Realising a quantum absorption refrigerator with an atom-cavity system

TL;DR

This paper proposes and analyzes an autonomous quantum thermal machine using an atom-cavity system, demonstrating potential for ground-state cooling of ions with sunlight and connecting quantum refrigerators to sideband cooling.

Contribution

It introduces a practical implementation of a quantum absorption refrigerator with atom-cavity systems and links it to existing cooling techniques, highlighting experimental feasibility.

Findings

Possible to cool ions near their motional ground state using sunlight

A laser is needed to stabilize cavity frequencies in the setup

Establishes a connection between quantum absorption refrigerators and sideband cooling

Abstract

An autonomous quantum thermal machine comprising a trapped atom or ion placed inside an optical cavity is proposed and analysed. Such a machine can operate as a heat engine whose working medium is the quantised atomic motion, or as an absorption refrigerator which cools without any work input. Focusing on the refrigerator mode, we predict that it is possible with state-of-the-art technology to cool a trapped ion almost to its motional ground state using a thermal light source such as sunlight. We nonetheless find that a laser or similar reference system is necessary to stabilise the cavity frequencies. Furthermore, we establish a direct and heretofore unacknowledged connection between the abstract theory of quantum absorption refrigerators and practical sideband cooling techniques. We also highlight and clarify some assumptions underlying several recent theoretical studies on self-contained quantum engines and refrigerators. Our work indicates that cavity quantum electrodynamics is a promising and versatile experimental platform for the study of autonomous thermal machines in the quantum domain.