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arXiv · 2002.09447

Quantum Coherence in Ergodic and Many-Body Localized Systems

Sayandip Dhara·Alioscia Hamma·Eduardo R. Mucciolo
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Abstract

Quantum coherence quantifies the amount of superposition a quantum state can have in a given basis. Since there is a difference in the structure of eigenstates of the ergodic and many-body localized systems, we expect them also to differ in terms of their coherences in a given basis. Here, we numerically calculate different measures of quantum coherence in the excited eigenstates of an interacting disordered Hamiltonian as a function of the disorder. We show that quantum coherence can be used as an order parameter to detect the well-studied ergodic to many-body-localized phase transition. We also perform quantum quench studies to distinguish the behavior of coherence in thermalized and localized phases. We then present a protocol to calculate measurement-based localizable coherence to investigate the thermal and many-body localized phases. The protocol allows one to investigate quantum correlations experimentally in a non-destructive way, in contrast to measures that require tracing out a subsystem, which always destroys coherence and correlation.

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Sayandip Dhara, Alioscia Hamma, Eduardo R. Mucciolo. 2020-02-21. Quantum Coherence in Ergodic and Many-Body Localized Systems. https://doi.org/10.1103/physrevb.102.045140

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