Friction and noise for a probe in a nonequilibrium fluid

TL;DR

This paper analyzes the fluctuation dynamics of a probe in a nonequilibrium fluid, deriving extended fluctuation-dissipation relations based on linear response theory in driven particle systems.

Contribution

It introduces a linear response framework to derive friction and noise expressions for a probe in a nonequilibrium medium, extending the second fluctuation-dissipation relation.

Findings

Derived explicit formulas for probe friction and noise in nonequilibrium conditions.

Extended the fluctuation-dissipation relation to nonequilibrium fluids.

Provided a theoretical basis for understanding probe dynamics in driven systems.

Abstract

We investigate the fluctuation dynamics of a probe around a deterministic motion induced by interactions with driven particles. The latter constitute the nonequilibrium medium in which the probe is immersed and is modelled as overdamped Langevin particle dynamics driven by nonconservative forces. The expansion that yields the friction and noise expressions for the reduced probe dynamics is based on linear response around a time dependent nonequilibrium condition of the medium. The result contains an extension of the second fluctuation dissipation relation between friction and noise for probe motion in a nonequilibrium fluid