Quantum Stirling heat engine with squeezed thermal reservoir

TL;DR

This paper investigates a quantum Stirling heat engine utilizing squeezed thermal reservoirs, deriving formulas for work and efficiency, and demonstrating that squeezing can enhance performance beyond classical limits under certain conditions.

Contribution

It provides analytical expressions for work and efficiency of a quantum Stirling engine with squeezed reservoirs, showing how squeezing improves performance beyond Carnot limits.

Findings

Squeezing increases the effective temperature of the working medium.

Efficiency surpasses the Carnot limit with sufficient squeezing and small temperature ratios.

Performance depends on the nature of the working medium.

Abstract

We analyze the performance of a quantum Stirling heat engine (QSHE), using a two level system and the harmonic oscillator as the working medium, that contacts with a squeezed thermal reservoir and a cold reservoir. First, we derive closed-form expressions for the produced work and efficiency which strongly depends on the squeezing parameter $r_h$. Then, we prove that the effect of squeezing heats the working medium to a higher effective temperature which leads to better overall performance. In particular, the efficiency increases with the degree of squeezing surpassing the standard Carnot limit, when the ratio of temperatures of hot and cold reservoir is small. Furthermore, we derive the analytical expressions for the efficiency at maximum work and the maximum produced work in the high and low temperature regime and we find that at extreme temperatures the squeezing parameter $r_h$ does not affect the performance of the QSHE. Finally, the performance of the QSHE depends on the nature of the working medium.