Internal dissipation and heat leaks in quantum thermodynamic cycles

TL;DR

This paper introduces a minimal model for quantum absorption chillers, analyzing irreversibility sources like heat leaks and internal dissipation, and proposes reservoir engineering to improve efficiency.

Contribution

It provides a simplified framework to identify and mitigate irreversibility in quantum heat devices, aiding design of more efficient quantum thermodynamic cycles.

Findings

Identified heat leaks and internal dissipation as key irreversibility sources.

Proposed reservoir engineering techniques to reduce irreversibility.

Applied model to a three-qubit system to analyze practical implications.

Abstract

The direction of the steady-state heat currents across a generic quantum system connected to multiple baths may be engineered so as to realize virtually any thermodynamic cycle. In spite of their versatility such continuous energy-conversion systems are generally unable to operate at maximum efficiency due to non-negligible sources of irreversible entropy production. In this paper we introduce a minimal model of irreversible absorption chiller. We identify and characterize the different mechanisms responsible for its irreversibility, namely heat leaks and internal dissipation, and gauge their relative impact in the overall cooling performance. We also propose reservoir engineering techniques to minimize these detrimental effects. Finally, by looking into a known three-qubit embodiment of the absorption cooling cycle, we illustrate how our simple model may help to pinpoint the different sources of irreversibility naturally arising in more complex practical heat devices.