Quantum entropy thermalization

03/10/2023 10:00 am - 11:00 am

Quantum Matter Seminar

Speaker: Yichen Huang (Harvard)

Title: Quantum entropy thermalization

Abstract: In an isolated quantum many-body system undergoing unitary evolution, the entropy of a subsystem (smaller than half the system size) thermalizes if at long times, it is to leading order equal to the thermodynamic entropy of the subsystem at the same energy. We prove entropy thermalization for a nearly integrable Sachdev-Ye-Kitaev model initialized in a pure product state. The model is obtained by adding random all-to-all 4-body interactions as a perturbation to a random free-fermion model. In this model, there is a regime of “thermalization without eigenstate thermalization.” Thus, the eigenstate thermalization hypothesis is not a necessary condition for thermalization.

References: arXiv:2302.10165, 2209.09826; Joint work with Aram W. Harrow