Signatures of Many-Body Localization in a Controlled Open Quantum System

TLDR

Disordered interacting quantum systems can exhibit many‑body localization and resist thermalization, but even weak coupling to a thermal environment eventually destroys MBL signatures, posing a challenge for experimental studies because no system can be perfectly isolated. The study experimentally investigates how controlled dissipation drives thermalization in a many‑body localized system, aiming to establish a framework for probing MBL in open systems and extrapolating closed‑system behavior. The experiment uses controlled photon scattering to induce dissipation in a localized system and monitors the resulting dynamics. Photon scattering induces a stretched‑exponential decay of the initial density pattern with a rate linearly proportional to the scattering rate, while susceptibility rises sharply near the phase transition and shows a strong interaction dependence, establishing a foundation for studying MBL in open systems and extrapolating closed‑system properties.

Abstract

In the presence of disorder, an interacting closed quantum system can undergo many-body localization (MBL) and fail to thermalize. However, over long times even weak couplings to any thermal environment will necessarily thermalize the system and erase all signatures of MBL. This presents a challenge for experimental investigations of MBL, since no realistic system can ever be fully closed. In this work, we experimentally explore the thermalization dynamics of a localized system in the presence of controlled dissipation. Specifically, we find that photon scattering results in a stretched exponential decay of an initial density pattern with a rate that depends linearly on the scattering rate. We find that the resulting susceptibility increases significantly close to the phase transition point. In this regime, which is inaccessible to current numerical studies, we also find a strong dependence on interactions. Our work provides a basis for systematic studies of MBL in open systems and opens a route towards extrapolation of closed system properties from experiments.