Probing entanglement in a many-body-localized system

TL;DR

This study experimentally investigates many-body localization in a disordered Bose-Hubbard chain, revealing entanglement growth and localization effects that distinguish it from non-interacting systems, advancing understanding of quantum thermalization breakdown.

Contribution

First experimental measurement of entanglement properties in a many-body-localized Bose-Hubbard system using particle fluctuations and correlations.

Findings

Particles become localized, suppressing transport.

Non-local correlations develop with logarithmic entanglement growth.

Many-body localization is distinct from non-interacting localization.

Abstract

An interacting quantum system that is subject to disorder may cease to thermalize due to localization of its constituents, thereby marking the breakdown of thermodynamics. The key to our understanding of this phenomenon lies in the system's entanglement, which is experimentally challenging to measure. We realize such a many-body-localized system in a disordered Bose-Hubbard chain and characterize its entanglement properties through particle fluctuations and correlations. We observe that the particles become localized, suppressing transport and preventing the thermalization of subsystems. Notably, we measure the development of non-local correlations, whose evolution is consistent with a logarithmic growth of entanglement entropy - the hallmark of many-body localization. Our work experimentally establishes many-body localization as a qualitatively distinct phenomenon from localization in non-interacting, disordered systems.