Fluctuation Theorem for Arbitrary Open Quantum Systems

TL;DR

This paper extends fundamental fluctuation theorems like Crooks and Jarzynski to arbitrary open quantum systems without restrictions on environment or coupling strength, using a free energy concept linked to the Hamiltonian of mean force.

Contribution

It generalizes the fluctuation theorems to open quantum systems with arbitrary environments and coupling, introducing a free energy based on the Hamiltonian of mean force.

Findings

Fluctuation theorems hold for all open quantum systems regardless of environment or coupling.

The free energy used in the theorems relates to the Hamiltonian of mean force.

No restrictions on environment type or coupling strength are needed.

Abstract

Based on the observation that the thermodynamic equilibrium free energy of an open quantum system in contact with a thermal environment can be understood as the difference between the free energy of the total system and that of the bare environment, the validity of the Crooks theorem and of the Jarzynski equality is extended to open quantum systems. No restrictions on the nature of the environment or on the strength of the coupling between system and environment need to be imposed. This free energy entering the Crooks theorem and the Jarzynski equality is closely related to the Hamiltonian of mean force that generalizes the classical statistical mechanical concept of the potential of mean force.