Quantum heat machines equivalence and work extraction beyond Markovianity, and strong coupling via heat exchangers

TL;DR

This paper extends the understanding of quantum heat engines by explicitly modeling all components, including non-Markovian effects via heat exchangers, revealing higher degrees of equivalence and novel work extraction capabilities.

Contribution

It introduces a comprehensive model of quantum heat engines with explicit baths and batteries, demonstrating enhanced equivalence and work extraction beyond Markovian assumptions.

Findings

Higher degree of engine equivalence beyond Markovian regime

Conditions for zero entropy increase in work repositories

Possibility of charging batteries while reducing entropy in strong coupling

Abstract

Various engine types are thermodynamically equivalent in the quantum limit of small 'engine action'. Our previous derivation of the equivalence is restricted to Markovian heat baths and to implicit classical work repository (e.g., laser light in the semi-classical approximation). In this paper all the components, baths, batteries, and engine, are explicitly taken into account. To neatly treat non-Markovian dynamics we use mediating particles that function as a heat exchanger. We find that on top of the previously observed equivalence there is a higher degree of equivalence that cannot be achieved in the Markovian regime. Next we focus on the energy transfer to the work repository. A condition for zero entropy increase in the work repository is given. Moreover, it is shown that in the strong coupling regime it is possible to charge a battery with energy while reducing its entropy at the same time.