Thermalization and Heating Dynamics in Open Generic Many-Body Systems

The last decade has witnessed remarkable progress in understanding of thermalization in isolated quantum systems. Combining the ideas of the eigenstate thermalization hypothesis and 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 for any realization of measurement outcomes. We show that the nonunitary nature of quantum measurement causes several unique thermalization mechanisms that are unseen in isolated systems. We present numerical evidence of our findings by applying our theory to specific models that can be experimentally realized by quantum gas microscopy and in atom-cavity systems. Our theory also provides a general and efficient way to determine an effective temperature of many-body systems subject to the Lindblad master equation and thus should be applicable to noisy dynamics or dissipative systems coupled to nonthermal environments as well as continuously monitored systems. Our work provides yet another insight into why thermodynamics emerges so universally.