An endoreversible quantum heat engine driven by atomic collisions

TL;DR

This paper demonstrates a controlled endoreversible quantum Otto cycle using Cesium impurities in a Rubidium bath, achieving high efficiency and stability through quantum control and single-atom heat exchange monitoring.

Contribution

It introduces a novel implementation of an endoreversible quantum heat engine with quantum control and single-atom heat exchange measurement.

Findings

Achieved high efficiency and large power output.

Reduced power fluctuations for stable operation.

Monitored heat exchange at the single-atom level.

Abstract

Quantum heat engines are subjected to quantum fluctuations related to their discrete energy spectra. Such fluctuations question the reliable operation of quantum engines in the microscopic realm. We here realize an endoreversible quantum Otto cycle in the large quasi-spin states of Cesium impurities immersed in an ultracold Rubidium bath. Endoreversible machines are internally reversible and irreversible losses only occur via thermal contact. We employ quantum control over both machine and bath to suppress internal dissipation and regulate the direction of heat transfer that occurs via inelastic spin-exchange collisions. We additionally use full-counting statistics of individual atoms to monitor heat exchange between engine and bath at the level of single quanta, and evaluate average and variance of the power output. We optimize the performance as well as the stability of the quantum engine, achieving high efficiency, large power output and small power output fluctuations.