Thermodynamic analysis of autonomous quantum systems

TL;DR

This paper applies a recent autonomous quantum thermodynamic framework to experimental systems, revealing new work exchange mechanisms involving population inversion, coherence, and athermality, beyond traditional heat-based analysis.

Contribution

It demonstrates how the autonomous framework uncovers novel work exchange processes in quantum systems, highlighting limitations of traditional thermodynamics.

Findings

Identifies work mechanisms via population inversion and coherence.

Reveals a non-unitary work exchange related to athermality.

Distinguishes local work from interaction energy in semi-classical limit.

Abstract

Traditional quantum thermodynamic frameworks associate work to energy exchanges induced by unitary transformations generated by external controls, and heat to energy exchanges induced by bath interaction. Recently, a framework was introduced aiming at extending the thermodynamic formalism to genuine quantum settings, also referred to as autonomous quantum systems: free from external controls, only quantum systems interacting with each other. In this paper, we apply such a thermodynamic framework to common experimental situations of interacting quantum systems. In situations where traditional frameworks detect only heat exchanges, the recent autonomous thermodynamic framework points at work exchanges based on two mechanisms: population inversion and coherence generation / consumption. Such mechanisms are well known in the literature for being related to work expenditure and extraction, in particular in relation with ergotropy, which emphasizes the relevance of the autonomous framework and the limitations of traditional ones. Furthermore, the autonomous framework also identifies a genuine non-unitary mechanism of work exchange related to athermality. %, also pointed out as a resource for work extraction. Finally, in the semi-classical limit, the autonomous framework identifies all energy exchanges as pure work, but distinguishes between local work and interaction energy. Our results show that the autonomous framework provides a refined analysis of work exchange mechanisms in the quantum realm and serves as a consistent approach to analyze thermodynamic processes in realistic quantum devices.