Asymmetric Quantum Harmonic Otto Engine Under Hot Squeezed Thermal Reservoir

TL;DR

This paper analyzes a quantum harmonic Otto engine operating with a hot squeezed thermal reservoir, exploring how asymmetry and squeezing influence efficiency, work output, and operational regimes through analytic expressions and phase diagrams.

Contribution

It introduces a detailed analysis of asymmetric quantum Otto engines with squeezed reservoirs, deriving efficiency bounds and exploring the impact of squeezing on performance.

Findings

Maximum efficiency approaches 1/2 in sudden expansion case

Efficiency approaches unity in sudden compression case

Operational mode expands with increased squeezing

Abstract

We study a quantum harmonic Otto engine under a hot squeezed thermal reservoir with asymmetry between the two adiabatic branches introduced by considering different speeds of the driving protocols. In the first configuration, the driving protocol for the expansion stroke is sudden-switch in nature and compression stroke is driven adiabatically, while the second configuration deals with the converse situation. In both cases, we obtain analytic expressions for the upper bound on efficiency and efficiency at optimal work output, which reveals a significant difference between the two configurations. Additionally, we find that the maximum achievable efficiency in sudden expansion case is 1/2 only while it approaches unity for the sudden compression stroke. Further, we study the effect of increasing degree of squeezing on the efficiency and work output of the engine and indicate the optimal operational regime for both configurations under consideration. Finally, by studying the full phase-diagram of the Otto cycle we observe that the operational region of the engine mode grows with increasing squeezing at the expense of refrigeration regime.