Non-ergodic extended phase of the Quantum Random Energy model

Lara Faoro; Mikhail Feigel'man; Lev Ioffe

doi:10.1016/j.aop.2019.167916

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arXiv · 1812.06016

Non-ergodic extended phase of the Quantum Random Energy model

Lara Faoro·Mikhail Feigel'man·Lev Ioffe

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Abstract

The concept of non-ergodicity in quantum many body systems can be discussed in the context of the wave functions of the many body system or as a property of the dynamical observables, such as time-dependent spin correlators. In the former approach the non-ergodic delocalized states is defined as the one in which the wave functions occupy a volume that scales as a non-trivial power of the full phase space. In this work we study the simplest spin glass model and find that in the delocalized non-ergodic regime the spin-spin correlators decay with the characteristic time that scales as non-trivial power of the full Hilbert space volume. The long time limit of this correlator also scales as a power of the full Hilbert space volume. We identify this phase with the glass phase whilst the many body localized phase corresponds to a 'hyperglass' in which dynamics is practically absent. We discuss the implications of these finding to quantum information problems.

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Lara Faoro, Mikhail Feigel'man, Lev Ioffe. 2018-12-14. Non-ergodic extended phase of the Quantum Random Energy model. https://doi.org/10.1016/j.aop.2019.167916

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