arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1508.07293cond-mat.dis-nncond-mat.stat-mechquant-ph
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多体局域化跃迁的谱统计

Spectral statistics across the many-body localization transition

Maksym Serbyn, Joel E. Moore

摘要:

无序相互作用系统中各态历经相与多体定域相之间的多体局域化相变是近年来研究的热点。本征能的统计被认为是一个强有力的探针之间的交叉遍历和可积系统在量子混沌的简单例子。我们考虑的频谱统计的演变在MBLT,从映射到一个布朗运动过程,分析相关的频谱特性的矩阵元素的统计。我们证明了从Wigner-Dyson到Poisson统计的流动是一个两阶段的过程。首先,分形增强的矩阵元素接近MBLT从金属侧产生有效的幂律之间的相互作用的能级,并导致等离子体模型的水平统计。在第二阶段,气体的本征值有本地的相互作用和水平统计属于一个半泊松普适类。我们验证了我们的研究结果数值上的XXZ自旋链。我们提供了一个微观的理解水平统计的MBLT和讨论的过渡,可能的理论是强有力的约束的影响。

英文摘要:

The many-body localization transition (MBLT) between ergodic and many-body localized phase in disordered interacting systems is a subject of much recent interest. Statistics of eigenenergies is known to be a powerful probe of crossovers between ergodic and integrable systems in simpler examples of quantum chaos. We consider the evolution of the spectral statistics across the MBLT, starting with mapping to a Brownian motion process that analytically relates the spectral properties to the statistics of matrix elements. We demonstrate that the flow from Wigner-Dyson to Poisson statistics is a two-stage process. First, fractal enhancement of matrix elements upon approaching the MBLT from the metallic side produces an effective power-law interaction between energy levels, and leads to a plasma model for level statistics. At the second stage, the gas of eigenvalues has local interaction and level statistics belongs to a semi-Poisson universality class. We verify our findings numerically on the XXZ spin chain. We provide a microscopic understanding of the level statistics across the MBLT and discuss implications for the transition that are strong constraints on possible theories.

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