Exact symmetries in the velocity fluctuations of a hot Brownian swimmer

TL;DR

This study experimentally and via simulations verifies fundamental symmetry principles in the velocity fluctuations of a hot Brownian swimmer, revealing steady-state fluctuation theorems and a thermodynamic uncertainty relation.

Contribution

It demonstrates the validity of fluctuation theorems and uncertainty relations for a non-equilibrium active particle, supported by a minimal Markovian model.

Findings

Establishment of scalar and vectorial fluctuation theorems.

Verification of a thermodynamic uncertainty relation.

Development of a Markovian model explaining non-equilibrium physics.

Abstract

Symmetries constrain dynamics. We test this fundamental physical principle, experimentally and by molecular dynamics simulations, for a hot Janus swimmer operating far from thermal equilibrium. Our results establish scalar and vectorial steady-state fluctuation theorems and a thermodynamic uncertainty relation that link the fluctuating particle current to its entropy production at an effective temperature. A Markovian minimal model elucidates the underlying non-equilbrium physics.