Performance of the collective three-level quantum thermal engine

TL;DR

This paper compares the performance of collective and independent three-level quantum heat engines, revealing that cooperative Lambda-type systems can outperform V-type systems under certain conditions due to enhanced cooperativity effects.

Contribution

It demonstrates that cooperativity significantly improves the performance of Lambda-type quantum heat engines, a novel insight into collective quantum thermal machine efficiency.

Findings

Lambda-type engines can outperform V-type engines with cooperativity.

Cooperativity enhances performance more in Lambda-type systems.

Population inversion and off-diagonal elements differ between V and Lambda types.

Abstract

We investigate the performance of a microscopic quantum heat engine consisting of V- or Lambda-type emitters interacting collectively or independently when being in contact with environmental thermal reservoirs. Though the efficiency of a Carnot's cycle is always higher than those associated with these setups, we have found that the performance of the cooperative Lambda-type heat engine may be larger than that of the V-type under similar conditions. Cooperativity among the emitters plays an important role for the Lambda-type setup, significantly improving its performance, while is less relevant for a V-type thermal engine. This is because the population inversion on the working atomic transition as well as its off-diagonal elements behave differently for these two atomic ensembles.