Fluctuations in out of equilibrium systems: from theory to experiment

TL;DR

This paper reviews fluctuation theorems in out-of-equilibrium systems, comparing stochastic and chaotic systems, and discusses experimental applications including harmonic oscillators, colloidal particles, and molecular motors.

Contribution

It provides an experimental perspective on fluctuation theorems, highlighting differences between stochastic and chaotic systems and analyzing specific experimental setups.

Findings

Fluctuation theorems apply to stochastic systems with measurable work, heat, and entropy.

Experimental data from harmonic oscillators and colloidal particles support theoretical predictions.

Applications to molecular motors demonstrate practical relevance of fluctuation theorems.

Abstract

We introduce from an experimental point of view the main concepts of fluctuation theorems for work, heat and entropy production in out of equilibrium systems. We will discuss the important difference between the applications of these concepts to stochastic systems and to a second class of systems (chaotic systems) where the fluctuations are induced either by chaotic flows or by fluctuating driving forces. We will mainly analyze the stochastic systems using the measurements performed in two experiments : a) a harmonic oscillator driven out of equilibrium by an external force b) a colloidal particle trapped in a time dependent double well potential. We will rapidly describe some consequences of fluctuation theorems and some useful applications to the analysis of experimental data. As an example the case of a molecular motor will be analyzed in some details. Finally we will discuss the problems related to the applications of fluctuation theorems to chaotic systems.