An Information--Theoretic Equality Implying the Jarzynski Relation

TL;DR

This paper derives a general information-theoretic equality that encompasses the Jarzynski relation, revealing the fundamental connection between information theory and thermodynamics in quantum and classical systems.

Contribution

It introduces a new information-theoretic equality that underpins the Jarzynski relation, bridging thermodynamics and information theory.

Findings

The equality implies non-negativity of mutual information between measurement outcomes.

It contains the Jarzynski relation as a special case.

The result applies to both quantum and classical thermodynamic processes.

Abstract

We derive a general information-theoretic equality for a system undergoing two projective measurements separated by a general temporal evolution. The equality implies the non-negativity of the mutual information between the measurement outcomes of the earlier and later projective measurements. We show that it also contains the Jarzynski relation between the average exponential of the thermodynamical work and the exponential of the difference between the initial and final free energy. Our result elucidates the information-theoretic underpinning of thermodynamics and explains why the Jarzynski relation holds identically both quantumly as well as classically.