Thermalization via three-wave mixing

TL;DR

This paper demonstrates that three-wave mixing in a multimode quantum cavity can induce thermalization into a Bose-Einstein distribution, challenging the notion that quadratic couplings alone prevent thermalization in isolated systems.

Contribution

It reveals that three-wave perturbations can cause thermalization in quantum cavities, providing a new mechanism for thermalization in solid-state systems.

Findings

Three-wave mixing leads to thermalization into Bose-Einstein distribution.

Thermal state temperature is set by energy conservation.

Thermalization is robust against weak disturbances.

Abstract

We discuss thermalization in a multimode quantum cavity under unitary evolution. According to general principles, an isolated system with quadratic couplings does not exhibit thermalization. However, we find that three-wave perturbation, typical for instance in superconducting Josephson systems, may lead to thermalization into a Bose-Einstein distribution of occupations of the modes. The temperature of this state is dictated by energy conservation in this closed system, and the thermal distribution is robust against weak disturbances. We discuss how our findings open up new avenues to experimentally probe fundamental assumptions of statistical physics in solid-state systems.