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arXiv 1702.01622cond-mat.dis-nncond-mat.quant-gascond-mat.stat-mechcond-mat.str-el
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用局域微扰效应表征无序费米子系统的时间不可逆性

Characterizing time-irreversibility in disordered fermionic systems by the effect of local perturbations

Shreya Vardhan, Giuseppe De Tomasi, Markus Heyl, Eric J. Heller, Frank Pollmann

摘要:

为了刻画时间不可逆性,我们研究了局域微扰对无序费米子系统动力学的影响。我们重点讨论了三个不同的系统,非相互作用的Anderson和Aubry-André-Harper(AAH-)模型,以及相互作用的无自旋无序t-V链。首先,我们考虑通过测量Loschirton回波(LE)对全多体波函数的影响。我们表明,在扩展/遍历阶段的LE随时间的指数快速衰减,而在本地化阶段的衰减是代数的。我们表明,指数的本地化阶段的LE的衰减发散成比例的单粒子本地化长度,因为我们接近AAH模型中的金属-绝缘体过渡。其次,我们通过研究由空间局部扰动不同的两个哈密顿量演化的局部观测量的时间期望值来探测无序系统的不同相位。值得注意的是,我们发现,多体局域系统可能会失去记忆的初始状态在长时间的限制,在非相互作用的本地化阶段,一些记忆总是保存。

英文摘要:

We study the effects of local perturbations on the dynamics of disordered fermionic systems in order to characterize time-irreversibility. We focus on three different systems, the non-interacting Anderson and Aubry-André-Harper (AAH-) models, and the interacting spinless disordered t-V chain. First, we consider the effect on the full many-body wave-functions by measuring the Loschmidt echo (LE). We show that in the extended/ergodic phase the LE decays exponentially fast with time, while in the localized phase the decay is algebraic. We demonstrate that the exponent of the decay of the LE in the localized phase diverges proportionally to the single-particle localization length as we approach the metal-insulator transition in the AAH model. Second, we probe different phases of disordered systems by studying the time expectation value of local observables evolved with two Hamiltonians that differ by a spatially local perturbation. Remarkably, we find that many-body localized systems could lose memory of the initial state in the long-time limit, in contrast to the non-interacting localized phase where some memory is always preserved.

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