Thermalization and Heating Dynamics in Open Generic Many-Body Systems

TL;DR

This paper extends quantum thermalization theory to open many-body systems under continuous observation, revealing unique thermalization mechanisms caused by measurement and providing methods to determine effective temperatures in dissipative quantum systems.

Contribution

It introduces a framework combining eigenstate thermalization with measurement theory, showing thermalization at the trajectory level in open systems and offering a way to compute effective temperatures.

Findings

Open many-body systems thermalize under continuous measurement.

Measurement induces unique thermalization mechanisms not seen in isolated systems.

Numerical models demonstrate the theory's applicability to experimental setups.

Abstract

The last decade has witnessed the remarkable progress in our understanding of thermalization in isolated quantum systems. Combining the eigenstate thermalization hypothesis with quantum measurement theory, we extend the framework of quantum thermalization to open many-body systems. A generic many-body system subject to continuous observation is shown to thermalize at a single trajectory level. We show that the nonunitary nature of quantum measurement causes several unique thermalization mechanisms that are unseen in isolated systems. We present numerical evidence for our findings by applying our theory to specific models that can be experimentally realized in atom-cavity systems and with quantum gas microscopy. Our theory provides a general method to determine an effective temperature of quantum many-body systems subject to the Lindblad master equation and thus should be applicable to noisy dynamics or dissipative systems coupled to nonthermal Markovian environments as well as continuously monitored systems. Our work provides yet another insight into why thermodynamics emerges so universally.