Total correlations of the diagonal ensemble as a generic indicator for ergodicity breaking in quantum systems

Article

关键词: MANY-BODY LOCALIZATION;    QUANTIZED CHAOTIC SYSTEMS;    STATISTICAL-MECHANICS;    THERMALIZATION;    ENTANGLEMENT;    EQUILIBRIUM;    DYNAMICS;    LATTICES;    ENTROPY;    STATES;   

DOI  :  10.1103/PhysRevB.95.125118

来源: SCIE

【 摘 要 】

The diagonal ensemble is the infinite time average of a quantum state following unitary dynamics in systems without degeneracies. In analogy to the time average of a classical phase-space dynamics, it is intimately related to the ergodic properties of the quantum system giving information on the spreading of the initial state in the eigenstates of the Hamiltonian. In this work we apply a concept from quantum information, known as total correlations, to the diagonal ensemble. Forming an upper bound on the multipartite entanglement, it quantifies the combination of both classical and quantum correlations in a mixed state. We generalize the total correlations of the diagonal ensemble to more general alpha- Renyi entropies and focus on the cases alpha = 1 and alpha = 2 with further numerical extensions in mind. Here we show that the total correlations of the diagonal ensemble is a generic indicator of ergodicity breaking, displaying a subextensive behavior when the system is ergodic. We demonstrate this by investigating its scaling in a range of spin chain models focusing not only on the cases of integrability breaking but also emphasize its role in understanding the transition from an ergodic to a many-body localized phase in systems with disorder or quasiperiodicity.

【 授权许可】

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