Experimental verification of a modified fluctuation-dissipation relation for a micron-sized particle in a non-equilibrium steady state

TL;DR

This paper experimentally verifies a modified fluctuation-dissipation relation for a colloidal particle in a non-equilibrium steady state, demonstrating an equilibrium-like behavior in a driven microscopic system.

Contribution

It provides the first experimental validation of the modified fluctuation-dissipation theorem in a non-equilibrium steady state for a colloidal particle.

Findings

MFDT is perfectly verified by experimental data.

The relation acts as an equilibrium-like fluctuation-dissipation relation in the Lagrangian frame.

The study demonstrates the applicability of MFDT in driven microscopic systems.

Abstract

A modified fluctuation-dissipation-theorem (MFDT) for a non-equilibrium steady state (NESS) is experimentally checked by studying the position fluctuations of a colloidal particle whose motion is confined in a toroidal optical trap. The NESS is generated by means of a rotating laser beam which exerts on the particle a sinusoidal conservative force plus a constant non-conservative one. The MFDT is shown to be perfectly verified by the experimental data. It can be interpreted as an equilibrium-like fluctuation-dissipation relation in the Lagrangian frame of the mean local velocity of the particle.