The Critical Behavior of Quantum Stirling Heat Engine

TL;DR

This paper studies how the critical behavior of a quantum Rabi model as the working substance enhances the efficiency of a Stirling heat engine, approaching Carnot efficiency near the critical point.

Contribution

It demonstrates that quantum criticality can significantly improve Stirling engine efficiency and approaches Carnot efficiency at the critical point.

Findings

Criticality positively affects engine efficiency.

Efficiency approaches Carnot limit near critical point.

Quantum phase transition impacts thermodynamic performance.

Abstract

We investigate the performance of a Stirling cycle with a working substance (WS) modeled as the quantum Rabi model (QRM), exploring the impact of criticality on its efficiency. Our findings indicate that the criticality of the QRM has a positive effect on improving the efficiency of the Stirling cycle. Furthermore, we observe that the Carnot efficiency is asymptotically achievable as the WS parameter approaches the critical point, even when both the temperatures of the cold and hot reservoirs are finite. Additionally, we derive the critical behavior for the efficiency of the Stirling cycle, demonstrating how the efficiency asymptotically approaches the Carnot efficiency as the WS parameter approaches the critical point. Our work deepens the understanding of the impact of criticality on the performance of a Stirling heat engine.