Driven Soft Matter: Entropy Production and the Fluctuation-Dissipation Theorem

TL;DR

This paper explores the relationship between entropy production and the fluctuation-dissipation theorem in soft matter systems driven beyond equilibrium, using stochastic thermodynamics to connect theoretical concepts with practical examples.

Contribution

It provides a unified framework linking entropy production to fluctuation-dissipation theorem violations in nonequilibrium soft matter systems, with illustrative examples.

Findings

Fluctuation-dissipation theorem breaks down beyond linear response.

Nonzero entropy production characterizes nonequilibrium steady states.

The excess fluctuation-dissipation relation correlates with total entropy production.

Abstract

Entropy and the fluctuation-dissipation theorem are at the heart of statistical mechanics near equilibrium. Driving a system beyond the linear response regime leads to (i) the breakdown of the fluctuation-dissipation theorem and (ii) a nonzero entropy production rate. We show how both phenomena are related using the general framework of stochastic thermodynamics suitable for soft matter systems governed by stochastic dynamics and driven through nonconservative forces or external flows. In particular, the excess of the fluctuation-dissipation theorem in a nonequilibrium steady state compared to equilibrium is related to total entropy production. Alternative recent derivations of generalized fluctuation-dissipation theorems are sketched and related to each other. The theory is illustrated for two systems: a driven single colloidal particle and systems driven through simple shear flow.