimentally appealing because it requires only local measurements on an entangled resource called a cluster state. Record-size, but nonuniversal, continuous-variable cluster states were recently demonstrated separately in the time and frequency domains. We propose to combine these approaches into a scalable architecture in which a single optical parametric oscillator and simple interferometer entangle up to (3×103 frequencies) × (unlimited number of temporal modes) into a computationally universal continuous-variable cluster state. We introduce a generalized measurement protocol to enable improved computational performance on this entanglement resource. {\\copyright} 2016 American Physical Society.},\n\tart_number = {032327},\n\tauthor = {Alexander, R.N. and Wang, P. and Sridhar, N. and Chen, M. and Pfister, O. and Menicucci, N.C.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1103/PhysRevA.94.032327},\n\tjournal = {Physical Review A},\n\tnumber = {3},\n\ttitle = {One-way quantum computing with arbitrarily large time-frequency continuous-variable cluster states from a single optical parametric oscillator},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84989246413&doi=10.1103%2fPhysRevA.94.032327&partnerID=40&md5=532c2bc00d7bb4991b420d559cf3b25e},\n\tvolume = {94},\n\tyear = {2016},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84989246413&doi=10.1103%2fPhysRevA.94.032327&partnerID=40&md5=532c2bc00d7bb4991b420d559cf3b25e},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.94.032327}}\n\n
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\n\n\n
\n One-way quantum computing is experimentally appealing because it requires only local measurements on an entangled resource called a cluster state. Record-size, but nonuniversal, continuous-variable cluster states were recently demonstrated separately in the time and frequency domains. We propose to combine these approaches into a scalable architecture in which a single optical parametric oscillator and simple interferometer entangle up to (3×103 frequencies) × (unlimited number of temporal modes) into a computationally universal continuous-variable cluster state. We introduce a generalized measurement protocol to enable improved computational performance on this entanglement resource. © 2016 American Physical Society.\n
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\n \n\n \n \n \n \n \n \n Flexible quantum circuits using scalable continuous-variable cluster states.\n \n \n \n \n\n\n \n Alexander, R.; and Menicucci, N.\n\n\n \n\n\n\n Physical Review A, 93(6). 2016.\n \n\n\n\n
\n\n\n\n \n \n \"Flexible link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Alexander2016,\n\tabstract = {We show that measurement-based quantum computation on scalable continuous-variable (CV) cluster states admits more quantum-circuit flexibility and compactness than similar protocols for standard square-lattice CV cluster states. This advantage is a direct result of the macronode structure of these states - that is, a lattice structure in which each graph node actually consists of several physical modes. These extra modes provide additional measurement degrees of freedom at each graph location, which can be used to manipulate the flow and processing of quantum information more robustly and with additional flexibility that is not available on an ordinary lattice. {\\copyright} 2016 American Physical Society.},\n\tart_number = {062326},\n\tauthor = {Alexander, R.N. and Menicucci, N.C.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1103/PhysRevA.93.062326},\n\tjournal = {Physical Review A},\n\tnumber = {6},\n\ttitle = {Flexible quantum circuits using scalable continuous-variable cluster states},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977584094&doi=10.1103%2fPhysRevA.93.062326&partnerID=40&md5=b53ab3463dbd89237e21bc2434d1a4a6},\n\tvolume = {93},\n\tyear = {2016},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977584094&doi=10.1103%2fPhysRevA.93.062326&partnerID=40&md5=b53ab3463dbd89237e21bc2434d1a4a6},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.93.062326}}\n\n
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\n We show that measurement-based quantum computation on scalable continuous-variable (CV) cluster states admits more quantum-circuit flexibility and compactness than similar protocols for standard square-lattice CV cluster states. This advantage is a direct result of the macronode structure of these states - that is, a lattice structure in which each graph node actually consists of several physical modes. These extra modes provide additional measurement degrees of freedom at each graph location, which can be used to manipulate the flow and processing of quantum information more robustly and with additional flexibility that is not available on an ordinary lattice. © 2016 American Physical Society.\n
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\n \n\n \n \n \n \n \n \n Dispersive response of atoms trapped near the surface of an optical nanofiber with applications to quantum nondemolition measurement and spin squeezing.\n \n \n \n \n\n\n \n Qi, X.; Baragiola, B.; Jessen, P.; and Deutsch, I.\n\n\n \n\n\n\n Physical Review A, 93(2). 2016.\n \n\n\n\n
\n\n\n\n \n \n \"Dispersive link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Qi2016,\n\tabstract = {We study the strong coupling between photons and atoms that can be achieved in an optical nanofiber geometry when the interaction is dispersive. While the Purcell enhancement factor for spontaneous emission into the guided mode does not reach the strong-coupling regime for individual atoms, one can obtain high cooperativity for ensembles of a few thousand atoms due to the tight confinement of the guided modes and constructive interference over the entire chain of trapped atoms. We calculate the dyadic Green\\'s function, which determines the scattering of light by atoms in the presence of the fiber, and thus the phase shift and polarization rotation induced on the guided light by the trapped atoms. The Green\\'s function is related to a full Heisenberg-Langevin treatment of the dispersive response of the quantized field to tensor polarizable atoms. We apply our formalism to quantum nondemolition (QND) measurement of the atoms via polarimetry. We study shot-noise-limited detection of atom number for atoms in a completely mixed spin state and the squeezing of projection noise for atoms in clock states. Compared with squeezing of atomic ensembles in free space, we capitalize on unique features that arise in the nanofiber geometry including anisotropy of both the intensity and polarization of the guided modes. We use a first-principles stochastic master equation to model the squeezing as a function of time in the presence of decoherence due to optical pumping. We find a peak metrological squeezing of ∼5 dB is achievable with current technology for ∼2500 atoms trapped 180 nm from the surface of a nanofiber with radius a=225 nm. {\\copyright} 2016 American Physical Society.},\n\tart_number = {023817},\n\tauthor = {Qi, X. and Baragiola, B.Q. and Jessen, P.S. and Deutsch, I.H.},\n\tdoi = {10.1103/PhysRevA.93.023817},\n\tjournal = {Physical Review A},\n\tnumber = {2},\n\ttitle = {Dispersive response of atoms trapped near the surface of an optical nanofiber with applications to quantum nondemolition measurement and spin squeezing},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957998727&doi=10.1103%2fPhysRevA.93.023817&partnerID=40&md5=4c9f88627f78068f9dfb3de2a2ca1cdf},\n\tvolume = {93},\n\tyear = {2016},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957998727&doi=10.1103%2fPhysRevA.93.023817&partnerID=40&md5=4c9f88627f78068f9dfb3de2a2ca1cdf},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.93.023817}}\n\n
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\n We study the strong coupling between photons and atoms that can be achieved in an optical nanofiber geometry when the interaction is dispersive. While the Purcell enhancement factor for spontaneous emission into the guided mode does not reach the strong-coupling regime for individual atoms, one can obtain high cooperativity for ensembles of a few thousand atoms due to the tight confinement of the guided modes and constructive interference over the entire chain of trapped atoms. We calculate the dyadic Greenś function, which determines the scattering of light by atoms in the presence of the fiber, and thus the phase shift and polarization rotation induced on the guided light by the trapped atoms. The Greenś function is related to a full Heisenberg-Langevin treatment of the dispersive response of the quantized field to tensor polarizable atoms. We apply our formalism to quantum nondemolition (QND) measurement of the atoms via polarimetry. We study shot-noise-limited detection of atom number for atoms in a completely mixed spin state and the squeezing of projection noise for atoms in clock states. Compared with squeezing of atomic ensembles in free space, we capitalize on unique features that arise in the nanofiber geometry including anisotropy of both the intensity and polarization of the guided modes. We use a first-principles stochastic master equation to model the squeezing as a function of time in the presence of decoherence due to optical pumping. We find a peak metrological squeezing of ∼5 dB is achievable with current technology for ∼2500 atoms trapped 180 nm from the surface of a nanofiber with radius a=225 nm. © 2016 American Physical Society.\n
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\n \n\n \n \n \n \n \n \n Cooperatively-enhanced atomic dipole forces in optically trapped nanodiamonds containing NV centres, in liquid.\n \n \n \n \n\n\n \n Bradac, C.; Juan, M.; Johnsson, M.; Besga, B.; Van Breugel, M.; Baragiola, B.; Martin, R.; Brennen, G.; Molina-Terriza, G.; and Volz, T.\n\n\n \n\n\n\n 2016.\n \n\n\n\n
\n\n\n\n \n \n \"Cooperatively-enhanced link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@conference{Bradac2016,\n\tart_number = {1001334},\n\tauthor = {Bradac, C. and Juan, M.L. and Johnsson, M. and Besga, B. and Van Breugel, M. and Baragiola, B. and Martin, R. and Brennen, G. and Molina-Terriza, G. and Volz, T.},\n\tdoi = {10.1117/12.2242963},\n\tjournal = {Proceedings of SPIE - The International Society for Optical Engineering},\n\ttitle = {Cooperatively-enhanced atomic dipole forces in optically trapped nanodiamonds containing NV centres, in liquid},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011416533&doi=10.1117%2f12.2242963&partnerID=40&md5=1fb3800e11f331ea707549e6ece6032b},\n\tvolume = {10013},\n\tyear = {2016},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011416533&doi=10.1117%2f12.2242963&partnerID=40&md5=1fb3800e11f331ea707549e6ece6032b},\n\tBdsk-Url-2 = {https://doi.org/10.1117/12.2242963}}\n\n
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\n  \n 2015\n \n \n (2)\n \n \n
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\n \n\n \n \n \n \n \n \n Engineering large-scale entanglement in the quantum optical frequency comb.\n \n \n \n \n\n\n \n Wang, P.; Fan, W.; Chen, M.; Pfister, O.; and Menicucci, N.\n\n\n \n\n\n\n 2015.\n \n\n\n\n
\n\n\n\n \n \n \"Engineering link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@conference{Wang20151551p,\n\tabstract = {We report on experimental progress toward scaling our recent 60-entangledqumode experiment [1] to thousands of qumodes in the quantum optical frequency comb. We present a model which predicts that 3,200 entangled modes can be achieved. {\\copyright} 2014 Optical Society of America.},\n\tart_number = {1551p},\n\tauthor = {Wang, P. and Fan, W. and Chen, M. and Pfister, O. and Menicucci, N.C.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-21 16:16:37 +1100},\n\tdoi = {10.1364/CLEO_QELS.2015.FTh1A.5},\n\tjournal = {CLEO: QELS - Fundamental Science, CLEO_QELS 2015},\n\ttitle = {Engineering large-scale entanglement in the quantum optical frequency comb},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84935063455&doi=10.1364%2fCLEO_QELS.2015.FTh1A.5&partnerID=40&md5=f209103bd403c3dc72c0bc824159f3fd},\n\tyear = {2015},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84935063455&doi=10.1364%2fCLEO_QELS.2015.FTh1A.5&partnerID=40&md5=f209103bd403c3dc72c0bc824159f3fd},\n\tBdsk-Url-2 = {https://doi.org/10.1364/CLEO_QELS.2015.FTh1A.5}}\n\n
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\n We report on experimental progress toward scaling our recent 60-entangledqumode experiment [1] to thousands of qumodes in the quantum optical frequency comb. We present a model which predicts that 3,200 entangled modes can be achieved. © 2014 Optical Society of America.\n
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\n \n\n \n \n \n \n \n \n Acceleration-assisted entanglement harvesting and rangefinding.\n \n \n \n \n\n\n \n Salton, G.; Mann, R.; and Menicucci, N.\n\n\n \n\n\n\n New Journal of Physics, 17. 2015.\n \n\n\n\n
\n\n\n\n \n \n \"Acceleration-assisted link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Salton2015,\n\tabstract = {We study entanglement harvested from a quantum field through local interaction with Unruh-DeWitt detectors undergoing linear acceleration. The interactions allow entanglement to be swapped locally from the field to the detectors. We find an enhancement in the entanglement harvesting by two detectors with anti-parallel acceleration over those with inertialmotion. This enhancement is characterized by the presence of entanglement between two detectors that would otherwise maintain a separable state in the absence of relativistic motion (with the same distance of closest approach in both cases). We also find that entanglement harvesting is degraded for two detectors undergoing parallel acceleration in the same way as for two static, comoving detectors in a de Sitter universe. This degradation is known to be different from that of two inertial detectors in a thermal bath. We comment on the physical origin of the harvested entanglement and present three methods for determining distance between two detectors using properties of the harvested entanglement. Information about the separation is stored nonlocally in the joint state of the accelerated detectors after the interaction; a single detector alone contains none. We also find an example of entanglement sudden death exhibited in parameter space. {\\copyright}2015 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.},\n\tart_number = {035001},\n\tauthor = {Salton, G. and Mann, R.B. and Menicucci, N.C.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1088/1367-2630/17/3/035001},\n\tjournal = {New Journal of Physics},\n\ttitle = {Acceleration-assisted entanglement harvesting and rangefinding},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84928948293&doi=10.1088%2f1367-2630%2f17%2f3%2f035001&partnerID=40&md5=f5e73119f3a0fefabe88a240ee4f1dbc},\n\tvolume = {17},\n\tyear = {2015},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84928948293&doi=10.1088%2f1367-2630%2f17%2f3%2f035001&partnerID=40&md5=f5e73119f3a0fefabe88a240ee4f1dbc},\n\tBdsk-Url-2 = {https://doi.org/10.1088/1367-2630/17/3/035001}}\n\n
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\n We study entanglement harvested from a quantum field through local interaction with Unruh-DeWitt detectors undergoing linear acceleration. The interactions allow entanglement to be swapped locally from the field to the detectors. We find an enhancement in the entanglement harvesting by two detectors with anti-parallel acceleration over those with inertialmotion. This enhancement is characterized by the presence of entanglement between two detectors that would otherwise maintain a separable state in the absence of relativistic motion (with the same distance of closest approach in both cases). We also find that entanglement harvesting is degraded for two detectors undergoing parallel acceleration in the same way as for two static, comoving detectors in a de Sitter universe. This degradation is known to be different from that of two inertial detectors in a thermal bath. We comment on the physical origin of the harvested entanglement and present three methods for determining distance between two detectors using properties of the harvested entanglement. Information about the separation is stored nonlocally in the joint state of the accelerated detectors after the interaction; a single detector alone contains none. We also find an example of entanglement sudden death exhibited in parameter space. ©2015 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.\n
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\n  \n 2014\n \n \n (11)\n \n \n
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\n \n\n \n \n \n \n \n \n Weaving quantum optical frequency combs into hypercubic cluster states.\n \n \n \n \n\n\n \n Wang, P.; Chen, M.; Pfister, O.; and Menicucci, N.\n\n\n \n\n\n\n 2014.\n \n\n\n\n
\n\n\n\n \n \n \"Weaving link\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@conference{Wang2014,\n\tabstract = {We present a simple, scalable, top-down method for entangling the quantum optical frequency comb into hypercubic-lattice continuous-variable cluster states up to a maximum size of about 104 modes using existing technology. {\\copyright} 2014 Optical Society of America.},\n\tart_number = {6988631},\n\tauthor = {Wang, P. and Chen, M. and Pfister, O. and Menicucci, N.C.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tjournal = {Conference on Lasers and Electro-Optics Europe - Technical Digest},\n\ttitle = {Weaving quantum optical frequency combs into hypercubic cluster states},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84944712131&partnerID=40&md5=3deaa2a7f9ba5327001697f5218a0687},\n\tvolume = {2014-January},\n\tyear = {2014},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84944712131&partnerID=40&md5=3deaa2a7f9ba5327001697f5218a0687}}\n\n
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\n We present a simple, scalable, top-down method for entangling the quantum optical frequency comb into hypercubic-lattice continuous-variable cluster states up to a maximum size of about 104 modes using existing technology. © 2014 Optical Society of America.\n
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\n \n\n \n \n \n \n \n \n Weaving quantum optical frequency combs into continuous-variable hypercubic cluster states.\n \n \n \n \n\n\n \n Wang, P.; Chen, M.; Menicucci, N.; and Pfister, O.\n\n\n \n\n\n\n Physical Review A - Atomic, Molecular, and Optical Physics, 90(3). 2014.\n \n\n\n\n
\n\n\n\n \n \n \"Weaving link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Wang2014,\n\tabstract = {Cluster states with higher-dimensional lattices that cannot be physically embedded in three-dimensional space have important theoretical interest in quantum computation and quantum simulation of topologically ordered condensed-matter systems. We present a simple, scalable, top-down method of entangling the quantum optical frequency comb into hypercubic-lattice continuous-variable cluster states of a size of about 104 quantum field modes, using existing technology. A hypercubic lattice of dimension D (linear, square, cubic, hypercubic, etc.) requires but D optical parametric oscillators with bichromatic pumps whose frequency splittings alone determine the lattice dimensionality and the number of copies of the state. {\\copyright} 2014 American Physical Society.},\n\tart_number = {032325},\n\tauthor = {Wang, P. and Chen, M. and Menicucci, N.C. and Pfister, O.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1103/PhysRevA.90.032325},\n\tjournal = {Physical Review A - Atomic, Molecular, and Optical Physics},\n\tnumber = {3},\n\ttitle = {Weaving quantum optical frequency combs into continuous-variable hypercubic cluster states},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84907439120&doi=10.1103%2fPhysRevA.90.032325&partnerID=40&md5=63a880e88d791917bec0e004ad1eadf6},\n\tvolume = {90},\n\tyear = {2014},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84907439120&doi=10.1103%2fPhysRevA.90.032325&partnerID=40&md5=63a880e88d791917bec0e004ad1eadf6},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.90.032325}}\n\n
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\n Cluster states with higher-dimensional lattices that cannot be physically embedded in three-dimensional space have important theoretical interest in quantum computation and quantum simulation of topologically ordered condensed-matter systems. We present a simple, scalable, top-down method of entangling the quantum optical frequency comb into hypercubic-lattice continuous-variable cluster states of a size of about 104 quantum field modes, using existing technology. A hypercubic lattice of dimension D (linear, square, cubic, hypercubic, etc.) requires but D optical parametric oscillators with bichromatic pumps whose frequency splittings alone determine the lattice dimensionality and the number of copies of the state. © 2014 American Physical Society.\n
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\n \n\n \n \n \n \n \n \n Quantum seismology.\n \n \n \n \n\n\n \n Brown, E.; Donnelly, W.; Kempf, A.; Mann, R.; Martı́n-Martı́nez, E.; and Menicucci, N.\n\n\n \n\n\n\n New Journal of Physics, 16. 2014.\n \n\n\n\n
\n\n\n\n \n \n \"Quantum link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Brown2014,\n\tabstract = {We propose a quantum mechanical method of detecting weak vibrational disturbances inspired by the protocol of entanglement farming. We consider a setup where pairs of atoms in their ground state are successively sent through an optical cavity. It is known that in this way it is possible to drive that cavity toward a stable fixed-point state. Here we study how that fixed-point state depends on the time interval between pairs of atoms and on the distance between the cavitys mirrors. Taking advantage of an extremely precise resonance effect, we find that there are special values of these parameters where the fixed-point state is highly sensitive to perturbations, even harmonic vibrations with frequencies several orders of magnitude below the cavitys natural frequency. We propose that this sensitivity may be useful for high precision metrology. {\\copyright} 2014 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.},\n\tart_number = {105020},\n\tauthor = {Brown, E.G. and Donnelly, W. and Kempf, A. and Mann, R.B. and Mart{\\'\\i}n-Mart{\\'\\i}nez, E. and Menicucci, N.C.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1088/1367-2630/16/10/105020},\n\tjournal = {New Journal of Physics},\n\ttitle = {Quantum seismology},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84910138631&doi=10.1088%2f1367-2630%2f16%2f10%2f105020&partnerID=40&md5=890dc1b80f35f3a16eb808d0c65c87d2},\n\tvolume = {16},\n\tyear = {2014},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84910138631&doi=10.1088%2f1367-2630%2f16%2f10%2f105020&partnerID=40&md5=890dc1b80f35f3a16eb808d0c65c87d2},\n\tBdsk-Url-2 = {https://doi.org/10.1088/1367-2630/16/10/105020}}\n\n
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\n We propose a quantum mechanical method of detecting weak vibrational disturbances inspired by the protocol of entanglement farming. We consider a setup where pairs of atoms in their ground state are successively sent through an optical cavity. It is known that in this way it is possible to drive that cavity toward a stable fixed-point state. Here we study how that fixed-point state depends on the time interval between pairs of atoms and on the distance between the cavitys mirrors. Taking advantage of an extremely precise resonance effect, we find that there are special values of these parameters where the fixed-point state is highly sensitive to perturbations, even harmonic vibrations with frequencies several orders of magnitude below the cavitys natural frequency. We propose that this sensitivity may be useful for high precision metrology. © 2014 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.\n
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\n \n\n \n \n \n \n \n \n Noise analysis of single-mode Gaussian operations using continuous-variable cluster states.\n \n \n \n \n\n\n \n Alexander, R.; Armstrong, S.; Ukai, R.; and Menicucci, N.\n\n\n \n\n\n\n Physical Review A - Atomic, Molecular, and Optical Physics, 90(6). 2014.\n \n\n\n\n
\n\n\n\n \n \n \"Noise link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Alexander2014,\n\tabstract = {We consider measurement-based quantum computation that uses scalable continuous-variable cluster states with a one-dimensional topology. The physical resource, known here as the dual-rail quantum wire, can be generated using temporally multiplexed offline squeezing and linear optics or by using a single optical parametric oscillator. We focus on an important class of quantum gates, specifically Gaussian unitaries that act on single quantum modes (qumodes), which gives universal quantum computation when supplemented with multi-qumode operations and photon-counting measurements. The dual-rail wire supports two routes for applying single-qumode Gaussian unitaries: The first is to use traditional one-dimensional quantum-wire cluster-state measurement protocols. The second takes advantage of the dual-rail quantum wire in order to apply unitaries by measuring pairs of qumodes called macronodes. We analyze and compare these methods in terms of the suitability for implementing single-qumode Gaussian measurement-based quantum computation. {\\copyright} 2014 American Physical Society.},\n\tart_number = {062324},\n\tauthor = {Alexander, R.N. and Armstrong, S.C. and Ukai, R. and Menicucci, N.C.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1103/PhysRevA.90.062324},\n\tjournal = {Physical Review A - Atomic, Molecular, and Optical Physics},\n\tnumber = {6},\n\ttitle = {Noise analysis of single-mode Gaussian operations using continuous-variable cluster states},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84918793914&doi=10.1103%2fPhysRevA.90.062324&partnerID=40&md5=1eab1b12ed8273c0e713058198e09461},\n\tvolume = {90},\n\tyear = {2014},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84918793914&doi=10.1103%2fPhysRevA.90.062324&partnerID=40&md5=1eab1b12ed8273c0e713058198e09461},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.90.062324}}\n\n
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\n We consider measurement-based quantum computation that uses scalable continuous-variable cluster states with a one-dimensional topology. The physical resource, known here as the dual-rail quantum wire, can be generated using temporally multiplexed offline squeezing and linear optics or by using a single optical parametric oscillator. We focus on an important class of quantum gates, specifically Gaussian unitaries that act on single quantum modes (qumodes), which gives universal quantum computation when supplemented with multi-qumode operations and photon-counting measurements. The dual-rail wire supports two routes for applying single-qumode Gaussian unitaries: The first is to use traditional one-dimensional quantum-wire cluster-state measurement protocols. The second takes advantage of the dual-rail quantum wire in order to apply unitaries by measuring pairs of qumodes called macronodes. We analyze and compare these methods in terms of the suitability for implementing single-qumode Gaussian measurement-based quantum computation. © 2014 American Physical Society.\n
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\n \n\n \n \n \n \n \n \n Experimental generation of a 60-mode cluster state in the quantum optical frequency comb.\n \n \n \n \n\n\n \n Chen, M.; Menicucci, N.; and Pfister, O.\n\n\n \n\n\n\n 2014.\n \n\n\n\n
\n\n\n\n \n \n \"Experimental link\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@conference{Chen2014,\n\tabstract = {A 60-mode quantum-wire continuous-variable cluster state was experimentally generated in the quantum optical frequency comb of a single optical parametric oscillator. This is the largest entangled system ever created whose subsystems are all available simultaneously. {\\copyright} OSA 2014.},\n\tauthor = {Chen, M. and Menicucci, N.C. and Pfister, O.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tjournal = {Optics InfoBase Conference Papers},\n\ttitle = {Experimental generation of a 60-mode cluster state in the quantum optical frequency comb},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84899722791&partnerID=40&md5=2c1f7c64a19e418b2869ac91ff252192},\n\tyear = {2014},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84899722791&partnerID=40&md5=2c1f7c64a19e418b2869ac91ff252192}}\n\n
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\n A 60-mode quantum-wire continuous-variable cluster state was experimentally generated in the quantum optical frequency comb of a single optical parametric oscillator. This is the largest entangled system ever created whose subsystems are all available simultaneously. © OSA 2014.\n
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\n \n\n \n \n \n \n \n \n Detecting topological entanglement entropy in a lattice of quantum harmonic oscillators.\n \n \n \n \n\n\n \n Demarie, T.; Linjordet, T.; Menicucci, N.; and Brennen, G.\n\n\n \n\n\n\n New Journal of Physics, 16. 2014.\n \n\n\n\n
\n\n\n\n \n \n \"Detecting link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{Demarie2014,\n\tabstract = {The Kitaev surface code model is the most studied example of a topologically ordered phase and typically involves four-spin interactions on a two-dimensional surface. A universal signature of this phase is topological entanglement entropy (TEE), but due to low signal to noise, it is extremely difficult to observe in these systems, and one usually resorts to measuring anyonic statistics of excitations or non-local string operators to reveal the order. We describe a continuous-variable analog to the surface code using quantum harmonic oscillators on a two-dimensional lattice, which has the distinctive property of needing only two-body nearest-neighbor interactions for its creation. Though such a model is gapless, it satisfies an area law and the ground state can be simply prepared by measurements on a finitely squeezed and gapped two-dimensional cluster-state without topological order. Asymptotically, the continuous variable surface code TEE grows linearly with the squeezing parameter and a recently discovered non-local quantity, the topological logarithmic negativity, behaves analogously. We also show that the mixed-state generalization of the TEE, the topological mutual information, is robust to some forms of state preparation error and can be detected simply using single-mode quadrature measurements. Finally, we discuss scalable implementation of these methods using optical and circuit-QED technology. {\\copyright} 2014 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.},\n\tart_number = {085011},\n\tauthor = {Demarie, T.F. and Linjordet, T. and Menicucci, N.C. and Brennen, G.K.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1088/1367-2630/16/8/085011},\n\tjournal = {New Journal of Physics},\n\ttitle = {Detecting topological entanglement entropy in a lattice of quantum harmonic oscillators},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84907317013&doi=10.1088%2f1367-2630%2f16%2f8%2f085011&partnerID=40&md5=8efdb83178b2c09740cc4b3baced1e47},\n\tvolume = {16},\n\tyear = {2014},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84907317013&doi=10.1088%2f1367-2630%2f16%2f8%2f085011&partnerID=40&md5=8efdb83178b2c09740cc4b3baced1e47},\n\tBdsk-Url-2 = {https://doi.org/10.1088/1367-2630/16/8/085011}}\n\n
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\n The Kitaev surface code model is the most studied example of a topologically ordered phase and typically involves four-spin interactions on a two-dimensional surface. A universal signature of this phase is topological entanglement entropy (TEE), but due to low signal to noise, it is extremely difficult to observe in these systems, and one usually resorts to measuring anyonic statistics of excitations or non-local string operators to reveal the order. We describe a continuous-variable analog to the surface code using quantum harmonic oscillators on a two-dimensional lattice, which has the distinctive property of needing only two-body nearest-neighbor interactions for its creation. Though such a model is gapless, it satisfies an area law and the ground state can be simply prepared by measurements on a finitely squeezed and gapped two-dimensional cluster-state without topological order. Asymptotically, the continuous variable surface code TEE grows linearly with the squeezing parameter and a recently discovered non-local quantity, the topological logarithmic negativity, behaves analogously. We also show that the mixed-state generalization of the TEE, the topological mutual information, is robust to some forms of state preparation error and can be detected simply using single-mode quadrature measurements. Finally, we discuss scalable implementation of these methods using optical and circuit-QED technology. © 2014 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.\n
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\n \n\n \n \n \n \n \n \n Clausius entropy for arbitrary bifurcate null surfaces.\n \n \n \n \n\n\n \n Baccetti, V.; and Visser, M.\n\n\n \n\n\n\n Classical and Quantum Gravity, 31(3). 2014.\n \n\n\n\n
\n\n\n\n \n \n \"Clausius link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Baccetti2014,\n\tabstract = {Jacobson\\'s thermodynamic derivation of the Einstein equations was originally applied only to local Rindler horizons. But at least some parts of that construction can usefully be extended to give meaningful results for arbitrary bifurcate null surfaces. As presaged in Jacobson\\'s original article, this more general construction sharply brings into focus the questions: is entropy objectively \\'real\\'? Or is entropy in some sense subjective and observer-dependent? These innocent questions open a Pandora\\'s box of often inconclusive debate. A consensus opinion, though certainly not universally held, seems to be that Clausius entropy (thermodynamic entropy, defined via a Clausius relation ) should be objectively real, but that the ontological status of statistical entropy (Shannon or von Neumann entropy) is much more ambiguous, and much more likely to be observer-dependent. This question is particularly pressing when it comes to understanding Bekenstein entropy (black hole entropy). To perhaps further add to the confusion, we shall argue that even the Clausius entropy can often be observer-dependent. In the current article we shall conclusively demonstrate that one can meaningfully assign a notion of Clausius entropy to arbitrary bifurcate null surfaces - effectively defining a \\'virtual Clausius entropy\\' for arbitrary \\'virtual (local) causal horizons\\'. As an application, we see that we can implement a version of the generalized second law (GSL) for this virtual Clausius entropy. This version of GSL can be related to certain (nonstandard) integral variants of the null energy condition. Because the concepts involved are rather subtle, we take some effort in being careful and explicit in developing our framework. In future work we will apply this construction to generalize Jacobson\\'s derivation of the Einstein equations. {\\copyright} 2014 IOP Publishing Ltd.},\n\tart_number = {035009},\n\tauthor = {Baccetti, V. and Visser, M.},\n\tdate-added = {2019-03-18 11:59:12 +1100},\n\tdate-modified = {2019-03-18 11:59:12 +1100},\n\tdoi = {10.1088/0264-9381/31/3/035009},\n\tjournal = {Classical and Quantum Gravity},\n\tnumber = {3},\n\ttitle = {Clausius entropy for arbitrary bifurcate null surfaces},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84892736873&doi=10.1088%2f0264-9381%2f31%2f3%2f035009&partnerID=40&md5=dcb33f2c44466addae649f7d15109c8a},\n\tvolume = {31},\n\tyear = {2014},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84892736873&doi=10.1088%2f0264-9381%2f31%2f3%2f035009&partnerID=40&md5=dcb33f2c44466addae649f7d15109c8a},\n\tBdsk-Url-2 = {https://doi.org/10.1088/0264-9381/31/3/035009}}\n\n
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\n Jacobsonś thermodynamic derivation of the Einstein equations was originally applied only to local Rindler horizons. But at least some parts of that construction can usefully be extended to give meaningful results for arbitrary bifurcate null surfaces. As presaged in Jacobsonś original article, this more general construction sharply brings into focus the questions: is entropy objectively ŕeal?́ Or is entropy in some sense subjective and observer-dependent? These innocent questions open a Pandoraś box of often inconclusive debate. A consensus opinion, though certainly not universally held, seems to be that Clausius entropy (thermodynamic entropy, defined via a Clausius relation ) should be objectively real, but that the ontological status of statistical entropy (Shannon or von Neumann entropy) is much more ambiguous, and much more likely to be observer-dependent. This question is particularly pressing when it comes to understanding Bekenstein entropy (black hole entropy). To perhaps further add to the confusion, we shall argue that even the Clausius entropy can often be observer-dependent. In the current article we shall conclusively demonstrate that one can meaningfully assign a notion of Clausius entropy to arbitrary bifurcate null surfaces - effectively defining a v́irtual Clausius entropy ́for arbitrary v́irtual (local) causal horizons.́ As an application, we see that we can implement a version of the generalized second law (GSL) for this virtual Clausius entropy. This version of GSL can be related to certain (nonstandard) integral variants of the null energy condition. Because the concepts involved are rather subtle, we take some effort in being careful and explicit in developing our framework. In future work we will apply this construction to generalize Jacobsonś derivation of the Einstein equations. © 2014 IOP Publishing Ltd.\n
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\n \n\n \n \n \n \n \n \n Testing the effects of gravity and motion on quantum entanglement in space-based experiments.\n \n \n \n \n\n\n \n Edward Bruschi, D.; Sabı́n, C.; White, A.; Baccetti, V.; Oi, D.; and Fuentes, I.\n\n\n \n\n\n\n New Journal of Physics, 16. 2014.\n \n\n\n\n
\n\n\n\n \n \n \"Testing link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{EdwardBruschi2014,\n\tabstract = {We propose an experiment to test the effects of gravity and acceleration on quantum entanglement in space-based setups. We show that the entanglement between excitations of two Bose-Einstein condensates is degraded after one of them undergoes a change in the gravitational field strength. This prediction can be tested if the condensates are initially entangled in two separate satellites while being in the same orbit and then one of them moves to a different orbit. We show that the effect is observable in a typical orbital manoeuvre of nanosatellites like CanX4 and CanX5. {\\copyright} 2014 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.},\n\tart_number = {053041},\n\tauthor = {Edward Bruschi, D. and Sab{\\'\\i}n, C. and White, A. and Baccetti, V. and Oi, D.K.L. and Fuentes, I.},\n\tdate-added = {2019-03-18 11:59:12 +1100},\n\tdate-modified = {2019-03-18 11:59:12 +1100},\n\tdoi = {10.1088/1367-2630/16/5/053041},\n\tjournal = {New Journal of Physics},\n\ttitle = {Testing the effects of gravity and motion on quantum entanglement in space-based experiments},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84901709611&doi=10.1088%2f1367-2630%2f16%2f5%2f053041&partnerID=40&md5=07bf5056a452a398cb80d5a885150502},\n\tvolume = {16},\n\tyear = {2014},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84901709611&doi=10.1088%2f1367-2630%2f16%2f5%2f053041&partnerID=40&md5=07bf5056a452a398cb80d5a885150502},\n\tBdsk-Url-2 = {https://doi.org/10.1088/1367-2630/16/5/053041}}\n\n
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\n We propose an experiment to test the effects of gravity and acceleration on quantum entanglement in space-based setups. We show that the entanglement between excitations of two Bose-Einstein condensates is degraded after one of them undergoes a change in the gravitational field strength. This prediction can be tested if the condensates are initially entangled in two separate satellites while being in the same orbit and then one of them moves to a different orbit. We show that the effect is observable in a typical orbital manoeuvre of nanosatellites like CanX4 and CanX5. © 2014 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.\n
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\n \n\n \n \n \n \n \n \n Erratum: Three-dimensional light-matter interface for collective spin squeezing in atomic ensembles (Physical Review A - Atomic, Molecular, and Optical Physics (2014) 89 (033850)).\n \n \n \n \n\n\n \n Baragiola, B.; Norris, L.; Montaño, E.; Mickelson, P.; Jessen, P.; and Deutsch, I.\n\n\n \n\n\n\n Physical Review A - Atomic, Molecular, and Optical Physics, 89(4). 2014.\n \n\n\n\n
\n\n\n\n \n \n \"Erratum: link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Baragiola2014,\n\tart_number = {049901},\n\tauthor = {Baragiola, B.Q. and Norris, L.M. and Monta{\\~n}o, E. and Mickelson, P.G. and Jessen, P.S. and Deutsch, I.H.},\n\tdoi = {10.1103/PhysRevA.89.049901},\n\tjournal = {Physical Review A - Atomic, Molecular, and Optical Physics},\n\tnumber = {4},\n\ttitle = {Erratum: Three-dimensional light-matter interface for collective spin squeezing in atomic ensembles (Physical Review A - Atomic, Molecular, and Optical Physics (2014) 89 (033850))},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84898851055&doi=10.1103%2fPhysRevA.89.049901&partnerID=40&md5=96997f19e81c91a176164a84d564b4df},\n\tvolume = {89},\n\tyear = {2014},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84898851055&doi=10.1103%2fPhysRevA.89.049901&partnerID=40&md5=96997f19e81c91a176164a84d564b4df},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.89.049901}}\n\n
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\n \n\n \n \n \n \n \n \n Three-dimensional light-matter interface for collective spin squeezing in atomic ensembles.\n \n \n \n \n\n\n \n Baragiola, B.; Norris, L.; Montaño, E.; Mickelson, P.; Jessen, P.; and Deutsch, I.\n\n\n \n\n\n\n Physical Review A - Atomic, Molecular, and Optical Physics, 89(3). 2014.\n \n\n\n\n
\n\n\n\n \n \n \"Three-dimensional link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Baragiola2014,\n\tabstract = {We study the three-dimensional nature of the quantum interface between an ensemble of cold, trapped atomic spins and a paraxial laser beam, coupled through a dispersive interaction. To achieve strong entanglement between the collective atomic spin and the photons, one must match the spatial mode of the collective radiation of the ensemble with the mode of the laser beam while minimizing the effects of decoherence due to optical pumping. For ensembles coupling to a probe field that varies over the extent of the cloud, the set of atoms that indistinguishably radiates into a desired mode of the field defines an inhomogeneous spin wave. Strong coupling of a spin wave to the probe mode is not characterized by a single parameter, the optical density, but by a collection of different effective atom numbers that characterize the coherence and decoherence of the system. To model the dynamics of the system, we develop a full stochastic master equation, including coherent collective scattering into paraxial modes, decoherence by local inhomogeneous diffuse scattering, and backaction due to continuous measurement of the light entangled with the spin waves. This formalism is used to study the squeezing of a spin wave via continuous quantum nondemolition measurement. We find that the greatest squeezing occurs in parameter regimes where spatial inhomogeneities are significant, far from the limit in which the interface is well approximated by a one-dimensional, homogeneous model. {\\copyright} 2014 American Physical Society.},\n\tart_number = {033850},\n\tauthor = {Baragiola, B.Q. and Norris, L.M. and Monta{\\~n}o, E. and Mickelson, P.G. and Jessen, P.S. and Deutsch, I.H.},\n\tdoi = {10.1103/PhysRevA.89.033850},\n\tjournal = {Physical Review A - Atomic, Molecular, and Optical Physics},\n\tnumber = {3},\n\ttitle = {Three-dimensional light-matter interface for collective spin squeezing in atomic ensembles},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84898060379&doi=10.1103%2fPhysRevA.89.033850&partnerID=40&md5=a788264f9b3d2994df03e8659bfac70f},\n\tvolume = {89},\n\tyear = {2014},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84898060379&doi=10.1103%2fPhysRevA.89.033850&partnerID=40&md5=a788264f9b3d2994df03e8659bfac70f},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.89.033850}}\n\n
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\n We study the three-dimensional nature of the quantum interface between an ensemble of cold, trapped atomic spins and a paraxial laser beam, coupled through a dispersive interaction. To achieve strong entanglement between the collective atomic spin and the photons, one must match the spatial mode of the collective radiation of the ensemble with the mode of the laser beam while minimizing the effects of decoherence due to optical pumping. For ensembles coupling to a probe field that varies over the extent of the cloud, the set of atoms that indistinguishably radiates into a desired mode of the field defines an inhomogeneous spin wave. Strong coupling of a spin wave to the probe mode is not characterized by a single parameter, the optical density, but by a collection of different effective atom numbers that characterize the coherence and decoherence of the system. To model the dynamics of the system, we develop a full stochastic master equation, including coherent collective scattering into paraxial modes, decoherence by local inhomogeneous diffuse scattering, and backaction due to continuous measurement of the light entangled with the spin waves. This formalism is used to study the squeezing of a spin wave via continuous quantum nondemolition measurement. We find that the greatest squeezing occurs in parameter regimes where spatial inhomogeneities are significant, far from the limit in which the interface is well approximated by a one-dimensional, homogeneous model. © 2014 American Physical Society.\n
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\n \n\n \n \n \n \n \n \n Quantum nondemolition detection of a propagating microwave photon.\n \n \n \n \n\n\n \n Sathyamoorthy, S.; Tornberg, L.; Kockum, A.; Baragiola, B.; Combes, J.; Wilson, C.; Stace, T.; and Johansson, G.\n\n\n \n\n\n\n Physical Review Letters, 112(9). 2014.\n \n\n\n\n
\n\n\n\n \n \n \"Quantum link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Sathyamoorthy2014,\n\tabstract = {The ability to nondestructively detect the presence of a single, traveling photon has been a long-standing goal in optics, with applications in quantum information and measurement. Realizing such a detector is complicated by the fact that photon-photon interactions are typically very weak. At microwave frequencies, very strong effective photon-photon interactions in a waveguide have recently been demonstrated. Here we show how this type of interaction can be used to realize a quantum nondemolition measurement of a single propagating microwave photon. The scheme we propose uses a chain of solid-state three-level systems (transmons) cascaded through circulators which suppress photon backscattering. Our theoretical analysis shows that microwave-photon detection with fidelity around 90% can be realized with existing technologies. {\\copyright} 2014 American Physical Society.},\n\tart_number = {093601},\n\tauthor = {Sathyamoorthy, S.R. and Tornberg, L. and Kockum, A.F. and Baragiola, B.Q. and Combes, J. and Wilson, C.M. and Stace, T.M. and Johansson, G.},\n\tdoi = {10.1103/PhysRevLett.112.093601},\n\tjournal = {Physical Review Letters},\n\tnumber = {9},\n\ttitle = {Quantum nondemolition detection of a propagating microwave photon},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84897681876&doi=10.1103%2fPhysRevLett.112.093601&partnerID=40&md5=f622f40077962760c08b0511b5a08d5c},\n\tvolume = {112},\n\tyear = {2014},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84897681876&doi=10.1103%2fPhysRevLett.112.093601&partnerID=40&md5=f622f40077962760c08b0511b5a08d5c},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevLett.112.093601}}\n\n
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\n The ability to nondestructively detect the presence of a single, traveling photon has been a long-standing goal in optics, with applications in quantum information and measurement. Realizing such a detector is complicated by the fact that photon-photon interactions are typically very weak. At microwave frequencies, very strong effective photon-photon interactions in a waveguide have recently been demonstrated. Here we show how this type of interaction can be used to realize a quantum nondemolition measurement of a single propagating microwave photon. The scheme we propose uses a chain of solid-state three-level systems (transmons) cascaded through circulators which suppress photon backscattering. Our theoretical analysis shows that microwave-photon detection with fidelity around 90% can be realized with existing technologies. © 2014 American Physical Society.\n
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\n  \n 2013\n \n \n (7)\n \n \n
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\n \n\n \n \n \n \n \n \n Ultra-large-scale continuous-variable cluster states multiplexed in the time domain.\n \n \n \n \n\n\n \n Yokoyama, S.; Ukai, R.; Armstrong, S.; Sornphiphatphong, C.; Kaji, T.; Suzuki, S.; Yoshikawa, J.; Yonezawa, H.; Menicucci, N.; and Furusawa, A.\n\n\n \n\n\n\n Nature Photonics, 7(12). 2013.\n \n\n\n\n
\n\n\n\n \n \n \"Ultra-large-scale link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Yokoyama2013982,\n\tabstract = {Quantum computers promise ultrafast performance for certain tasks. Experimentally appealing, measurement-based quantum computation requires an entangled resource called a cluster state, with long computations requiring large cluster states. Previously, the largest cluster state consisted of eight photonic qubits or light modes, and the largest multipartite entangled state of any sort involved 14 trapped ions. These implementations involve quantum entities separated in space and, in general, each experimental apparatus is used only once. Here, we circumvent this inherent inefficiency by multiplexing light modes in the time domain. We deterministically generate and fully characterize a continuous-variable cluster state containing more than 10,000 entangled modes. This is, by three orders of magnitude, the largest entangled state created to date. The entangled modes are individually addressable wave packets of light in two beams. Furthermore, we present an efficient scheme for measurement-based quantum computation on this cluster state based on sequential applications of quantum teleportation. {\\copyright} 2013 Macmillan Publishers Limited. All rights reserved.},\n\tart_number = {982-986},\n\tauthor = {Yokoyama, S. and Ukai, R. and Armstrong, S.C. and Sornphiphatphong, C. and Kaji, T. and Suzuki, S. and Yoshikawa, J.-I. and Yonezawa, H. and Menicucci, N.C. and Furusawa, A.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-19 16:35:29 +1100},\n\tdoi = {10.1038/nphoton.2013.287},\n\tjournal = {Nature Photonics},\n\tnumber = {12},\n\ttitle = {Ultra-large-scale continuous-variable cluster states multiplexed in the time domain},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84889092785&doi=10.1038%2fnphoton.2013.287&partnerID=40&md5=d72f6eff748bb30f5b327d49c0268c9f},\n\tvolume = {7},\n\tyear = {2013},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84889092785&doi=10.1038%2fnphoton.2013.287&partnerID=40&md5=d72f6eff748bb30f5b327d49c0268c9f},\n\tBdsk-Url-2 = {https://doi.org/10.1038/nphoton.2013.287}}\n\n
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\n Quantum computers promise ultrafast performance for certain tasks. Experimentally appealing, measurement-based quantum computation requires an entangled resource called a cluster state, with long computations requiring large cluster states. Previously, the largest cluster state consisted of eight photonic qubits or light modes, and the largest multipartite entangled state of any sort involved 14 trapped ions. These implementations involve quantum entities separated in space and, in general, each experimental apparatus is used only once. Here, we circumvent this inherent inefficiency by multiplexing light modes in the time domain. We deterministically generate and fully characterize a continuous-variable cluster state containing more than 10,000 entangled modes. This is, by three orders of magnitude, the largest entangled state created to date. The entangled modes are individually addressable wave packets of light in two beams. Furthermore, we present an efficient scheme for measurement-based quantum computation on this cluster state based on sequential applications of quantum teleportation. © 2013 Macmillan Publishers Limited. All rights reserved.\n
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\n \n\n \n \n \n \n \n \n Fault-tolerant measurement-based quantum computing with continuous-variable cluster states.\n \n \n \n \n\n\n \n Menicucci, N.\n\n\n \n\n\n\n Physical Review Letters, 112(12). 2013.\n \n\n\n\n
\n\n\n\n \n \n \"Fault-tolerant link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Menicucci2013,\n\tabstract = {A long-standing open question about Gaussian continuous-variable cluster states is whether they enable fault-tolerant measurement-based quantum computation. The answer is yes. Initial squeezing in the cluster above a threshold value of 20.5 dB ensures that errors from finite squeezing acting on encoded qubits are below the fault-tolerance threshold of known qubit-based error-correcting codes. By concatenating with one of these codes and using ancilla-based error correction, fault-tolerant measurement-based quantum computation of theoretically indefinite length is possible with finitely squeezed cluster states. {\\copyright} 2014 American Physical Society.},\n\tart_number = {120504},\n\tauthor = {Menicucci, N.C.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1103/PhysRevLett.112.120504},\n\tjournal = {Physical Review Letters},\n\tnumber = {12},\n\ttitle = {Fault-tolerant measurement-based quantum computing with continuous-variable cluster states},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84897388995&doi=10.1103%2fPhysRevLett.112.120504&partnerID=40&md5=024f585c84a9ef26e179e7d8636d1dd8},\n\tvolume = {112},\n\tyear = {2013},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84897388995&doi=10.1103%2fPhysRevLett.112.120504&partnerID=40&md5=024f585c84a9ef26e179e7d8636d1dd8},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevLett.112.120504}}\n\n
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\n A long-standing open question about Gaussian continuous-variable cluster states is whether they enable fault-tolerant measurement-based quantum computation. The answer is yes. Initial squeezing in the cluster above a threshold value of 20.5 dB ensures that errors from finite squeezing acting on encoded qubits are below the fault-tolerance threshold of known qubit-based error-correcting codes. By concatenating with one of these codes and using ancilla-based error correction, fault-tolerant measurement-based quantum computation of theoretically indefinite length is possible with finitely squeezed cluster states. © 2014 American Physical Society.\n
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\n \n\n \n \n \n \n \n \n Experimental realization of multipartite entanglement of 60 modes of a quantum optical frequency comb.\n \n \n \n \n\n\n \n Chen, M.; Menicucci, N.; and Pfister, O.\n\n\n \n\n\n\n Physical Review Letters, 112(12). 2013.\n \n\n\n\n
\n\n\n\n \n \n \"Experimental link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Chen2013,\n\tabstract = {We report the experimental realization and characterization of one 60-mode copy and of two 30-mode copies of a dual-rail quantum-wire cluster state in the quantum optical frequency comb of a bimodally pumped optical parametric oscillator. This is the largest entangled system ever created whose subsystems are all available simultaneously. The entanglement proceeds from the coherent concatenation of a multitude of Einstein, Podolsky, and Rosen pairs by a single beam splitter, a procedure which is also a building block for the realization of hypercubic-lattice cluster states for universal quantum computing. {\\copyright} 2014 American Physical Society.},\n\tart_number = {120505},\n\tauthor = {Chen, M. and Menicucci, N.C. and Pfister, O.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1103/PhysRevLett.112.120505},\n\tjournal = {Physical Review Letters},\n\tnumber = {12},\n\ttitle = {Experimental realization of multipartite entanglement of 60 modes of a quantum optical frequency comb},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84897430234&doi=10.1103%2fPhysRevLett.112.120505&partnerID=40&md5=05a432b6658a21156978739b8e784409},\n\tvolume = {112},\n\tyear = {2013},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84897430234&doi=10.1103%2fPhysRevLett.112.120505&partnerID=40&md5=05a432b6658a21156978739b8e784409},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevLett.112.120505}}\n\n
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\n We report the experimental realization and characterization of one 60-mode copy and of two 30-mode copies of a dual-rail quantum-wire cluster state in the quantum optical frequency comb of a bimodally pumped optical parametric oscillator. This is the largest entangled system ever created whose subsystems are all available simultaneously. The entanglement proceeds from the coherent concatenation of a multitude of Einstein, Podolsky, and Rosen pairs by a single beam splitter, a procedure which is also a building block for the realization of hypercubic-lattice cluster states for universal quantum computing. © 2014 American Physical Society.\n
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\n \n\n \n \n \n \n \n \n Experimental generation of 2000-mode entangled graph states.\n \n \n \n \n\n\n \n Yokoyama, S.; Sornphiphatphong, C.; Kaji, T.; Ukai, R.; Armstrong, S.; Suzuki, S.; Yoshikawa, J.; Menicucci, N.; and Furusawa, A.\n\n\n \n\n\n\n 2013.\n \n\n\n\n
\n\n\n\n \n \n \"Experimental link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@conference{Yokoyama2013,\n\tabstract = {Quantum entanglement is not only the fundamental feature of quantum physics, it is the key ingredient in quantum information protocols. In order to achieve large-scale quantum information processing, large-scale multipartite entangled states are needed. To date, entangled states containing around 10 modes have been generated using atoms, ions, photons, and optical continuous-variable (CV) schemes. In the vast majority of CV experiments, each optical mode is distinguished from the other modes by its spatial location. {\\copyright} 2013 IEEE.},\n\tart_number = {6801669},\n\tauthor = {Yokoyama, S. and Sornphiphatphong, C. and Kaji, T. and Ukai, R. and Armstrong, S.C. and Suzuki, S. and Yoshikawa, J. and Menicucci, N.C. and Furusawa, A.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1109/CLEOE-IQEC.2013.6801669},\n\tjournal = {2013 Conference on Lasers and Electro-Optics Europe and International Quantum Electronics Conference, CLEO/Europe-IQEC 2013},\n\ttitle = {Experimental generation of 2000-mode entangled graph states},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84900334796&doi=10.1109%2fCLEOE-IQEC.2013.6801669&partnerID=40&md5=0562a0d2e38c7d3766ddf223c15fb654},\n\tyear = {2013},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84900334796&doi=10.1109%2fCLEOE-IQEC.2013.6801669&partnerID=40&md5=0562a0d2e38c7d3766ddf223c15fb654},\n\tBdsk-Url-2 = {https://doi.org/10.1109/CLEOE-IQEC.2013.6801669}}\n\n
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\n Quantum entanglement is not only the fundamental feature of quantum physics, it is the key ingredient in quantum information protocols. In order to achieve large-scale quantum information processing, large-scale multipartite entangled states are needed. To date, entangled states containing around 10 modes have been generated using atoms, ions, photons, and optical continuous-variable (CV) schemes. In the vast majority of CV experiments, each optical mode is distinguished from the other modes by its spatial location. © 2013 IEEE.\n
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\n \n\n \n \n \n \n \n \n Detectors for probing relativistic quantum physics beyond perturbation theory.\n \n \n \n \n\n\n \n Brown, E.; Martı́n-Martı́nez, E.; Menicucci, N.; and Mann, R.\n\n\n \n\n\n\n Physical Review D - Particles, Fields, Gravitation and Cosmology, 87(8). 2013.\n \n\n\n\n
\n\n\n\n \n \n \"Detectors link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Brown2013,\n\tabstract = {We develop a general formalism for a nonperturbative treatment of harmonic-oscillator particle detectors in relativistic quantum field theory using continuous-variable techniques. By means of this we forgo perturbation theory altogether and reduce the complete dynamics to a readily solvable set of first-order, linear differential equations. The formalism applies unchanged to a wide variety of physical setups, including arbitrary detector trajectories, any number of detectors, arbitrary time-dependent quadratic couplings, arbitrary Gaussian initial states, and a variety of background spacetimes. As a first set of concrete results, we prove nonperturbatively - and without invoking Bogoliubov transformations - that an accelerated detector in a cavity evolves to a state that is very nearly thermal with a temperature proportional to its acceleration, allowing us to discuss the universality of the Unruh effect. Additionally we quantitatively analyze the problems of considering single-mode approximations in cavity field theory and show the emergence of causal behavior when we include a sufficiently large number of field modes in the analysis. Finally, we analyze how the harmonic particle detector can harvest entanglement from the vacuum. We also study the effect of noise in time-dependent problems introduced by suddenly switching on the interaction versus ramping it up slowly (adiabatic activation). {\\copyright} 2013 American Physical Society.},\n\tart_number = {084062},\n\tauthor = {Brown, E.G. and Mart{\\'\\i}n-Mart{\\'\\i}nez, E. and Menicucci, N.C. and Mann, R.B.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1103/PhysRevD.87.084062},\n\tjournal = {Physical Review D - Particles, Fields, Gravitation and Cosmology},\n\tnumber = {8},\n\ttitle = {Detectors for probing relativistic quantum physics beyond perturbation theory},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84877114824&doi=10.1103%2fPhysRevD.87.084062&partnerID=40&md5=cfb9bf294896ea2afdb0f01c2c854987},\n\tvolume = {87},\n\tyear = {2013},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84877114824&doi=10.1103%2fPhysRevD.87.084062&partnerID=40&md5=cfb9bf294896ea2afdb0f01c2c854987},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevD.87.084062}}\n\n
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\n We develop a general formalism for a nonperturbative treatment of harmonic-oscillator particle detectors in relativistic quantum field theory using continuous-variable techniques. By means of this we forgo perturbation theory altogether and reduce the complete dynamics to a readily solvable set of first-order, linear differential equations. The formalism applies unchanged to a wide variety of physical setups, including arbitrary detector trajectories, any number of detectors, arbitrary time-dependent quadratic couplings, arbitrary Gaussian initial states, and a variety of background spacetimes. As a first set of concrete results, we prove nonperturbatively - and without invoking Bogoliubov transformations - that an accelerated detector in a cavity evolves to a state that is very nearly thermal with a temperature proportional to its acceleration, allowing us to discuss the universality of the Unruh effect. Additionally we quantitatively analyze the problems of considering single-mode approximations in cavity field theory and show the emergence of causal behavior when we include a sufficiently large number of field modes in the analysis. Finally, we analyze how the harmonic particle detector can harvest entanglement from the vacuum. We also study the effect of noise in time-dependent problems introduced by suddenly switching on the interaction versus ramping it up slowly (adiabatic activation). © 2013 American Physical Society.\n
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\n \n\n \n \n \n \n \n \n Infinite Shannon entropy.\n \n \n \n \n\n\n \n Baccetti, V.; and Visser, M.\n\n\n \n\n\n\n Journal of Statistical Mechanics: Theory and Experiment, 2013(4). 2013.\n \n\n\n\n
\n\n\n\n \n \n \"Infinite link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Baccetti2013,\n\tabstract = {Even if a probability distribution is properly normalizable, its associated Shannon (or von Neumann) entropy can easily be infinite. We carefully analyze conditions under which this phenomenon can occur. Roughly speaking, this happens when arbitrarily small amounts of probability are dispersed into an infinite number of states; we shall quantify this observation and make it precise. We develop several particularly simple, elementary, and useful bounds, and also provide some asymptotic estimates, leading to necessary and sufficient conditions for the occurrence of infinite Shannon entropy. We go to some effort to keep technical computations as simple and conceptually clear as possible. In particular, we shall see that large entropies cannot be localized in state space; large entropies can only be supported on an exponentially large number of states. We are for the time being interested in single-channel Shannon entropy in the information theoretic sense, not entropy in a stochastic field theory or quantum field theory defined over some configuration space, on the grounds that this simple problem is a necessary precursor to understanding infinite entropy in a field theoretic context. {\\copyright} 2013 IOP Publishing Ltd and SISSA Medialab srl.},\n\tart_number = {P04010},\n\tauthor = {Baccetti, V. and Visser, M.},\n\tdate-added = {2019-03-18 11:59:12 +1100},\n\tdate-modified = {2019-03-18 11:59:12 +1100},\n\tdoi = {10.1088/1742-5468/2013/04/P04010},\n\tjournal = {Journal of Statistical Mechanics: Theory and Experiment},\n\tnumber = {4},\n\ttitle = {Infinite Shannon entropy},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84876929831&doi=10.1088%2f1742-5468%2f2013%2f04%2fP04010&partnerID=40&md5=5fd2a0b6546578420c4320ab9e4ff74f},\n\tvolume = {2013},\n\tyear = {2013},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84876929831&doi=10.1088%2f1742-5468%2f2013%2f04%2fP04010&partnerID=40&md5=5fd2a0b6546578420c4320ab9e4ff74f},\n\tBdsk-Url-2 = {https://doi.org/10.1088/1742-5468/2013/04/P04010}}\n\n
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\n Even if a probability distribution is properly normalizable, its associated Shannon (or von Neumann) entropy can easily be infinite. We carefully analyze conditions under which this phenomenon can occur. Roughly speaking, this happens when arbitrarily small amounts of probability are dispersed into an infinite number of states; we shall quantify this observation and make it precise. We develop several particularly simple, elementary, and useful bounds, and also provide some asymptotic estimates, leading to necessary and sufficient conditions for the occurrence of infinite Shannon entropy. We go to some effort to keep technical computations as simple and conceptually clear as possible. In particular, we shall see that large entropies cannot be localized in state space; large entropies can only be supported on an exponentially large number of states. We are for the time being interested in single-channel Shannon entropy in the information theoretic sense, not entropy in a stochastic field theory or quantum field theory defined over some configuration space, on the grounds that this simple problem is a necessary precursor to understanding infinite entropy in a field theoretic context. © 2013 IOP Publishing Ltd and SISSA Medialab srl.\n
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\n \n\n \n \n \n \n \n \n Massive gravity from bimetric gravity.\n \n \n \n \n\n\n \n Baccetti, V.; Martı́n-Moruno, P.; and Visser, M.\n\n\n \n\n\n\n Classical and Quantum Gravity, 30(1). 2013.\n \n\n\n\n
\n\n\n\n \n \n \"Massive link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Baccetti2013,\n\tabstract = {We discuss the subtle relationship between massive gravity and bimetric gravity, focusing particularly on the manner in which massive gravity may be viewed as a suitable limit of bimetric gravity. The limiting procedure is more delicate than currently appreciated. Specifically, this limiting procedure should not unnecessarily constrain the background metric, which must be externally specified by the theory of massive gravity itself. The fact that in bimetric theories one always has two sets of metric equations of motion continues to have an effect even in the massive gravity limit, leading to additional constraints besides the one set of equations of motion naively expected. Thus, since solutions of bimetric gravity in the limit of vanishing kinetic term are also solutions of massive gravity, but the contrary statement is not necessarily true, there is no complete continuity in the parameter space of the theory. In particular, we study the massive cosmological solutions which are continuous in the parameter space, showing that many interesting cosmologies belong to this class. {\\copyright} 2013 IOP Publishing Ltd.},\n\tart_number = {015004},\n\tauthor = {Baccetti, V. and Mart{\\'\\i}n-Moruno, P. and Visser, M.},\n\tdate-added = {2019-03-18 11:59:12 +1100},\n\tdate-modified = {2019-03-18 11:59:12 +1100},\n\tdoi = {10.1088/0264-9381/30/1/015004},\n\tjournal = {Classical and Quantum Gravity},\n\tnumber = {1},\n\ttitle = {Massive gravity from bimetric gravity},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84871432749&doi=10.1088%2f0264-9381%2f30%2f1%2f015004&partnerID=40&md5=b18bd105182c32fce48e61054d82fc90},\n\tvolume = {30},\n\tyear = {2013},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84871432749&doi=10.1088%2f0264-9381%2f30%2f1%2f015004&partnerID=40&md5=b18bd105182c32fce48e61054d82fc90},\n\tBdsk-Url-2 = {https://doi.org/10.1088/0264-9381/30/1/015004}}\n\n
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\n\n\n
\n We discuss the subtle relationship between massive gravity and bimetric gravity, focusing particularly on the manner in which massive gravity may be viewed as a suitable limit of bimetric gravity. The limiting procedure is more delicate than currently appreciated. Specifically, this limiting procedure should not unnecessarily constrain the background metric, which must be externally specified by the theory of massive gravity itself. The fact that in bimetric theories one always has two sets of metric equations of motion continues to have an effect even in the massive gravity limit, leading to additional constraints besides the one set of equations of motion naively expected. Thus, since solutions of bimetric gravity in the limit of vanishing kinetic term are also solutions of massive gravity, but the contrary statement is not necessarily true, there is no complete continuity in the parameter space of the theory. In particular, we study the massive cosmological solutions which are continuous in the parameter space, showing that many interesting cosmologies belong to this class. © 2013 IOP Publishing Ltd.\n
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\n  \n 2012\n \n \n (6)\n \n \n
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\n \n\n \n \n \n \n \n \n Fundamental quantum optics experiments conceivable with satellites - Reaching relativistic distances and velocities.\n \n \n \n \n\n\n \n Rideout, D.; Jennewein, T.; Amelino-Camelia, G.; Demarie, T.; Higgins, B.; Kempf, A.; Kent, A.; Laflamme, R.; Ma, X.; Mann, R.; Martı́n-Martı́nez, E.; Menicucci, N.; Moffat, J.; Simon, C.; Sorkin, R.; Smolin, L.; and Terno, D.\n\n\n \n\n\n\n Classical and Quantum Gravity, 29(22). 2012.\n \n\n\n\n
\n\n\n\n \n \n \"Fundamental link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n  \n \n 1 download\n \n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Rideout2012,\n\tabstract = {Physical theories are developed to describe phenomena in particular regimes, and generally are valid only within a limited range of scales. For example, general relativity provides an effective description of the Universe at large length scales, and has been tested from the cosmic scale down to distances as small as 10m (Dimopoulos 2007 Phys. Rev. Lett. 98 111102; 2008 Phys. Rev. D 78 042003). In contrast, quantum theory provides an effective description of physics at small length scales. Direct tests of quantum theory have been performed at the smallest probeable scales at the Large Hadron Collider, 10 20 m, up to that of hundreds of kilometres (Ursin et al 2007 Nature Phys. 3 481-6). Yet, such tests fall short of the scales required to investigate potentially significant physics that arises at the intersection of quantum and relativistic regimes. We propose to push direct tests of quantum theory to larger and larger length scales, approaching that of the radius of curvature of spacetime, where we begin to probe the interaction between gravity and quantum phenomena. In particular, we review a wide variety of potential tests of fundamental physics that are conceivable with artificial satellites in Earth orbit and elsewhere in the solar system, and attempt to sketch the magnitudes of potentially observable effects. The tests have the potential to determine the applicability of quantum theory at larger length scales, eliminate various alternative physical theories, and place bounds on phenomenological models motivated by ideas about spacetime microstructure from quantum gravity. From a more pragmatic perspective, as quantum communication technologies such as quantum key distribution advance into space towards large distances, some of the fundamental physical effects discussed here may need to be taken into account to make such schemes viable. {\\copyright} 2012 IOP Publishing Ltd.},\n\tart_number = {224011},\n\tauthor = {Rideout, D. and Jennewein, T. and Amelino-Camelia, G. and Demarie, T.F. and Higgins, B.L. and Kempf, A. and Kent, A. and Laflamme, R. and Ma, X. and Mann, R.B. and Mart{\\'\\i}n-Mart{\\'\\i}nez, E. and Menicucci, N.C. and Moffat, J. and Simon, C. and Sorkin, R. and Smolin, L. and Terno, D.R.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1088/0264-9381/29/22/224011},\n\tjournal = {Classical and Quantum Gravity},\n\tnumber = {22},\n\ttitle = {Fundamental quantum optics experiments conceivable with satellites - Reaching relativistic distances and velocities},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84867716963&doi=10.1088%2f0264-9381%2f29%2f22%2f224011&partnerID=40&md5=f23f4df38885aa0d95c9a0a663637c74},\n\tvolume = {29},\n\tyear = {2012},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84867716963&doi=10.1088%2f0264-9381%2f29%2f22%2f224011&partnerID=40&md5=f23f4df38885aa0d95c9a0a663637c74},\n\tBdsk-Url-2 = {https://doi.org/10.1088/0264-9381/29/22/224011}}\n\n
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\n Physical theories are developed to describe phenomena in particular regimes, and generally are valid only within a limited range of scales. For example, general relativity provides an effective description of the Universe at large length scales, and has been tested from the cosmic scale down to distances as small as 10m (Dimopoulos 2007 Phys. Rev. Lett. 98 111102; 2008 Phys. Rev. D 78 042003). In contrast, quantum theory provides an effective description of physics at small length scales. Direct tests of quantum theory have been performed at the smallest probeable scales at the Large Hadron Collider, 10 20 m, up to that of hundreds of kilometres (Ursin et al 2007 Nature Phys. 3 481-6). Yet, such tests fall short of the scales required to investigate potentially significant physics that arises at the intersection of quantum and relativistic regimes. We propose to push direct tests of quantum theory to larger and larger length scales, approaching that of the radius of curvature of spacetime, where we begin to probe the interaction between gravity and quantum phenomena. In particular, we review a wide variety of potential tests of fundamental physics that are conceivable with artificial satellites in Earth orbit and elsewhere in the solar system, and attempt to sketch the magnitudes of potentially observable effects. The tests have the potential to determine the applicability of quantum theory at larger length scales, eliminate various alternative physical theories, and place bounds on phenomenological models motivated by ideas about spacetime microstructure from quantum gravity. From a more pragmatic perspective, as quantum communication technologies such as quantum key distribution advance into space towards large distances, some of the fundamental physical effects discussed here may need to be taken into account to make such schemes viable. © 2012 IOP Publishing Ltd.\n
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\n \n\n \n \n \n \n \n \n Gordon and Kerr-Schild ansätze in massive and bimetric gravity.\n \n \n \n \n\n\n \n Baccetti, V.; Martin-Moruno, P.; and Visser, M.\n\n\n \n\n\n\n Journal of High Energy Physics, 2012(8). 2012.\n \n\n\n\n
\n\n\n\n \n \n \"Gordon link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Baccetti2012,\n\tabstract = {We develop the "generalized Gordon ansatz" for the ghost-free versions of both massive and bimetric gravity, an ansatz which is general enough to include almost all spacetimes commonly considered to be physically interesting, and restricted enough to greatly simplify calculations. The ansatz allows explicit calculation of the matrix square root γ = √g -lf appearing as a central feature of the ghost-free analysis. In particular, this ansatz automatically allows us to write the effective stress-energy tensor as that corresponding to a perfect fluid. A qualitatively similar "generalized Kerr-Schild ansatz" can also be easily considered, now leading to an effective stress-energy tensor that corresponds to a null fluid. Cosmological implications are considered, as are consequences for black hole physics. Finally we have a few words to say concerning the null energy condition in the framework provided by these ans{\\"a}tze. {\\copyright} 2012 SISSA.},\n\tart_number = {108},\n\tauthor = {Baccetti, V. and Martin-Moruno, P. and Visser, M.},\n\tdate-added = {2019-03-18 11:59:12 +1100},\n\tdate-modified = {2019-03-18 11:59:12 +1100},\n\tdoi = {10.1007/JHEP08(2012)108},\n\tjournal = {Journal of High Energy Physics},\n\tnumber = {8},\n\ttitle = {Gordon and Kerr-Schild ans{\\"a}tze in massive and bimetric gravity},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84865734803&doi=10.1007%2fJHEP08%282012%29108&partnerID=40&md5=8b1bc0f8743ed064fd2c239ede336470},\n\tvolume = {2012},\n\tyear = {2012},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84865734803&doi=10.1007%2fJHEP08%282012%29108&partnerID=40&md5=8b1bc0f8743ed064fd2c239ede336470},\n\tBdsk-Url-2 = {https://doi.org/10.1007/JHEP08(2012)108}}\n\n
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\n We develop the \"generalized Gordon ansatz\" for the ghost-free versions of both massive and bimetric gravity, an ansatz which is general enough to include almost all spacetimes commonly considered to be physically interesting, and restricted enough to greatly simplify calculations. The ansatz allows explicit calculation of the matrix square root γ = √g -lf appearing as a central feature of the ghost-free analysis. In particular, this ansatz automatically allows us to write the effective stress-energy tensor as that corresponding to a perfect fluid. A qualitatively similar \"generalized Kerr-Schild ansatz\" can also be easily considered, now leading to an effective stress-energy tensor that corresponds to a null fluid. Cosmological implications are considered, as are consequences for black hole physics. Finally we have a few words to say concerning the null energy condition in the framework provided by these ansätze. © 2012 SISSA.\n
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\n \n\n \n \n \n \n \n \n Inertial frames without the relativity principle.\n \n \n \n \n\n\n \n Baccetti, V.; Tate, K.; and Visser, M.\n\n\n \n\n\n\n Journal of High Energy Physics, 2012(5). 2012.\n \n\n\n\n
\n\n\n\n \n \n \"Inertial link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{Baccetti2012,\n\tabstract = {Ever since the work of von Ignatowsky circa 1910 it has been known (if not always widely appreciated) that the relativity principle, combined with the basic and fundamental physical assumptions of locality, linearity, and isotropy, leads almost uniquely to either the Lorentz transformations of special relativity or to Galileo\\'s transformations of classical Newtonian mechanics. Consequently, if one wishes (for whatever reason) to entertain the possibility of Lorentz symmetry breaking within the context of the class of local physical theories, then it seems likely that one will have to abandon (or at the very least grossly modify) the relativity principle. Working within the framework of local physics, we reassess the notion of spacetime transformations between inertial frames in the absence of the relativity principle, arguing that significant and nontrivial physics can still be extracted as long as the transformations are at least linear. An interesting technical aspect of the analysis is that the transformations now form a groupoid/pseudo-group - it is this technical point that permits one to evade the von Ignatowsky argument. Even in the absence of a relativity principle we can (assuming locality and linearity) nevertheless deduce clear and compelling rules for the transformation of space and time, rules for the composition of 3-velocities, and rules for the transformation of energy and momentum. Within this framework, the energy-momentum transformations are in general affine, but may be chosen to be linear, with the 4-component vector P = (E,-p T ) transforming as a row vector, while the 4-component vector of space-time position X = (t, x T ) T transforms as a column vector. As part of the analysis we identify two particularly elegant and physically compelling models implementing "minimalist" violations of Lorentz invariance - in the first of these minimalist models all Lorentz violations are confined to carefully delineated particle physics sub-sectors, while the second minimalist Lorentz-violating model depends on one free function of absolute velocity, but otherwise preserves as much as possible of standard Lorentz invariant physics. {\\copyright} 2012 SISSA.},\n\tart_number = {119},\n\tauthor = {Baccetti, V. and Tate, K. and Visser, M.},\n\tdate-added = {2019-03-18 11:59:12 +1100},\n\tdate-modified = {2019-03-18 11:59:12 +1100},\n\tdoi = {10.1007/JHEP05(2012)119},\n\tjournal = {Journal of High Energy Physics},\n\tnumber = {5},\n\ttitle = {Inertial frames without the relativity principle},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84861834183&doi=10.1007%2fJHEP05%282012%29119&partnerID=40&md5=84b5416b86a0abc3249b2c90ce2e9ae9},\n\tvolume = {2012},\n\tyear = {2012},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84861834183&doi=10.1007%2fJHEP05%282012%29119&partnerID=40&md5=84b5416b86a0abc3249b2c90ce2e9ae9},\n\tBdsk-Url-2 = {https://doi.org/10.1007/JHEP05(2012)119}}\n\n
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\n\n\n
\n Ever since the work of von Ignatowsky circa 1910 it has been known (if not always widely appreciated) that the relativity principle, combined with the basic and fundamental physical assumptions of locality, linearity, and isotropy, leads almost uniquely to either the Lorentz transformations of special relativity or to Galileoś transformations of classical Newtonian mechanics. Consequently, if one wishes (for whatever reason) to entertain the possibility of Lorentz symmetry breaking within the context of the class of local physical theories, then it seems likely that one will have to abandon (or at the very least grossly modify) the relativity principle. Working within the framework of local physics, we reassess the notion of spacetime transformations between inertial frames in the absence of the relativity principle, arguing that significant and nontrivial physics can still be extracted as long as the transformations are at least linear. An interesting technical aspect of the analysis is that the transformations now form a groupoid/pseudo-group - it is this technical point that permits one to evade the von Ignatowsky argument. Even in the absence of a relativity principle we can (assuming locality and linearity) nevertheless deduce clear and compelling rules for the transformation of space and time, rules for the composition of 3-velocities, and rules for the transformation of energy and momentum. Within this framework, the energy-momentum transformations are in general affine, but may be chosen to be linear, with the 4-component vector P = (E,-p T ) transforming as a row vector, while the 4-component vector of space-time position X = (t, x T ) T transforms as a column vector. As part of the analysis we identify two particularly elegant and physically compelling models implementing \"minimalist\" violations of Lorentz invariance - in the first of these minimalist models all Lorentz violations are confined to carefully delineated particle physics sub-sectors, while the second minimalist Lorentz-violating model depends on one free function of absolute velocity, but otherwise preserves as much as possible of standard Lorentz invariant physics. © 2012 SISSA.\n
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\n \n\n \n \n \n \n \n \n Lorentz violating kinematics: Threshold theorems.\n \n \n \n \n\n\n \n Baccetti, V.; Tate, K.; and Visser, M.\n\n\n \n\n\n\n Journal of High Energy Physics, 2012(3). 2012.\n \n\n\n\n
\n\n\n\n \n \n \"Lorentz link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Baccetti2012,\n\tabstract = {Recent tentative experimental indications, and the subsequent theoretical spec-ulations, regarding possible violations of Lorentz invariance have attracted a vast amount of attention. An important technical issue that considerably complicates detailed calculations in any such scenario, is that once one violates Lorentz invariance the analysis of thresh-olds in both scattering and decay processes becomes extremely subtle, with many new and naively unexpected effects. In the current article we develop several extremely general threshold theorems that depend only on the existence of some energy momentum relation E(p), eschewing even assumptions of isotropy or monotonicity. We shall argue that there are physically interesting situations where such a level of generality is called for, and that existing (partial) results in the literature make unnecessary technical assumptions. Even in this most general of settings, we show that at threshold all final state particles move with the same 3-velocity, while initial state particles must have 3-velocities parallel/anti-parallel to the final state particles. In contrast the various 3-momenta can behave in a complicated and counter-intuitive manner. {\\copyright} 2012 SISSA.},\n\tart_number = {087},\n\tauthor = {Baccetti, V. and Tate, K. and Visser, M.},\n\tdate-added = {2019-03-18 11:59:12 +1100},\n\tdate-modified = {2019-03-18 11:59:12 +1100},\n\tdoi = {10.1007/JHEP03(2012)087},\n\tjournal = {Journal of High Energy Physics},\n\tnumber = {3},\n\ttitle = {Lorentz violating kinematics: Threshold theorems},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84859582413&doi=10.1007%2fJHEP03%282012%29087&partnerID=40&md5=46408d8d43f458816a6d17522b6568a7},\n\tvolume = {2012},\n\tyear = {2012},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84859582413&doi=10.1007%2fJHEP03%282012%29087&partnerID=40&md5=46408d8d43f458816a6d17522b6568a7},\n\tBdsk-Url-2 = {https://doi.org/10.1007/JHEP03(2012)087}}\n\n
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\n Recent tentative experimental indications, and the subsequent theoretical spec-ulations, regarding possible violations of Lorentz invariance have attracted a vast amount of attention. An important technical issue that considerably complicates detailed calculations in any such scenario, is that once one violates Lorentz invariance the analysis of thresh-olds in both scattering and decay processes becomes extremely subtle, with many new and naively unexpected effects. In the current article we develop several extremely general threshold theorems that depend only on the existence of some energy momentum relation E(p), eschewing even assumptions of isotropy or monotonicity. We shall argue that there are physically interesting situations where such a level of generality is called for, and that existing (partial) results in the literature make unnecessary technical assumptions. Even in this most general of settings, we show that at threshold all final state particles move with the same 3-velocity, while initial state particles must have 3-velocities parallel/anti-parallel to the final state particles. In contrast the various 3-momenta can behave in a complicated and counter-intuitive manner. © 2012 SISSA.\n
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\n \n\n \n \n \n \n \n \n Null energy condition violations in bimetric gravity.\n \n \n \n \n\n\n \n Baccetti, V.; Martin-Moruno, P.; and Visser, M.\n\n\n \n\n\n\n Journal of High Energy Physics, 2012(8). 2012.\n \n\n\n\n
\n\n\n\n \n \n \"Null link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Baccetti2012,\n\tabstract = {We consider the effective stress-energy tensors for the foreground and background sectors in ghost-free bimetric gravity. By considering the symmetries of the theory, we show that the foreground and background null energy conditions (NECs) are strongly anti-correlated. In particular, the NECs can only be simultaneously fulfilled when they saturate, corresponding to foreground and background cosmological constants. In all other situations, either the foreground or the background is subject to a NEC-violating contribution to the total stress-energy. {\\copyright} SISSA 2012.},\n\tart_number = {148},\n\tauthor = {Baccetti, V. and Martin-Moruno, P. and Visser, M.},\n\tdate-added = {2019-03-18 11:59:12 +1100},\n\tdate-modified = {2019-03-18 11:59:12 +1100},\n\tdoi = {10.1007/JHEP08(2012)148},\n\tjournal = {Journal of High Energy Physics},\n\tnumber = {8},\n\ttitle = {Null energy condition violations in bimetric gravity},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84865783185&doi=10.1007%2fJHEP08%282012%29148&partnerID=40&md5=cbe2229db2fee8b2f6fae350a52f64dd},\n\tvolume = {2012},\n\tyear = {2012},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84865783185&doi=10.1007%2fJHEP08%282012%29148&partnerID=40&md5=cbe2229db2fee8b2f6fae350a52f64dd},\n\tBdsk-Url-2 = {https://doi.org/10.1007/JHEP08(2012)148}}\n\n
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\n We consider the effective stress-energy tensors for the foreground and background sectors in ghost-free bimetric gravity. By considering the symmetries of the theory, we show that the foreground and background null energy conditions (NECs) are strongly anti-correlated. In particular, the NECs can only be simultaneously fulfilled when they saturate, corresponding to foreground and background cosmological constants. In all other situations, either the foreground or the background is subject to a NEC-violating contribution to the total stress-energy. © SISSA 2012.\n
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\n \n\n \n \n \n \n \n \n N-photon wave packets interacting with an arbitrary quantum system.\n \n \n \n \n\n\n \n Baragiola, B.; Cook, R.; Brańczyk, A.; and Combes, J.\n\n\n \n\n\n\n Physical Review A - Atomic, Molecular, and Optical Physics, 86(1). 2012.\n \n\n\n\n
\n\n\n\n \n \n \"N-photon link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Baragiola2012,\n\tabstract = {We present a theoretical framework that describes a wave packet of light prepared in a state of definite photon number interacting with an arbitrary quantum system (e.g., a quantum harmonic oscillator or a multilevel atom). Within this framework we derive master equations for the system as well as for output field quantities such as quadratures and photon flux. These results are then generalized to wave packets with arbitrary spectral distribution functions. Finally, we obtain master equations and output field quantities for systems interacting with wave packets in multiple spatial and/or polarization modes. {\\copyright} 2012 American Physical Society.},\n\tart_number = {013811},\n\tauthor = {Baragiola, B.Q. and Cook, R.L. and Bra{\\'n}czyk, A.M. and Combes, J.},\n\tdoi = {10.1103/PhysRevA.86.013811},\n\tjournal = {Physical Review A - Atomic, Molecular, and Optical Physics},\n\tnumber = {1},\n\ttitle = {N-photon wave packets interacting with an arbitrary quantum system},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84863707293&doi=10.1103%2fPhysRevA.86.013811&partnerID=40&md5=d562d8f50cd2051bede7254cb29f345a},\n\tvolume = {86},\n\tyear = {2012},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84863707293&doi=10.1103%2fPhysRevA.86.013811&partnerID=40&md5=d562d8f50cd2051bede7254cb29f345a},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.86.013811}}\n\n
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\n We present a theoretical framework that describes a wave packet of light prepared in a state of definite photon number interacting with an arbitrary quantum system (e.g., a quantum harmonic oscillator or a multilevel atom). Within this framework we derive master equations for the system as well as for output field quantities such as quadratures and photon flux. These results are then generalized to wave packets with arbitrary spectral distribution functions. Finally, we obtain master equations and output field quantities for systems interacting with wave packets in multiple spatial and/or polarization modes. © 2012 American Physical Society.\n
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\n \n\n \n \n \n \n \n \n Temporal-mode continuous-variable cluster states using linear optics.\n \n \n \n \n\n\n \n Menicucci, N.\n\n\n \n\n\n\n Physical Review A - Atomic, Molecular, and Optical Physics, 83(6). 2011.\n \n\n\n\n
\n\n\n\n \n \n \"Temporal-mode link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Menicucci2011,\n\tabstract = {An extensible experimental design for optical continuous-variable cluster states of arbitrary size using four offline (vacuum) squeezers and six beam splitters is presented. This method has all the advantages of a temporal-mode encoding, including finite requirements for coherence and stability even as the computation length increases indefinitely, with none of the difficulty of inline squeezing. The extensibility stems from a construction based on Gaussian projected entangled pair states. The potential for use of this design within a fully fault-tolerant model is discussed. {\\copyright} 2011 American Physical Society.},\n\tart_number = {062314},\n\tauthor = {Menicucci, N.C.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1103/PhysRevA.83.062314},\n\tjournal = {Physical Review A - Atomic, Molecular, and Optical Physics},\n\tnumber = {6},\n\ttitle = {Temporal-mode continuous-variable cluster states using linear optics},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-79961038653&doi=10.1103%2fPhysRevA.83.062314&partnerID=40&md5=b12e37903fec36e02c8560cc5b4b557a},\n\tvolume = {83},\n\tyear = {2011},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-79961038653&doi=10.1103%2fPhysRevA.83.062314&partnerID=40&md5=b12e37903fec36e02c8560cc5b4b557a},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.83.062314}}\n\n
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\n An extensible experimental design for optical continuous-variable cluster states of arbitrary size using four offline (vacuum) squeezers and six beam splitters is presented. This method has all the advantages of a temporal-mode encoding, including finite requirements for coherence and stability even as the computation length increases indefinitely, with none of the difficulty of inline squeezing. The extensibility stems from a construction based on Gaussian projected entangled pair states. The potential for use of this design within a fully fault-tolerant model is discussed. © 2011 American Physical Society.\n
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\n \n\n \n \n \n \n \n \n Graphical calculus for Gaussian pure states.\n \n \n \n \n\n\n \n Menicucci, N.; Flammia, S.; and Van Loock, P.\n\n\n \n\n\n\n Physical Review A - Atomic, Molecular, and Optical Physics, 83(4). 2011.\n \n\n\n\n
\n\n\n\n \n \n \"Graphical link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{Menicucci2011,\n\tabstract = {We provide a unified graphical calculus for all Gaussian pure states, including graph transformation rules for all local and semilocal Gaussian unitary operations, as well as local quadrature measurements. We then use this graphical calculus to analyze continuous-variable (CV) cluster states, the essential resource for one-way quantum computing with CV systems. Current graphical approaches to CV cluster states are only valid in the unphysical limit of infinite squeezing, and the associated graph transformation rules only apply when the initial and final states are of this form. Our formalism applies to all Gaussian pure states and subsumes these rules in a natural way. In addition, the term "CV graph state" currently has several inequivalent definitions in use. Using this formalism we provide a single unifying definition that encompasses all of them. We provide many examples of how the formalism may be used in the context of CV cluster states: defining the "closest" CV cluster state to a given Gaussian pure state and quantifying the error in the approximation due to finite squeezing; analyzing the optimality of certain methods of generating CV cluster states; drawing connections between this graphical formalism and bosonic Hamiltonians with Gaussian ground states, including those useful for CV one-way quantum computing; and deriving a graphical measure of bipartite entanglement for certain classes of CV cluster states. We mention other possible applications of this formalism and conclude with a brief note on fault tolerance in CV one-way quantum computing. {\\copyright} 2011 American Physical Society.},\n\tart_number = {042335},\n\tauthor = {Menicucci, N.C. and Flammia, S.T. and Van Loock, P.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1103/PhysRevA.83.042335},\n\tjournal = {Physical Review A - Atomic, Molecular, and Optical Physics},\n\tnumber = {4},\n\ttitle = {Graphical calculus for Gaussian pure states},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-79960638725&doi=10.1103%2fPhysRevA.83.042335&partnerID=40&md5=d7c71a3b33c0906f789776bc5bd27e08},\n\tvolume = {83},\n\tyear = {2011},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-79960638725&doi=10.1103%2fPhysRevA.83.042335&partnerID=40&md5=d7c71a3b33c0906f789776bc5bd27e08},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.83.042335}}\n\n
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\n We provide a unified graphical calculus for all Gaussian pure states, including graph transformation rules for all local and semilocal Gaussian unitary operations, as well as local quadrature measurements. We then use this graphical calculus to analyze continuous-variable (CV) cluster states, the essential resource for one-way quantum computing with CV systems. Current graphical approaches to CV cluster states are only valid in the unphysical limit of infinite squeezing, and the associated graph transformation rules only apply when the initial and final states are of this form. Our formalism applies to all Gaussian pure states and subsumes these rules in a natural way. In addition, the term \"CV graph state\" currently has several inequivalent definitions in use. Using this formalism we provide a single unifying definition that encompasses all of them. We provide many examples of how the formalism may be used in the context of CV cluster states: defining the \"closest\" CV cluster state to a given Gaussian pure state and quantifying the error in the approximation due to finite squeezing; analyzing the optimality of certain methods of generating CV cluster states; drawing connections between this graphical formalism and bosonic Hamiltonians with Gaussian ground states, including those useful for CV one-way quantum computing; and deriving a graphical measure of bipartite entanglement for certain classes of CV cluster states. We mention other possible applications of this formalism and conclude with a brief note on fault tolerance in CV one-way quantum computing. © 2011 American Physical Society.\n
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\n  \n 2010\n \n \n (5)\n \n \n
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\n \n\n \n \n \n \n \n \n Simulating quantum effects of cosmological expansion using a static ion trap.\n \n \n \n \n\n\n \n Menicucci, N.; Olson, S.; and Milburn, G.\n\n\n \n\n\n\n New Journal of Physics, 12. 2010.\n \n\n\n\n
\n\n\n\n \n \n \"Simulating link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{Menicucci2010,\n\tabstract = {We propose a new experimental test bed that uses ions in the collective ground state of a static trap to study the analogue of quantumfield effects in cosmological spacetimes, including the Gibbons-Hawking effect for a single detector in de Sitter spacetime, as well as the possibility of modeling inflationary structure formation and the entanglement signature of de Sitter spacetime. To date, proposals for using trapped ions in analogue gravity experiments have simulated the effect of gravity on the field modes by directly manipulating the ions\\' motion. In contrast, by associating laboratory time with conformal time in the simulated universe, we can encode the full effect of curvature in the modulation of the laser used to couple the ions\\' vibrational motion and electronic states. This model simplifies the experimental requirements for modeling the analogue of an expanding universe using trapped ions, and it enlarges the validity of the ion-trap analogy to a wide range of interesting cases. {\\copyright} IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.},\n\tart_number = {095019},\n\tauthor = {Menicucci, N.C. and Olson, S.J. and Milburn, G.J.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1088/1367-2630/12/9/095019},\n\tjournal = {New Journal of Physics},\n\ttitle = {Simulating quantum effects of cosmological expansion using a static ion trap},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77958556841&doi=10.1088%2f1367-2630%2f12%2f9%2f095019&partnerID=40&md5=6dfb041b08f32095df8905881e10f03b},\n\tvolume = {12},\n\tyear = {2010},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77958556841&doi=10.1088%2f1367-2630%2f12%2f9%2f095019&partnerID=40&md5=6dfb041b08f32095df8905881e10f03b},\n\tBdsk-Url-2 = {https://doi.org/10.1088/1367-2630/12/9/095019}}\n\n
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\n\n\n
\n We propose a new experimental test bed that uses ions in the collective ground state of a static trap to study the analogue of quantumfield effects in cosmological spacetimes, including the Gibbons-Hawking effect for a single detector in de Sitter spacetime, as well as the possibility of modeling inflationary structure formation and the entanglement signature of de Sitter spacetime. To date, proposals for using trapped ions in analogue gravity experiments have simulated the effect of gravity on the field modes by directly manipulating the ions ́motion. In contrast, by associating laboratory time with conformal time in the simulated universe, we can encode the full effect of curvature in the modulation of the laser used to couple the ions ́vibrational motion and electronic states. This model simplifies the experimental requirements for modeling the analogue of an expanding universe using trapped ions, and it enlarges the validity of the ion-trap analogy to a wide range of interesting cases. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.\n
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\n \n\n \n \n \n \n \n \n Arbitrarily large continuous-variable cluster states from a single quantum nondemolition gate.\n \n \n \n \n\n\n \n Menicucci, N.; Ma, X.; and Ralph, T.\n\n\n \n\n\n\n Physical Review Letters, 104(25). 2010.\n \n\n\n\n
\n\n\n\n \n \n \"Arbitrarily link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{Menicucci2010,\n\tabstract = {We present a compact experimental design for producing an arbitrarily large optical continuous-variable cluster state using just one single-mode vacuum squeezer and one quantum nondemolition gate. Generating the cluster state and computing with it happen simultaneously: more entangled modes become available as previous modes are measured, thereby making finite the requirements for coherence and stability even as the computation length increases indefinitely. {\\copyright} 2010 The American Physical Society.},\n\tart_number = {250503},\n\tauthor = {Menicucci, N.C. and Ma, X. and Ralph, T.C.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1103/PhysRevLett.104.250503},\n\tjournal = {Physical Review Letters},\n\tnumber = {25},\n\ttitle = {Arbitrarily large continuous-variable cluster states from a single quantum nondemolition gate},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77953923601&doi=10.1103%2fPhysRevLett.104.250503&partnerID=40&md5=d76941f690090af4307e75f8a7cf69a1},\n\tvolume = {104},\n\tyear = {2010},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77953923601&doi=10.1103%2fPhysRevLett.104.250503&partnerID=40&md5=d76941f690090af4307e75f8a7cf69a1},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevLett.104.250503}}\n\n
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\n\n\n
\n We present a compact experimental design for producing an arbitrarily large optical continuous-variable cluster state using just one single-mode vacuum squeezer and one quantum nondemolition gate. Generating the cluster state and computing with it happen simultaneously: more entangled modes become available as previous modes are measured, thereby making finite the requirements for coherence and stability even as the computation length increases indefinitely. © 2010 The American Physical Society.\n
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\n \n\n \n \n \n \n \n \n A competitive game whose maximal Nash-equilibrium payoff requires quantum resources for its achievement.\n \n \n \n \n\n\n \n Hill, C.; Flitney, A.; and Menicucci, N.\n\n\n \n\n\n\n Physics Letters, Section A: General, Atomic and Solid State Physics, 374(35). 2010.\n \n\n\n\n
\n\n\n\n \n \n \"A link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Hill20103619,\n\tabstract = {While it is known that shared quantum entanglement can offer improved solutions to a number of purely cooperative tasks for groups of remote agents, controversy remains regarding the legitimacy of quantum games in a competitive setting. We construct a competitive game between four players based on the minority game where the maximal Nash-equilibrium payoff when played with the appropriate quantum resource is greater than that obtainable by classical means, assuming a local hidden variable model. {\\copyright} 2010 Elsevier B.V. All rights reserved.},\n\tart_number = {3619-3624},\n\tauthor = {Hill, C.D. and Flitney, A.P. and Menicucci, N.C.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-19 16:35:51 +1100},\n\tdoi = {10.1016/j.physleta.2010.07.010},\n\tjournal = {Physics Letters, Section A: General, Atomic and Solid State Physics},\n\tnumber = {35},\n\ttitle = {A competitive game whose maximal Nash-equilibrium payoff requires quantum resources for its achievement},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77955473082&doi=10.1016%2fj.physleta.2010.07.010&partnerID=40&md5=51d3bc24cfb9ba12c2f3961a628a762d},\n\tvolume = {374},\n\tyear = {2010},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77955473082&doi=10.1016%2fj.physleta.2010.07.010&partnerID=40&md5=51d3bc24cfb9ba12c2f3961a628a762d},\n\tBdsk-Url-2 = {https://doi.org/10.1016/j.physleta.2010.07.010}}\n\n
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\n While it is known that shared quantum entanglement can offer improved solutions to a number of purely cooperative tasks for groups of remote agents, controversy remains regarding the legitimacy of quantum games in a competitive setting. We construct a competitive game between four players based on the minority game where the maximal Nash-equilibrium payoff when played with the appropriate quantum resource is greater than that obtainable by classical means, assuming a local hidden variable model. © 2010 Elsevier B.V. All rights reserved.\n
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\n \n\n \n \n \n \n \n \n The particle interpretation of N = 1 supersymmetric spin foams.\n \n \n \n \n\n\n \n Baccetti, V.; Livine, E.; and Ryan, J.\n\n\n \n\n\n\n Classical and Quantum Gravity, 27(22). 2010.\n \n\n\n\n
\n\n\n\n \n \n \"The link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{Baccetti2010,\n\tabstract = {We show that N = 1-supersymmetric BF theory in 3D leads to a supersymmetric spin foam amplitude via a lattice discretization. Furthermore, by analysing the supersymmetric quantum amplitudes, we show that they can be re-interpreted as 3D gravity coupled to embedded fermionic Feynman diagrams. {\\copyright} 2010 IOP Publishing Ltd.},\n\tart_number = {225022},\n\tauthor = {Baccetti, V. and Livine, E.R. and Ryan, J.P.},\n\tdate-added = {2019-03-18 11:59:12 +1100},\n\tdate-modified = {2019-03-18 11:59:12 +1100},\n\tdoi = {10.1088/0264-9381/27/22/225022},\n\tjournal = {Classical and Quantum Gravity},\n\tnumber = {22},\n\ttitle = {The particle interpretation of N = 1 supersymmetric spin foams},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-78649855241&doi=10.1088%2f0264-9381%2f27%2f22%2f225022&partnerID=40&md5=79e55d7e4e5bd0e08c5e4a781cf6f1f3},\n\tvolume = {27},\n\tyear = {2010},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-78649855241&doi=10.1088%2f0264-9381%2f27%2f22%2f225022&partnerID=40&md5=79e55d7e4e5bd0e08c5e4a781cf6f1f3},\n\tBdsk-Url-2 = {https://doi.org/10.1088/0264-9381/27/22/225022}}\n\n
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\n We show that N = 1-supersymmetric BF theory in 3D leads to a supersymmetric spin foam amplitude via a lattice discretization. Furthermore, by analysing the supersymmetric quantum amplitudes, we show that they can be re-interpreted as 3D gravity coupled to embedded fermionic Feynman diagrams. © 2010 IOP Publishing Ltd.\n
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\n \n\n \n \n \n \n \n \n Collective uncertainty in partially polarized and partially decohered spin-12 systems.\n \n \n \n \n\n\n \n Baragiola, B.; Chase, B.; and Geremia, J.\n\n\n \n\n\n\n Physical Review A - Atomic, Molecular, and Optical Physics, 81(3). 2010.\n \n\n\n\n
\n\n\n\n \n \n \"Collective link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Baragiola2010,\n\tabstract = {It has become common practice to model large spin ensembles as an effective pseudospin with total angular momentum J=Nj, where j is the spin per particle. Such approaches (at least implicitly) restrict the quantum state of the ensemble to the so-called symmetric Hilbert space. Here, we argue that symmetric states are not generally well preserved under the type of decoherence typical of experiments involving large clouds of atoms or ions. In particular, symmetric states are rapidly degraded under models of decoherence that act identically but locally on the different members of the ensemble. Using an approach that is not limited to the symmetric Hilbert space, we explore potential pitfalls in the design and interpretation of experiments on spin-squeezing and collective atomic phenomena when the properties of the symmetric states are extended to systems where they do not apply. {\\copyright} 2010 The American Physical Society.},\n\tart_number = {032104},\n\tauthor = {Baragiola, B.Q. and Chase, B.A. and Geremia, J.},\n\tdoi = {10.1103/PhysRevA.81.032104},\n\tjournal = {Physical Review A - Atomic, Molecular, and Optical Physics},\n\tnumber = {3},\n\ttitle = {Collective uncertainty in partially polarized and partially decohered spin-12 systems},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77950416481&doi=10.1103%2fPhysRevA.81.032104&partnerID=40&md5=b14ebe432a493dca1273b565a45e3fb5},\n\tvolume = {81},\n\tyear = {2010},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77950416481&doi=10.1103%2fPhysRevA.81.032104&partnerID=40&md5=b14ebe432a493dca1273b565a45e3fb5},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.81.032104}}\n\n
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\n It has become common practice to model large spin ensembles as an effective pseudospin with total angular momentum J=Nj, where j is the spin per particle. Such approaches (at least implicitly) restrict the quantum state of the ensemble to the so-called symmetric Hilbert space. Here, we argue that symmetric states are not generally well preserved under the type of decoherence typical of experiments involving large clouds of atoms or ions. In particular, symmetric states are rapidly degraded under models of decoherence that act identically but locally on the different members of the ensemble. Using an approach that is not limited to the symmetric Hilbert space, we explore potential pitfalls in the design and interpretation of experiments on spin-squeezing and collective atomic phenomena when the properties of the symmetric states are extended to systems where they do not apply. © 2010 The American Physical Society.\n
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\n  \n 2009\n \n \n (4)\n \n \n
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\n \n\n \n \n \n \n \n \n The optical frequency comb as a one-way quantum computer.\n \n \n \n \n\n\n \n Flammia, S.; Menicucci, N.; and Pfister, O.\n\n\n \n\n\n\n Journal of Physics B: Atomic, Molecular and Optical Physics, 42(11). 2009.\n \n\n\n\n
\n\n\n\n \n \n \"The link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Flammia2009,\n\tabstract = {In the one-way model of quantum computing, quantum algorithms are implemented using only measurements on an entangled initial state. Much of the hard work is done upfront when creating this universal resource, known as a cluster state, on which the measurements are made. Here we detail a new proposal for a scalable method of creating cluster states using only a single multimode optical parametric oscillator (OPO). The method generates a continuous-variable cluster state that is universal for quantum computation and encoded in the quadratures of the optical frequency comb of the OPO. This work expands on the presentation in Menicucci, Flammia and Pfister (2008 Phys. Rev. Lett. 101, 130501). {\\copyright} 2009 IOP Publishing Ltd.},\n\tart_number = {114009},\n\tauthor = {Flammia, S.T. and Menicucci, N.C. and Pfister, O.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1088/0953-4075/42/11/114009},\n\tjournal = {Journal of Physics B: Atomic, Molecular and Optical Physics},\n\tnumber = {11},\n\ttitle = {The optical frequency comb as a one-way quantum computer},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-67651018244&doi=10.1088%2f0953-4075%2f42%2f11%2f114009&partnerID=40&md5=583c52761f19b3c447587ea72272ad51},\n\tvolume = {42},\n\tyear = {2009},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-67651018244&doi=10.1088%2f0953-4075%2f42%2f11%2f114009&partnerID=40&md5=583c52761f19b3c447587ea72272ad51},\n\tBdsk-Url-2 = {https://doi.org/10.1088/0953-4075/42/11/114009}}\n\n
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\n In the one-way model of quantum computing, quantum algorithms are implemented using only measurements on an entangled initial state. Much of the hard work is done upfront when creating this universal resource, known as a cluster state, on which the measurements are made. Here we detail a new proposal for a scalable method of creating cluster states using only a single multimode optical parametric oscillator (OPO). The method generates a continuous-variable cluster state that is universal for quantum computation and encoded in the quadratures of the optical frequency comb of the OPO. This work expands on the presentation in Menicucci, Flammia and Pfister (2008 Phys. Rev. Lett. 101, 130501). © 2009 IOP Publishing Ltd.\n
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\n \n\n \n \n \n \n \n \n Quantum computing with continuous-variable clusters.\n \n \n \n \n\n\n \n Gu, M.; Weedbrook, C.; Menicucci, N.; Ralph, T.; and Van Loock, P.\n\n\n \n\n\n\n Physical Review A - Atomic, Molecular, and Optical Physics, 79(6). 2009.\n \n\n\n\n
\n\n\n\n \n \n \"Quantum link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Gu2009,\n\tabstract = {Continuous-variable cluster states offer a potentially promising method of implementing a quantum computer. This paper extends and further refines theoretical foundations and protocols for experimental implementation. We give a cluster-state implementation of the cubic phase gate through photon detection, which, together with homodyne detection, facilitates universal quantum computation. In addition, we characterize the offline squeezed resources required to generate an arbitrary graph state through passive linear optics. Most significantly, we prove that there are universal states for which the offline squeezing per mode does not increase with the size of the cluster. Simple representations of continuous-variable graph states are introduced to analyze graph state transformations under measurement and the existence of universal continuous-variable resource states. {\\copyright} 2009 The American Physical Society.},\n\tart_number = {062318},\n\tauthor = {Gu, M. and Weedbrook, C. and Menicucci, N.C. and Ralph, T.C. and Van Loock, P.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1103/PhysRevA.79.062318},\n\tjournal = {Physical Review A - Atomic, Molecular, and Optical Physics},\n\tnumber = {6},\n\ttitle = {Quantum computing with continuous-variable clusters},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-67549137432&doi=10.1103%2fPhysRevA.79.062318&partnerID=40&md5=dc80b51ddc4bd0f2497e37008ed0728a},\n\tvolume = {79},\n\tyear = {2009},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-67549137432&doi=10.1103%2fPhysRevA.79.062318&partnerID=40&md5=dc80b51ddc4bd0f2497e37008ed0728a},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.79.062318}}\n\n
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\n Continuous-variable cluster states offer a potentially promising method of implementing a quantum computer. This paper extends and further refines theoretical foundations and protocols for experimental implementation. We give a cluster-state implementation of the cubic phase gate through photon detection, which, together with homodyne detection, facilitates universal quantum computation. In addition, we characterize the offline squeezed resources required to generate an arbitrary graph state through passive linear optics. Most significantly, we prove that there are universal states for which the offline squeezing per mode does not increase with the size of the cluster. Simple representations of continuous-variable graph states are introduced to analyze graph state transformations under measurement and the existence of universal continuous-variable resource states. © 2009 The American Physical Society.\n
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\n \n\n \n \n \n \n \n \n Entangling power of an expanding universe.\n \n \n \n \n\n\n \n Steeg, G.; and Menicucci, N.\n\n\n \n\n\n\n Physical Review D - Particles, Fields, Gravitation and Cosmology, 79(4). 2009.\n \n\n\n\n
\n\n\n\n \n \n \"Entangling link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Steeg2009,\n\tabstract = {We show that entanglement can be used to detect spacetime curvature. Quantum fields in the Minkowski vacuum are entangled with respect to local field modes. This entanglement can be swapped to spatially separated quantum systems using standard local couplings. A single, inertial field detector in the exponentially expanding (de Sitter) vacuum responds as if it were bathed in thermal radiation in a Minkowski universe. We show that using two inertial detectors, interactions with the field in the thermal case will entangle certain detector pairs that would not become entangled in the corresponding de Sitter case. The two universes can thus be distinguished by their entangling power. {\\copyright} 2009 The American Physical Society.},\n\tart_number = {044027},\n\tauthor = {Steeg, G.V. and Menicucci, N.C.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1103/PhysRevD.79.044027},\n\tjournal = {Physical Review D - Particles, Fields, Gravitation and Cosmology},\n\tnumber = {4},\n\ttitle = {Entangling power of an expanding universe},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-62549107557&doi=10.1103%2fPhysRevD.79.044027&partnerID=40&md5=9919f80d1eddbbbcb61ad3c83addb723},\n\tvolume = {79},\n\tyear = {2009},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-62549107557&doi=10.1103%2fPhysRevD.79.044027&partnerID=40&md5=9919f80d1eddbbbcb61ad3c83addb723},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevD.79.044027}}\n\n
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\n We show that entanglement can be used to detect spacetime curvature. Quantum fields in the Minkowski vacuum are entangled with respect to local field modes. This entanglement can be swapped to spatially separated quantum systems using standard local couplings. A single, inertial field detector in the exponentially expanding (de Sitter) vacuum responds as if it were bathed in thermal radiation in a Minkowski universe. We show that using two inertial detectors, interactions with the field in the thermal case will entangle certain detector pairs that would not become entangled in the corresponding de Sitter case. The two universes can thus be distinguished by their entangling power. © 2009 The American Physical Society.\n
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\n \n\n \n \n \n \n \n \n Magnetometry via a double-pass continuous quantum measurement of atomic spin.\n \n \n \n \n\n\n \n Chase, B.; Baragiola, B.; Partner, H.; Black, B.; and Geremia, J.\n\n\n \n\n\n\n Physical Review A - Atomic, Molecular, and Optical Physics, 79(6). 2009.\n \n\n\n\n
\n\n\n\n \n \n \"Magnetometry link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Chase2009,\n\tabstract = {We argue that it is possible in principle to reduce the uncertainty of an atomic magnetometer by double passing a far-detuned laser field through the atomic sample as it undergoes Larmor precession. Numerical simulations of the quantum Fisher information suggest that, despite the lack of explicit multibody coupling terms in the system\\'s magnetic Hamiltonian, the parameter estimation uncertainty in such a physical setup scales better than the conventional Heisenberg uncertainty limit over a specified but arbitrary range of particle number. Using the methods of quantum stochastic calculus and filtering theory, we demonstrate numerically an explicit parameter estimator (called a quantum particle filter) whose observed scaling follows that of our calculated quantum Fisher information. Moreover, the quantum particle filter quantitatively surpasses the uncertainty limit calculated from the quantum Cram{\\'e}r-Rao inequality based on a magnetic coupling Hamiltonian with only single-body operators. We also show that a quantum Kalman filter is insufficient to obtain super-Heisenberg scaling and present evidence that such scaling necessitates going beyond the manifold of Gaussian atomic states. {\\copyright} 2009 The American Physical Society.},\n\tart_number = {062107},\n\tauthor = {Chase, B.A. and Baragiola, B.Q. and Partner, H.L. and Black, B.D. and Geremia, J.M.},\n\tdoi = {10.1103/PhysRevA.79.062107},\n\tjournal = {Physical Review A - Atomic, Molecular, and Optical Physics},\n\tnumber = {6},\n\ttitle = {Magnetometry via a double-pass continuous quantum measurement of atomic spin},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-67249118734&doi=10.1103%2fPhysRevA.79.062107&partnerID=40&md5=1b9958f2158a09ee6a398702fccefcaa},\n\tvolume = {79},\n\tyear = {2009},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-67249118734&doi=10.1103%2fPhysRevA.79.062107&partnerID=40&md5=1b9958f2158a09ee6a398702fccefcaa},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.79.062107}}\n
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\n\n\n
\n We argue that it is possible in principle to reduce the uncertainty of an atomic magnetometer by double passing a far-detuned laser field through the atomic sample as it undergoes Larmor precession. Numerical simulations of the quantum Fisher information suggest that, despite the lack of explicit multibody coupling terms in the systemś magnetic Hamiltonian, the parameter estimation uncertainty in such a physical setup scales better than the conventional Heisenberg uncertainty limit over a specified but arbitrary range of particle number. Using the methods of quantum stochastic calculus and filtering theory, we demonstrate numerically an explicit parameter estimator (called a quantum particle filter) whose observed scaling follows that of our calculated quantum Fisher information. Moreover, the quantum particle filter quantitatively surpasses the uncertainty limit calculated from the quantum Cramér-Rao inequality based on a magnetic coupling Hamiltonian with only single-body operators. We also show that a quantum Kalman filter is insufficient to obtain super-Heisenberg scaling and present evidence that such scaling necessitates going beyond the manifold of Gaussian atomic states. © 2009 The American Physical Society.\n
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\n  \n 2008\n \n \n (3)\n \n \n
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\n \n\n \n \n \n \n \n \n Playing the quantum harp: Multipartite squeezing and entanglement of harmonic oscillators.\n \n \n \n \n\n\n \n Pfister, O.; Menicucci, N.; Flammia, S.; Zaidi, H.; Bloomer, R.; and Pysher, M.\n\n\n \n\n\n\n 2008.\n \n\n\n\n
\n\n\n\n \n \n \"Playing link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@conference{Pfister2008,\n\tabstract = {The frequency comb of an optical resonator is a naturally large set of exquisitely well defined quantum systems, such as in the broadband mode-locked lasers which have redefined time/frequency metrology and ultraprecise measurements in recent years. High coherence can therefore be expected in the quantum version of the frequency comb, in which nonlinear interactions couple different cavity modes, as can be modeled by different forms of graph states. We show that is possible to thereby generate states of interest to quantum metrology and computing, such as multipartite entangled cluster and Greenberger-Horne-Zeilinger states.},\n\tart_number = {690603},\n\tauthor = {Pfister, O. and Menicucci, N.C. and Flammia, S.T. and Zaidi, H. and Bloomer, R. and Pysher, M.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1117/12.762995},\n\tjournal = {Proceedings of SPIE - The International Society for Optical Engineering},\n\ttitle = {Playing the quantum harp: Multipartite squeezing and entanglement of harmonic oscillators},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-40949134282&doi=10.1117%2f12.762995&partnerID=40&md5=35fb2ec464b1ce81746116c75606b741},\n\tvolume = {6906},\n\tyear = {2008},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-40949134282&doi=10.1117%2f12.762995&partnerID=40&md5=35fb2ec464b1ce81746116c75606b741},\n\tBdsk-Url-2 = {https://doi.org/10.1117/12.762995}}\n\n
\n
\n\n\n
\n The frequency comb of an optical resonator is a naturally large set of exquisitely well defined quantum systems, such as in the broadband mode-locked lasers which have redefined time/frequency metrology and ultraprecise measurements in recent years. High coherence can therefore be expected in the quantum version of the frequency comb, in which nonlinear interactions couple different cavity modes, as can be modeled by different forms of graph states. We show that is possible to thereby generate states of interest to quantum metrology and computing, such as multipartite entangled cluster and Greenberger-Horne-Zeilinger states.\n
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\n \n\n \n \n \n \n \n \n One-way quantum computing in the optical frequency comb.\n \n \n \n \n\n\n \n Menicucci, N.; Flammia, S.; and Pfister, O.\n\n\n \n\n\n\n Physical Review Letters, 101(13). 2008.\n \n\n\n\n
\n\n\n\n \n \n \"One-way link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{Menicucci2008,\n\tabstract = {One-way quantum computing allows any quantum algorithm to be implemented easily using just measurements. The difficult part is creating the universal resource, a cluster state, on which the measurements are made. We propose a scalable method that uses a single, multimode optical parametric oscillator (OPO). The method is very efficient and generates a continuous-variable cluster state, universal for quantum computation, with quantum information encoded in the quadratures of the optical frequency comb of the OPO. {\\copyright} 2008 The American Physical Society.},\n\tart_number = {130501},\n\tauthor = {Menicucci, N.C. and Flammia, S.T. and Pfister, O.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1103/PhysRevLett.101.130501},\n\tjournal = {Physical Review Letters},\n\tnumber = {13},\n\ttitle = {One-way quantum computing in the optical frequency comb},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-52949086126&doi=10.1103%2fPhysRevLett.101.130501&partnerID=40&md5=06d539aeb03ad7956594f1f4ac335f6c},\n\tvolume = {101},\n\tyear = {2008},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-52949086126&doi=10.1103%2fPhysRevLett.101.130501&partnerID=40&md5=06d539aeb03ad7956594f1f4ac335f6c},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevLett.101.130501}}\n\n
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\n One-way quantum computing allows any quantum algorithm to be implemented easily using just measurements. The difficult part is creating the universal resource, a cluster state, on which the measurements are made. We propose a scalable method that uses a single, multimode optical parametric oscillator (OPO). The method is very efficient and generates a continuous-variable cluster state, universal for quantum computation, with quantum information encoded in the quadratures of the optical frequency comb of the OPO. © 2008 The American Physical Society.\n
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\n \n\n \n \n \n \n \n \n Entangling the optical frequency comb: Simultaneous generation of multiple 2 × 2 and 2 × 3 continuous-variable cluster states in a single optical parametric oscillator.\n \n \n \n \n\n\n \n Zaidi, H.; Menicucci, N.; Flammia, S.; Bloomer, R.; Pysher, M.; and Pfister, O.\n\n\n \n\n\n\n Laser Physics, 18(5). 2008.\n \n\n\n\n
\n\n\n\n \n \n \"Entangling link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Zaidi2008659,\n\tabstract = {We report on our research effort to generate large-scale multipartite optical-mode entanglement using as few physical resources as possible. We have previously shown that cluster-and GHZ-type N-partite continuous-variable entanglement can be obtained in an optical resonator that contains a suitably designed second-order nonlinear optical medium, pumped by at most O(N 2) fields. In this paper, we show that the frequency comb of such a resonator can be entangled in an arbitrary number of independent 2 × 2 and 2 × 3 continuousvariable cluster states by a single optical parametric oscillator pumped by just a few optical modes. {\\copyright} 2008 Pleiades Publishing, Ltd.},\n\tart_number = {659-666},\n\tauthor = {Zaidi, H. and Menicucci, N.C. and Flammia, S.T. and Bloomer, R. and Pysher, M. and Pfister, O.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-19 16:35:21 +1100},\n\tdoi = {10.1134/S1054660X08050186},\n\tjournal = {Laser Physics},\n\tnumber = {5},\n\ttitle = {Entangling the optical frequency comb: Simultaneous generation of multiple 2 × 2 and 2 × 3 continuous-variable cluster states in a single optical parametric oscillator},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-44349192168&doi=10.1134%2fS1054660X08050186&partnerID=40&md5=b749d83188f0ffc59cc05269731e086f},\n\tvolume = {18},\n\tyear = {2008},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-44349192168&doi=10.1134%2fS1054660X08050186&partnerID=40&md5=b749d83188f0ffc59cc05269731e086f},\n\tBdsk-Url-2 = {https://doi.org/10.1134/S1054660X08050186}}\n\n
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\n We report on our research effort to generate large-scale multipartite optical-mode entanglement using as few physical resources as possible. We have previously shown that cluster-and GHZ-type N-partite continuous-variable entanglement can be obtained in an optical resonator that contains a suitably designed second-order nonlinear optical medium, pumped by at most O(N 2) fields. In this paper, we show that the frequency comb of such a resonator can be entangled in an arbitrary number of independent 2 × 2 and 2 × 3 continuousvariable cluster states by a single optical parametric oscillator pumped by just a few optical modes. © 2008 Pleiades Publishing, Ltd.\n
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\n  \n 2007\n \n \n (3)\n \n \n
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\n \n\n \n \n \n \n \n \n Ultracompact generation of continuous-variable cluster states.\n \n \n \n \n\n\n \n Menicucci, N.; Flammia, S.; Zaidi, H.; and Pfister, O.\n\n\n \n\n\n\n Physical Review A - Atomic, Molecular, and Optical Physics, 76(1). 2007.\n \n\n\n\n
\n\n\n\n \n \n \"Ultracompact link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Menicucci2007,\n\tabstract = {We propose an experimental scheme that has the potential for large-scale realization of continuous-variable (CV) cluster states for universal quantum computation. We do this by mapping CV cluster-state graphs onto two-mode squeezing graphs, which can be engineered into a single optical parametric oscillator (OPO). The desired CV cluster state is produced directly from a joint squeezing operation on the vacuum, using a multifrequency pump beam. This method has potential for ultracompact experimental implementation. As an illustration, we detail an experimental proposal for creating a four-mode square CV cluster state with a single OPO. {\\copyright} 2007 The American Physical Society.},\n\tart_number = {010302},\n\tauthor = {Menicucci, N.C. and Flammia, S.T. and Zaidi, H. and Pfister, O.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1103/PhysRevA.76.010302},\n\tjournal = {Physical Review A - Atomic, Molecular, and Optical Physics},\n\tnumber = {1},\n\ttitle = {Ultracompact generation of continuous-variable cluster states},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547152016&doi=10.1103%2fPhysRevA.76.010302&partnerID=40&md5=f22ac02f88e61456cbcdba3523701bff},\n\tvolume = {76},\n\tyear = {2007},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547152016&doi=10.1103%2fPhysRevA.76.010302&partnerID=40&md5=f22ac02f88e61456cbcdba3523701bff},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.76.010302}}\n\n
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\n We propose an experimental scheme that has the potential for large-scale realization of continuous-variable (CV) cluster states for universal quantum computation. We do this by mapping CV cluster-state graphs onto two-mode squeezing graphs, which can be engineered into a single optical parametric oscillator (OPO). The desired CV cluster state is produced directly from a joint squeezing operation on the vacuum, using a multifrequency pump beam. This method has potential for ultracompact experimental implementation. As an illustration, we detail an experimental proposal for creating a four-mode square CV cluster state with a single OPO. © 2007 The American Physical Society.\n
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\n \n\n \n \n \n \n \n \n Single trapped ion as a time-dependent harmonic oscillator.\n \n \n \n \n\n\n \n Menicucci, N.; and Milburn, G.\n\n\n \n\n\n\n Physical Review A - Atomic, Molecular, and Optical Physics, 76(5). 2007.\n \n\n\n\n
\n\n\n\n \n \n \"Single link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Menicucci2007,\n\tabstract = {We show how a single trapped ion may be used to test a variety of important physical models realized as time-dependent harmonic oscillators. The ion itself functions as its own motional detector through laser-induced electronic transitions. Alsing, [Phys. Rev. Lett. 94, 220401 (2005)] proposed that an exponentially decaying trap frequency could be used to simulate (thermal) Gibbons-Hawking radiation in an expanding universe, but the Hamiltonian used was incorrect. We apply our general solution to this experimental proposal, correcting the result for a single ion and showing that while the actual spectrum is different from the Gibbons-Hawking case, it nevertheless shares an important experimental signature with this result. {\\copyright} 2007 The American Physical Society.},\n\tart_number = {052105},\n\tauthor = {Menicucci, N.C. and Milburn, G.J.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1103/PhysRevA.76.052105},\n\tjournal = {Physical Review A - Atomic, Molecular, and Optical Physics},\n\tnumber = {5},\n\ttitle = {Single trapped ion as a time-dependent harmonic oscillator},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-36148978977&doi=10.1103%2fPhysRevA.76.052105&partnerID=40&md5=522be7dc61c9342900d1d7aff152bdf6},\n\tvolume = {76},\n\tyear = {2007},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-36148978977&doi=10.1103%2fPhysRevA.76.052105&partnerID=40&md5=522be7dc61c9342900d1d7aff152bdf6},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevA.76.052105}}\n\n
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\n We show how a single trapped ion may be used to test a variety of important physical models realized as time-dependent harmonic oscillators. The ion itself functions as its own motional detector through laser-induced electronic transitions. Alsing, [Phys. Rev. Lett. 94, 220401 (2005)] proposed that an exponentially decaying trap frequency could be used to simulate (thermal) Gibbons-Hawking radiation in an expanding universe, but the Hamiltonian used was incorrect. We apply our general solution to this experimental proposal, correcting the result for a single ion and showing that while the actual spectrum is different from the Gibbons-Hawking case, it nevertheless shares an important experimental signature with this result. © 2007 The American Physical Society.\n
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\n \n\n \n \n \n \n \n \n Compact optical generation of continuous-variable graph states.\n \n \n \n \n\n\n \n Pfister, O.; Zaidi, H.; Menicucci, N.; and Flammia, S.\n\n\n \n\n\n\n 2007.\n \n\n\n\n
\n\n\n\n \n \n \"Compact link\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@conference{Pfister2007,\n\tabstract = {We report on our current efforts to compactly generate Gaussian continuous-variable graph states, with the goal to create large-scale cluster states for one-way quantum computing. {\\copyright} 2007 OSA.},\n\tauthor = {Pfister, O. and Zaidi, H. and Menicucci, N.C. and Flammia, S.T.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tjournal = {Optics InfoBase Conference Papers},\n\ttitle = {Compact optical generation of continuous-variable graph states},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84898935020&partnerID=40&md5=e3950047e0a575bf3e856dd473243f09},\n\tyear = {2007},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84898935020&partnerID=40&md5=e3950047e0a575bf3e856dd473243f09}}\n\n
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\n We report on our current efforts to compactly generate Gaussian continuous-variable graph states, with the goal to create large-scale cluster states for one-way quantum computing. © 2007 OSA.\n
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\n  \n 2006\n \n \n (1)\n \n \n
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\n \n\n \n \n \n \n \n \n Universal quantum computation with continuous-variable cluster states.\n \n \n \n \n\n\n \n Menicucci, N.; Van Loock, P.; Gu, M.; Weedbrook, C.; Ralph, T.; and Nielsen, M.\n\n\n \n\n\n\n Physical Review Letters, 97(11). 2006.\n \n\n\n\n
\n\n\n\n \n \n \"Universal link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Menicucci2006,\n\tabstract = {We describe a generalization of the cluster-state model of quantum computation to continuous-variable systems, along with a proposal for an optical implementation using squeezed-light sources, linear optics, and homodyne detection. For universal quantum computation, a nonlinear element is required. This can be satisfied by adding to the toolbox any single-mode non-Gaussian measurement, while the initial cluster state itself remains Gaussian. Homodyne detection alone suffices to perform an arbitrary multimode Gaussian transformation via the cluster state. We also propose an experiment to demonstrate cluster-based error reduction when implementing Gaussian operations. {\\copyright} 2006 The American Physical Society.},\n\tart_number = {110501},\n\tauthor = {Menicucci, N.C. and Van Loock, P. and Gu, M. and Weedbrook, C. and Ralph, T.C. and Nielsen, M.A.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1103/PhysRevLett.97.110501},\n\tjournal = {Physical Review Letters},\n\tnumber = {11},\n\ttitle = {Universal quantum computation with continuous-variable cluster states},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33748707175&doi=10.1103%2fPhysRevLett.97.110501&partnerID=40&md5=e3ff00ff7e691ec8282889aa07facb4b},\n\tvolume = {97},\n\tyear = {2006},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33748707175&doi=10.1103%2fPhysRevLett.97.110501&partnerID=40&md5=e3ff00ff7e691ec8282889aa07facb4b},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevLett.97.110501}}\n\n
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\n We describe a generalization of the cluster-state model of quantum computation to continuous-variable systems, along with a proposal for an optical implementation using squeezed-light sources, linear optics, and homodyne detection. For universal quantum computation, a nonlinear element is required. This can be satisfied by adding to the toolbox any single-mode non-Gaussian measurement, while the initial cluster state itself remains Gaussian. Homodyne detection alone suffices to perform an arbitrary multimode Gaussian transformation via the cluster state. We also propose an experiment to demonstrate cluster-based error reduction when implementing Gaussian operations. © 2006 The American Physical Society.\n
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\n  \n 2005\n \n \n (1)\n \n \n
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\n \n\n \n \n \n \n \n \n Dynamic simulation of the superfluid/normal fluid interface motion in 4He.\n \n \n \n \n\n\n \n Xie, Z.; Menicucci, N.; Boyd, S.; Sergatskov, D.; and Duncan, R.\n\n\n \n\n\n\n Journal of Low Temperature Physics, 138(1-2). 2005.\n \n\n\n\n
\n\n\n\n \n \n \"Dynamic link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Xie200579,\n\tabstract = {We report on the development of a fully time-dependent computer simulation of the 4He normal fluid/superfluid (He-I/He-II) interface dynamics. Both the diverging thermal conductivity and the rapidly changing heat capacity of 4He near the lamda point present a challenge to traditional numerical methods for integrating the heat diffusion equation. We use the Dupont-II three-time-level method known for its good convergence properties for strong nonlinear models. Still, this algorithm does not conserve energy precisely, so a supplementary convergence criterion based on absolute enthalpy error is developed. We report on the underlying theoretical model, the numerical algorithm and its implementation, and simulation results. We compare the results with experimental data and discuss the error analysis and the balance between simulation fidelity and convergence. {\\copyright} Springer Science+Business Media, Inc. 2005.},\n\tart_number = {79-84},\n\tauthor = {Xie, Z. and Menicucci, N.C. and Boyd, S.T.P. and Sergatskov, D.A. and Duncan, R.V.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-19 16:35:14 +1100},\n\tdoi = {10.1007/s10909-005-1531-9},\n\tjournal = {Journal of Low Temperature Physics},\n\tnumber = {1-2},\n\ttitle = {Dynamic simulation of the superfluid/normal fluid interface motion in 4He},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-23944462180&doi=10.1007%2fs10909-005-1531-9&partnerID=40&md5=19ac27b833bcaf8cfb06614efc3ae314},\n\tvolume = {138},\n\tyear = {2005},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-23944462180&doi=10.1007%2fs10909-005-1531-9&partnerID=40&md5=19ac27b833bcaf8cfb06614efc3ae314},\n\tBdsk-Url-2 = {https://doi.org/10.1007/s10909-005-1531-9}}\n\n
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\n We report on the development of a fully time-dependent computer simulation of the 4He normal fluid/superfluid (He-I/He-II) interface dynamics. Both the diverging thermal conductivity and the rapidly changing heat capacity of 4He near the lamda point present a challenge to traditional numerical methods for integrating the heat diffusion equation. We use the Dupont-II three-time-level method known for its good convergence properties for strong nonlinear models. Still, this algorithm does not conserve energy precisely, so a supplementary convergence criterion based on absolute enthalpy error is developed. We report on the underlying theoretical model, the numerical algorithm and its implementation, and simulation results. We compare the results with experimental data and discuss the error analysis and the balance between simulation fidelity and convergence. © Springer Science+Business Media, Inc. 2005.\n
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\n  \n 2004\n \n \n (1)\n \n \n
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\n \n\n \n \n \n \n \n \n Fisher information with respect to cumulants.\n \n \n \n \n\n\n \n Prasad, S.; and Menicucci, N.\n\n\n \n\n\n\n IEEE Transactions on Information Theory, 50(4). 2004.\n \n\n\n\n
\n\n\n\n \n \n \"Fisher link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Prasad2004638,\n\tabstract = {Fisher information is a measure of the best precision with which a parameter can be estimated from statistical data. It can also be defined for a continuous random variable without reference to any parameters, in which case it has a physically compelling interpretation of representing the highest precision with which the first cumulant of the random variable, i.e., its mean, can be estimated from its statistical realizations. We construct a complete hierarchy of information measures that determine the best precision with which all of the cumulants of a random variable - and thus its complete probability distribution - can be estimated from its statistical realizations. Several properties of these information measures and their generating functions are discussed.},\n\tart_number = {638-642},\n\tauthor = {Prasad, S. and Menicucci, N.C.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-19 16:35:04 +1100},\n\tdoi = {10.1109/TIT.2004.825034},\n\tjournal = {IEEE Transactions on Information Theory},\n\tnumber = {4},\n\ttitle = {Fisher information with respect to cumulants},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-1942454268&doi=10.1109%2fTIT.2004.825034&partnerID=40&md5=c63aa77abedc12bcdca35049231d1f35},\n\tvolume = {50},\n\tyear = {2004},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-1942454268&doi=10.1109%2fTIT.2004.825034&partnerID=40&md5=c63aa77abedc12bcdca35049231d1f35},\n\tBdsk-Url-2 = {https://doi.org/10.1109/TIT.2004.825034}}\n\n
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\n Fisher information is a measure of the best precision with which a parameter can be estimated from statistical data. It can also be defined for a continuous random variable without reference to any parameters, in which case it has a physically compelling interpretation of representing the highest precision with which the first cumulant of the random variable, i.e., its mean, can be estimated from its statistical realizations. We construct a complete hierarchy of information measures that determine the best precision with which all of the cumulants of a random variable - and thus its complete probability distribution - can be estimated from its statistical realizations. Several properties of these information measures and their generating functions are discussed.\n
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\n  \n 2002\n \n \n (1)\n \n \n
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\n \n\n \n \n \n \n \n \n Local realistic model for the dynamics of bulk-ensemble NMR information processing.\n \n \n \n \n\n\n \n Menicucci, N.; and Caves, C.\n\n\n \n\n\n\n Physical Review Letters, 88(16): 1679011-1679014. 2002.\n \n\n\n\n
\n\n\n\n \n \n \"Local link\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{Menicucci20021679011,\n\tabstract = {The local realistic hidden-variable model was constructed that describes the states and dynamics of bulk-ensemble nuclear magnetic resonance (NMR) information processing up to about 12 nuclear spins. The violation of any Bell-type inequality was ruled out by such model in present NMR experiments. The maximally mixed state was unaffected by the unitary transformation. The NMR experiment determined the expectation value of any product of spin components by applying radio-frequency pulses and then measuring the transverse magnetization of the sample.},\n\tart_number = {167901},\n\tauthor = {Menicucci, N.C. and Caves, C.M.},\n\tdate-added = {2019-03-18 14:39:26 +1100},\n\tdate-modified = {2019-03-18 14:39:26 +1100},\n\tdoi = {10.1103/PhysRevLett.88.167901},\n\tjournal = {Physical Review Letters},\n\tnumber = {16},\n\tpages = {1679011-1679014},\n\ttitle = {Local realistic model for the dynamics of bulk-ensemble NMR information processing},\n\turl_link = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037156909&doi=10.1103%2fPhysRevLett.88.167901&partnerID=40&md5=ba21b5e8b20e6bd8d51c7d165d5d9ce4},\n\tvolume = {88},\n\tyear = {2002},\n\tBdsk-Url-1 = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037156909&doi=10.1103%2fPhysRevLett.88.167901&partnerID=40&md5=ba21b5e8b20e6bd8d51c7d165d5d9ce4},\n\tBdsk-Url-2 = {https://doi.org/10.1103/PhysRevLett.88.167901}}\n\n
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\n The local realistic hidden-variable model was constructed that describes the states and dynamics of bulk-ensemble nuclear magnetic resonance (NMR) information processing up to about 12 nuclear spins. The violation of any Bell-type inequality was ruled out by such model in present NMR experiments. The maximally mixed state was unaffected by the unitary transformation. The NMR experiment determined the expectation value of any product of spin components by applying radio-frequency pulses and then measuring the transverse magnetization of the sample.\n
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