Floquet-state cooling

TL;DR

This paper shows that periodically driven quantum systems can reach a quasistationary state that is effectively colder than their thermal environment, by selectively populating Floquet states through tailored reservoir interactions.

Contribution

It introduces a mechanism for Floquet-state cooling using a peaked reservoir density of states, enabling control over the system's effective temperature.

Findings

Floquet states can be selectively populated to achieve effective cooling.

The system's Fourier spectrum enables targeted interaction with the reservoir.

Potential applications in driven solid-state systems with phonon baths.

Abstract

We demonstrate that a periodically driven quantum system can adopt a quasistationary state which is effectively much colder than a thermal reservoir it is coupled to, in the sense that certain Floquet states of the driven-dissipative system can carry much higher population than the ground state of the corresponding undriven system in thermal equilibrium. This is made possible by a rich Fourier spectrum of the system's Floquet transition matrix elements, the components of which are addressed individually by a suitably peaked reservoir density of states. The effect is expected to be important for driven solid-state systems interacting with a phonon bath predominantly at well-defined frequencies.