Extended nonergodic states in disordered many-body quantum systems

TL;DR

This paper provides evidence for extended nonergodic states existing between chaotic and localized phases in disordered many-body quantum systems, using static and dynamic analyses of a finite 1D model.

Contribution

It demonstrates the presence of extended nonergodic states in the intermediate regime, supported by detailed spectral and dynamical property analysis.

Findings

Identification of extended nonergodic states in the intermediate phase

Sensitivity of long-time dynamics to spectral and eigenstate structures

Distinction between chaotic and intermediate regimes via entropy measures

Abstract

This work supports the existence of extended nonergodic states in the intermediate region between the chaotic (thermal) and the many-body localized phases. These states are identified through an extensive analysis of static and dynamical properties of a finite one-dimensional system with onsite random disorder. The long-time dynamics is particularly sensitive to changes in the spectrum and in the structures of the eigenstates. The study of the evolution of the survival probability, Shannon information entropy, and von Neumann entanglement entropy enables the distinction between the chaotic and the intermediate region.