Detecting topological entanglement entropy in a lattice of quantum harmonic oscillators. Demarie, T.; Linjordet, T.; Menicucci, N.; and Brennen, G. New Journal of Physics, 2014.
Detecting topological entanglement entropy in a lattice of quantum harmonic oscillators [link]Link  doi  abstract   bibtex   
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. o̧pyright 2014 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
@article{Demarie2014,
	abstract = {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.},
	art_number = {085011},
	author = {Demarie, T.F. and Linjordet, T. and Menicucci, N.C. and Brennen, G.K.},
	date-added = {2019-03-18 14:39:26 +1100},
	date-modified = {2019-03-18 14:39:26 +1100},
	doi = {10.1088/1367-2630/16/8/085011},
	journal = {New Journal of Physics},
	title = {Detecting topological entanglement entropy in a lattice of quantum harmonic oscillators},
	url_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},
	volume = {16},
	year = {2014},
	Bdsk-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},
	Bdsk-Url-2 = {https://doi.org/10.1088/1367-2630/16/8/085011}}
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