Surmise for random matrices' level spacing distributions beyond nearest-neighbors

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Autori principali: Shir, Ruth, Martinez-Azcona, Pablo, Chenu, Aurélia
Natura: Preprint
Pubblicazione: 2025
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author Shir, Ruth
Martinez-Azcona, Pablo
Chenu, Aurélia
author_facet Shir, Ruth
Martinez-Azcona, Pablo
Chenu, Aurélia
contents Correlations between energy levels can help distinguish whether a many-body system is of integrable or chaotic nature. The study of short-range and long-range spectral correlations generally involves quantities which are very different, unless one uses the $k$-th nearest neighbor ($k$NN) level spacing distributions. For nearest-neighbor (NN) spectral spacings, the distribution in random matrices is well captured by the Wigner surmise. This well-known approximation, derived exactly for a 2$\times$2 matrix, is simple and satisfactorily describes the NN spacings of larger matrices. There have been attempts in the literature to generalize Wigner's surmise to further away neighbors. However, as we show, the current proposal in the literature fails to accurately capture numerical data. Using the known variance of the distributions from random matrix theory, we propose a corrected surmise for the $k$NN spectral distributions. This surmise better characterizes spectral correlations while retaining the simplicity of Wigner's surmise. We test the predictions against numerical results and show that the corrected surmise is systematically more accurate at capturing data from random matrices. Using the XXZ spin chain with random on-site disorder, we illustrate how these results can be used as a refined probe of many-body quantum chaos for both short- and long-range spectral correlations.
format Preprint
id arxiv_https___arxiv_org_abs_2504_20134
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Surmise for random matrices' level spacing distributions beyond nearest-neighbors
Shir, Ruth
Martinez-Azcona, Pablo
Chenu, Aurélia
Quantum Physics
Disordered Systems and Neural Networks
Statistical Mechanics
Mathematical Physics
Correlations between energy levels can help distinguish whether a many-body system is of integrable or chaotic nature. The study of short-range and long-range spectral correlations generally involves quantities which are very different, unless one uses the $k$-th nearest neighbor ($k$NN) level spacing distributions. For nearest-neighbor (NN) spectral spacings, the distribution in random matrices is well captured by the Wigner surmise. This well-known approximation, derived exactly for a 2$\times$2 matrix, is simple and satisfactorily describes the NN spacings of larger matrices. There have been attempts in the literature to generalize Wigner's surmise to further away neighbors. However, as we show, the current proposal in the literature fails to accurately capture numerical data. Using the known variance of the distributions from random matrix theory, we propose a corrected surmise for the $k$NN spectral distributions. This surmise better characterizes spectral correlations while retaining the simplicity of Wigner's surmise. We test the predictions against numerical results and show that the corrected surmise is systematically more accurate at capturing data from random matrices. Using the XXZ spin chain with random on-site disorder, we illustrate how these results can be used as a refined probe of many-body quantum chaos for both short- and long-range spectral correlations.
title Surmise for random matrices' level spacing distributions beyond nearest-neighbors
topic Quantum Physics
Disordered Systems and Neural Networks
Statistical Mechanics
Mathematical Physics
url https://arxiv.org/abs/2504.20134