Many-body resonances in the avalanche instability of many-body localization

TL;DR

This paper investigates how many-body resonances facilitate the avalanche instability that causes thermalization in many-body localized systems, revealing a detailed connection between resonances and the spreading of thermalization.

Contribution

It demonstrates that avalanches in MBL systems primarily spread through strong many-body resonances, providing a detailed understanding of the instability mechanism.

Findings

Avalanches spread mainly via strong many-body resonances.

Resonances enable the thermalization process in MBL systems.

Numerical modeling links resonances to avalanche dynamics.

Abstract

Many-body localized (MBL) systems fail to reach thermal equilibrium under their own dynamics, even though they are interacting, nonintegrable, and in an extensively excited state. One instability towards thermalization of MBL systems is the so-called ``avalanche'', where a locally thermalizing rare region is able to spread thermalization through the full system. The spreading of the avalanche may be modeled and numerically studied in finite one-dimensional MBL systems by weakly coupling an infinite-temperature bath to one end of the system. We find that the avalanche spreads primarily via strong many-body resonances between rare near-resonant eigenstates of the closed system. Thus we find and explore a detailed connection between many-body resonances and avalanches in MBL systems.