Realization of nonequilibrium thermodynamic processes using external colored noise

TL;DR

This study demonstrates how external colored noise can be used to drive single microparticles out of equilibrium, allowing the observation of fluctuation theorems and informing the design of microscopic motors.

Contribution

It experimentally verifies Crooks fluctuation theorem under external colored noise and introduces a setup for controlling nonequilibrium thermodynamic processes at microscopic scales.

Findings

Fluctuations obey Crooks fluctuation theorem at effective temperature.

External noise amplitude controls particle fluctuation and effective temperature.

Proper sampling and noise cutoff frequencies are crucial for accurate results.

Abstract

We investigate the dynamics of single microparticles immersed in water that are driven out of equilibrium in the presence of an additional external colored noise. As a case study, we trap a single polystyrene particle in water with optical tweezers and apply an external electric field with flat spectrum but a finite bandwidth of the order of kHz. The intensity of the external noise controls the amplitude of the fluctuations of the position of the particle, and therefore of its effective temperature. Here we show, in two different nonequilibrium experiments, that the fluctuations of the work done on the particle obey Crooks fluctuation theorem at the equilibrium effective temperature, given that the sampling frequency and the noise cutoff frequency are properly chosen. Our experimental setup can be therefore used to improve the design of microscopic motors towards fast and efficient devices, thus extending the frontiers of nano machinery.