Quantum heat engines and nonequilibrium temperature

TL;DR

This paper investigates the concept of an effective temperature in bipartite quantum systems undergoing work extraction, revealing that such systems generally do not equilibrate to a common temperature and introducing a way to characterize their nonequilibrium states.

Contribution

It introduces a definition of effective temperature for nonequilibrium passive states in bipartite quantum systems, expanding understanding of quantum thermodynamics.

Findings

Final states do not reach a common temperature after work extraction.

Effective temperature can characterize nonequilibrium passive states.

Analysis provides insights into quantum thermodynamic processes.

Abstract

A pair of two-level systems initially prepared in different thermal states and coupled to an external reversible work source, do not in general reach a common temperature at the end of a unitary work extraction process. We define an effective temperature for the final nonequilibrium but passive state of the bipartite quantum system and analyse its properties.