Extending the laws of thermodynamics for arbitrary autonomous quantum systems

TL;DR

This paper generalizes the laws of thermodynamics to arbitrary autonomous quantum systems, providing a framework to understand energy exchanges involving complex quantum sources and their implications for quantum device performance.

Contribution

It extends thermodynamic laws to include arbitrary quantum systems, beyond ideal sources, and analyzes their impact on energy exchanges and quantum machine performance.

Findings

Generalized the second law for arbitrary quantum systems.

Identified work and heat exchanges in complex quantum scenarios.

Illustrated laws with microscopic quantum machines.

Abstract

Originally formulated for macroscopic machines, the laws of thermodynamics were recently shown to hold for quantum systems coupled to ideal sources of work (external classical fields) and heat (systems at equilibrium). Ongoing efforts have been focusing on extending the validity of thermodynamic laws to more realistic, non-ideal energy sources. Here, we go beyond these extensions and show that energy exchanges between arbitrary quantum systems are structured by the laws of thermodynamics. We first generalize the second law and identify the associated work and heat exchanges. After recovering known results from ideal work and heat sources, we analyze some consequences of hybrid work and heat sources. We illustrate our general laws with microscopic machines realizing thermodynamic tasks in which the roles of heat and work sources are simultaneously played by elementary quantum systems. Our results open perspectives to understand and optimize the energetic performances of realistic quantum devices, at any scale.