Quantum thermodynamics for a model of an expanding universe

TL;DR

This paper explores the thermodynamics of quantum fields in an expanding universe, using non-equilibrium fluctuation relations to interpret particle production as an entropic process, offering new insights into quantum cosmology.

Contribution

It introduces a novel application of fluctuation theorems to quantum fields in curved spacetime, linking particle production to entropy increase without assuming traditional entropy-quantum matter relations.

Findings

Particle production interpreted as entropic increase.

Application of fluctuation theorems to curved spacetime.

New perspective on quantum thermodynamics in cosmology.

Abstract

We investigate the thermodynamical properties of quantum fields in curved spacetime. Our approach is to consider quantum fields in curved spacetime as a quantum system undergoing an out-of-equilibrium transformation. The non-equilibrium features are studied by using a formalism which has been developed to derive fluctuation relations and emergent irreversible features beyond the linear response regime. We apply these ideas to an expanding universe scenario, therefore avoiding assumptions on the relation between entropy and quantum matter. We provide a fluctuation theorem which allows us to understand particle production due to the expansion of the universe as an entropic increase. Our results pave the way towards a different understanding of the thermodynamics of relativistic and quantum systems in our universe.