arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2412.14722cond-mat.dis-nncond-mat.mes-hallquant-ph
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随机图中的量子混沌、局域化与相变

Quantum chaos, localization and phase transitions in random graphs

Ioannis Kleftogiannis, Ilias Amanatidis

AI总结:

本文将均匀随机图视为随机紧束缚晶格,发现由边顶点比R表征的随机几何引发量子混沌、局域化及二者间的相变,揭示了随机几何系统具有类似对称性破缺系统的新颖普适相变特性。

摘要:

本文通过将均匀随机图视为随机紧束缚晶格,研究了其能级统计特性。图固有的随机几何结构及其动态空间维度,导致了各种量子混沌和局域化相以及它们之间的相变。本质上,随机几何起到了无序的作用,其强度由图中边与顶点之比R来表征。对于边与顶点之比R较大的稠密图,相邻能级之间的间距遵循Wigner-Dyson分布,导致量子混沌行为和以能级排斥为特征的金属相。当比值接近R=0.5时,图中出现一个巨大的主导连通分量,此时能级间距遵循Poisson分布,伴随能级交叉,并且位于图上的相应波函数呈现局域化相。对于中间比值R,我们观察到了量子混沌相与局域化相之间的相变,该相变由半Poisson分布来表征。发生相变的临界区域的R值取决于系统的能量。我们的分析表明,具有随机几何结构的物理系统(例如具有波动/动态空间维度的系统)包含新颖的普适相变特性,这与基于对称性破缺机制的更传统相变中出现的特性相似,后者的普适性质强烈地由系统的维度决定。

英文摘要:

The energy level statistics of uniform random graphs are studied, by treating the graphs as random tight-binding lattices. The inherent random geometry of the graphs and their dynamical spatial dimensionality, leads to various quantum chaotic and localized phases and transitions between them. Essentially the random geometry acts as disorder, whose strength is characterized by the ratio of edges over vertices R in the graphs. For dense graphs, with large ratio R, the spacing between successive energy levels follows the Wigner-Dyson distribution, leading to a quantum chaotic behavior and a metallic phase, characterized by level repulsion. For ratios near R=0.5, where a large dominating component in the graph appears, the level spacing follows the Poisson distribution with level crossings and a localized phase for the respective wavefunctions lying on the graph. For intermediate ratios R we observe a phase transition between the quantum chaotic and localized phases characterized by a semi-Poisson distribution. The values R of the critical regime where the phase transition occurs depend on the energy of the system. Our analysis shows that physical systems with random geometry, for example ones with a fluctuating/dynamical spatial dimension, contain novel universal phase transition properties, similar to those occuring in more traditional phase transitions based on symmetry breaking mechanisms, whose universal properties are strongly determined by the dimensionality of the system.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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