Autonomous quantum heat engine

TL;DR

This paper reports the first experimental realization of an autonomous quantum heat engine using superconducting circuits, demonstrating heat-driven coherent microwave power generation and validating theoretical models.

Contribution

It introduces an autonomous quantum heat engine in superconducting circuits, operating without external driving, and confirms theoretical predictions through experimental observation.

Findings

Coherent microwave power generated from thermal reservoirs

Validation of theoretical models for autonomous quantum heat engines

Potential for studying quantum effects in thermodynamics

Abstract

Quantum heat engines provide attractive means in quantum thermodynamics for studying the fundamentals of the flow of heat and work. Previous experimental implementations of heat engines operating at the level of a few excitation quanta have utilized external driving, which has made the observation of the produced work challenging. Conversely, autonomous quantum heat engines only require a flow of heat to operate and generate work. However, autonomous quantum heat engines have not yet been experimentally demonstrated in any system despite numerous theoretical investigations. Here, we experimentally realize an autonomous quantum heat engine based on superconducting circuits. We construct the engine circuit implementing an approximate Otto cycle by coupling two superconducting resonators with a superconducting quantum interference device, and coupling this system to spectrally filtered hot and cold reservoirs. By varying the experimental conditions, we observe coherent microwave power generation arising from the internal dynamics of the system driven only by the thermal reservoirs. Our results validate previous theoretical predictions for this circuit and pave the way for detailed studies of quantum effects in heat engines and for using heat-generated coherent microwaves in circuit quantum electrodynamics.