On intermediate statistics across many-body localization transition

TL;DR

This paper investigates the intermediate level statistics during the many-body localization transition, comparing a Pechukas-Yukawa distribution with other models and numerical data to understand spectral properties.

Contribution

It introduces and tests a single-parameter Pechukas-Yukawa distribution for level statistics, showing its effectiveness in describing many-body localization transitions.

Findings

Pechukas-Yukawa distribution compares favorably with $eta$-Gaussian ensemble.

It is slightly less accurate than the two-parameter $eta$-h ansatz.

Numerical data from quantum systems support the distribution's validity.

Abstract

The level statistics in the transition between delocalized and localized {phases of} many body interacting systems is {considered}. We recall the joint probability distribution for eigenvalues resulting from the statistical mechanics for energy level dynamics as introduced by Pechukas and Yukawa. The resulting single parameter analytic distribution is probed numerically {via Monte Carlo method}. The resulting higher order spacing ratios are compared with data coming from different {quantum many body systems}. It is found that this Pechukas-Yukawa distribution compares favorably with {$\beta$--Gaussian ensemble -- a single parameter model of level statistics proposed recently in the context of disordered many-body systems.} {Moreover, the Pechukas-Yukawa distribution is also} only slightly inferior to the two-parameter $\beta$-h ansatz shown {earlier} to reproduce {level statistics of} physical systems remarkably well.