Extended nonergodic regime and spin subdiffusion in disordered SU(2)-symmetric Floquet systems

Journal Article · Mon Dec 14 00:00:00 EST 2020 · Physical Review. B

DOI:https://doi.org/10.1103/physrevb.102.214205· OSTI ID:1852779

Yang, Zhi-Cheng ^[1]; Nicholls, Stuart ^[2]; Cheng, Meng ^[2]

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1. Univ. of Maryland, College Park, MD (United States); OSTI
2. Yale Univ., New Haven, CT (United States)

In this work, we explore thermalization and quantum dynamics in a one-dimensional disordered SU(2)-symmetric Floquet model, where a many-body localized phase is prohibited by the non-Abelian symmetry. Despite the absence of localization, we find an extended nonergodic regime at strong disorder where the system exhibits nonthermal behaviors. In the strong disorder regime, the level spacing statistics exhibit neither a Wigner-Dyson nor a Poisson distribution, and the spectral form factor does not show a linear-in-time growth at early times characteristic of random matrix theory. The average entanglement entropy of the Floquet eigenstates is subthermal, although violating an area-law scaling with system sizes. We further compute the expectation value of local observables and find strong deviations from the eigenstate thermalization hypothesis. The infinite-temperature spin autocorrelation function decays at long times as $$t^{–β}$$ with $$\textit{β}$$ < 0.5, indicating subdiffusive transport at strong disorders.

• Research Organization: Duke Univ., Durham, NC (United States); Univ. of Maryland, College Park, MD (United States)
• Sponsoring Organization: Alfred P. Sloan Foundation; National Science Foundation (NSF); Simons Foundation; US Air Force Office of Scientific Research (AFOSR); US Army Research Laboratory (USARL); US Army Research Office (ARO); US Department of the Navy, Office of Naval Research (ONR); USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR)
• Grant/Contract Number: SC0019040; SC0019449; SC0020312
• OSTI ID: 1852779
• Journal Information: Physical Review. B, Journal Name: Physical Review. B Journal Issue: 21 Vol. 102; ISSN 2469-9950
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
Materials Science
Physics