Thermalization without detailed balance: population oscillations in the absence of coherences

TL;DR

This paper investigates how open quantum systems that violate detailed balance can exhibit population oscillations during thermalization, revealing novel dynamical transitions and oscillatory regimes driven by temperature effects.

Contribution

It demonstrates that systems breaking microreversibility can still thermalize and exhibit population oscillations without quantum coherences, identifying exceptional points and energy scales involved.

Findings

Population oscillations occur without quantum coherences.

Exceptional points mark sharp transitions in thermalization dynamics.

High temperatures induce oscillatory regimes due to detailed balance violation.

Abstract

Open quantum systems that comply with the master equation and detailed balance decay in a non-oscillatory manner to thermal equilibrium. Beyond the weak coupling limit, systems that break microreversibility (e.g., in the presence of magnetic fields) violate detailed balance but still thermalize. We study the thermalization of these systems and show that a temperature rise produces novel exceptional points that indicate a sharp transition in the thermalization dynamics. A further temperature increase fuels oscillations of the energy level populations even without quantum coherences. Moreover, the violation of detailed balance introduces an energy scale that characterizes the oscillatory regime at high temperatures.