Phenomenology of many-body localization in bond-disordered spin chains

TL;DR

This paper investigates many-body localization in bond-disordered spin chains, revealing characteristic entanglement and spectral features, and proposing a real space renormalization approach to understand the breakdown of thermalization.

Contribution

It introduces a novel analysis of MBL in bond-disordered systems, highlighting phenomenological features beyond local integrals of motion and suggesting experimental probing methods.

Findings

Multimodal entanglement entropy distribution in eigenstates

Sub-Poissonian level statistics observed

Relation between operators, initial states, and thermalization breakdown

Abstract

Many-body localization (MBL) hinders the thermalization of quantum many-body systems in the presence of strong disorder. In this work, we study the MBL regime in bond-disordered spin-1/2 XXZ spin chain, finding the multimodal distribution of entanglement entropy in eigenstates, sub-Poissonian level statistics, and revealing a relation between operators and initial states required for examining the breakdown of thermalization in the time evolution of the system. We employ a real space renormalization group scheme to identify these phenomenological features of the MBL regime that extend beyond the standard picture of local integrals of motion relevant for systems with disorder coupled to on-site operators. Our results pave the way for experimental probing of MBL in bond-disordered spin chains.