Propagation of Many-body Localization in an Anderson Insulator

TL;DR

This paper investigates how many-body localization in an Anderson insulator persists when coupled to a small quantum bath, using perturbative analysis and tensor network simulations to demonstrate the stability and dynamics of the localized phase.

Contribution

It provides a combined perturbative and numerical study showing that an Anderson insulator remains localized even with a single mobile impurity acting as a quantum heat bath.

Findings

Localization remains stable in the strong interaction regime.

The impurity induces non-trivial entanglement dynamics.

A phenomenological model captures the observed dynamics.

Abstract

Many-body localization (MBL) is an example of a dynamical phase of matter that avoids thermalization. While the MBL phase is robust to weak local perturbations, the fate of an MBL system coupled to a thermalizing quantum system that represents a "heat bath" is an open question that is actively investigated theoretically and experimentally. In this work we consider the stability of an Anderson insulator with a finite density of particles interacting with a single mobile impurity -- a small quantum bath. We give perturbative arguments that support the stability of localization in the strong interaction regime. Large scale tensor network simulations of dynamics are employed to corroborate the presence of the localized phase and give quantitative predictions in the thermodynamic limit. We develop a phenomenological description of the dynamics in the strong interaction regime, and demonstrate that the impurity effectively turns the Anderson insulator into an MBL phase, giving rise to non-trivial entanglement dynamics well captured by our phenomenology.