# Signatures of many-body localization and metastability by weak perturbation

## TL;DR

This paper explores the complex dynamical behaviors of a disordered quantum ladder system, revealing multiple localization and ergodic phases, metastability, and disorder-free MBL, with insights into finite-size effects and quasi-particle dynamics.

## Contribution

It introduces a quasi-particle framework to explain the coexistence of various dynamical features and identifies a reentrant transition and disorder-free MBL in a simple ladder system.

## Key findings

- Demonstrates a reentrant MBL-ergodic-MBL transition
- Identifies metastability and disorder-free MBL phenomena
- Shows relaxation time scale increases with system size

## Abstract

Nonequilibrium dynamics in isolated quantum many-body systems displays a number of intriguing features, such as many-body localization (MBL) and prethermalization. Here we investigate a simple ladder system with disorder, in which various distinct dynamical features coexist and interplay. By exact diagonalization, we demonstrate that the system exhibits the signatures of an MBL-ergodic-MBL reentrant transition, metastability, and disorder-free MBL. We give an account of these properties by introducing a quasi-particle picture and interpreting the quasi-vacuum energy fluctuation as an effective disorder on the quasi-particle dynamics. It is speculated that the weak perturbation behavior is a finite-size effect, but its relaxation time scale increases with the system size.