Influence of rotational force fields on the determination of the work done on a driven Brownian particle

TL;DR

This paper investigates how nonconservative rotational radiation forces affect the measurement of work distributions in driven Brownian particles, revealing that these forces increase with particle refractive index and influence thermodynamic measurements.

Contribution

It demonstrates experimentally that rotational radiation forces significantly impact work distribution measurements in colloidal systems, highlighting the importance of nonconservative forces in stochastic thermodynamics.

Findings

Rotational radiation forces increase with particle refractive index.

Work distribution measurements are influenced by nonconservative forces.

Experimental evidence shows the impact of rotational forces on thermodynamic quantities.

Abstract

For a Brownian system the evolution of thermodynamic quantities is a stochastic process. In particular, the work performed on a driven colloidal particle held in an optical trap changes for each realization of the experimental manipulation, even though the manipulation protocol remains unchanged. Nevertheless, the work distribution is governed by established laws. Here, we show how the measurement of the work distribution is influenced by the presence of rotational, i.e. nonconservative, radiation forces. Experiments on particles of different materials show that the rotational radiation forces, and therefore their effect on the work distributions, increase with the particle refractive index.