Entropy production and work fluctuation relations for a single particle in active bath

TL;DR

This paper investigates entropy production and work fluctuation relations for a colloidal particle in an active bath, modeled as an overdamped harmonic oscillator with thermal and active noise, revealing modified fluctuation relations in non-equilibrium steady states.

Contribution

It introduces an effective temperature framework for active baths and derives modified fluctuation relations for entropy and work in such non-equilibrium conditions.

Findings

Effective temperature describes the steady state of active bath systems.

Conventional transient fluctuation theorem for work does not hold in active baths.

A steady state fluctuation relation for work with a renormalized temperature is established.

Abstract

A colloidal particle immersed in a bath of bacteria is a typical example of a passive particle in an active bath. To model this, we take an overdamped harmonically trapped particle subjected to a thermal and a non-equilibrium noise arising from the active bath. The harmonic well can be attributed to a laser trap or to the small amplitude motion of the sedimented colloid at the bottom of the capillary. In the long time, the system reaches a non-equilibrium steady state that can be described by an effective temperature. By adopting this notion of effective temperature, we investigate whether fluctuation relations for entropy hold. In addition, when subjected to a deterministic time dependent drag, we find that transient fluctuation theorem for work cannot be applied in conventional form. However, a steady state fluctuation relation for work emerges out with a renormalized temperature.