Terahertz-light quantum tuning of a metastable emergent phase hidden by superconductivity. Yang, X., Vaswani, C., Sundahl, C., Mootz, M., Gagel, P., Luo, L., Kang, J. H., Orth, P. P., Perakis, I. E., Eom, C. B., & Wang, J. NATURE MATERIALS, 17(7):586+, JUL, 2018.
doi  abstract   bibtex   
`Sudden' quantum quench and prethermalization have become a cross-cutting theme for discovering emergent states of matter(1-4). Yet this remains challenging in electron matters(5-9), especially superconductors(10-14). The grand question of what is hidden underneath superconductivity (SC)(15) appears universal, but poorly understood. Here we reveal a long-lived gapless quantum phase of prethermalized quasiparticles (QPs) after a single-cycle terahertz (THz) quench of a Nb3Sn SC gap. Its conductivity spectra is characterized by a sharp coherent peak and a vanishing scattering rate that decreases almost linearly towards zero frequency, which is most pronounced around the full depletion of the condensate and absent for a high-frequency pump. Above a critical pump threshold, such a QP phase with coherent transport and memory persists as an unusual prethermalization plateau, without relaxation to normal and SC thermal states for an order of magnitude longer than the QP recombination and thermalization times. Switching to this metastable `quantum QP fluid' signals non-thermal quench of coupled SC and charge-density-wave (CDW)-like orders and hints quantum control beneath the SC.
@article{ ISI:000436341400011,
Author = {Yang, X. and Vaswani, C. and Sundahl, C. and Mootz, M. and Gagel, P. and
   Luo, L. and Kang, J. H. and Orth, P. P. and Perakis, I. E. and Eom, C.
   B. and Wang, J.},
Title = {{Terahertz-light quantum tuning of a metastable emergent phase hidden by
   superconductivity}},
Journal = {{NATURE MATERIALS}},
Year = {{2018}},
Volume = {{17}},
Number = {{7}},
Pages = {{586+}},
Month = {{JUL}},
Abstract = {{`Sudden' quantum quench and prethermalization have become a
   cross-cutting theme for discovering emergent states of matter(1-4). Yet
   this remains challenging in electron matters(5-9), especially
   superconductors(10-14). The grand question of what is hidden underneath
   superconductivity (SC)(15) appears universal, but poorly understood.
   Here we reveal a long-lived gapless quantum phase of prethermalized
   quasiparticles (QPs) after a single-cycle terahertz (THz) quench of a
   Nb3Sn SC gap. Its conductivity spectra is characterized by a sharp
   coherent peak and a vanishing scattering rate that decreases almost
   linearly towards zero frequency, which is most pronounced around the
   full depletion of the condensate and absent for a high-frequency pump.
   Above a critical pump threshold, such a QP phase with coherent transport
   and memory persists as an unusual prethermalization plateau, without
   relaxation to normal and SC thermal states for an order of magnitude
   longer than the QP recombination and thermalization times. Switching to
   this metastable `quantum QP fluid' signals non-thermal quench of coupled
   SC and charge-density-wave (CDW)-like orders and hints quantum control
   beneath the SC.}},
DOI = {{10.1038/s41563-018-0096-3}},
ISSN = {{1476-1122}},
EISSN = {{1476-4660}},
ResearcherID-Numbers = {{Orth, Peter/A-9408-2013
   }},
ORCID-Numbers = {{Orth, Peter/0000-0003-2183-8120
   Yang, Xu/0000-0002-3856-8182}},
Unique-ID = {{ISI:000436341400011}},
}
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