Steady-state fluctuation relations for systems driven by an external random force

Université de Lyon, Laboratoire de Physique, Ecole Normale Supérieure de Lyon, CNRS - 46, Allée d'Italie, 69364 Lyon Cedex 07, France, EU

Corresponding author: juan.gomez_solano@ens-lyon.fr

Received: 8 December 2009
Accepted: 10 March 2010

Abstract

We experimentally study the fluctuations of the work done by an external Gaussian random force on two different stochastic systems coupled to a thermal bath: a colloidal particle in an optical trap and an atomic-force microscopy cantilever. We determine the corresponding probability density functions for different random forcing amplitudes ranging from a small fraction to several times the amplitude of the thermal noise. In both systems for sufficiently weak forcing amplitudes the work fluctuations satisfy the usual steady-state fluctuation theorem. As the forcing amplitude drives the system far from equilibrium, deviations of the fluctuation theorem increase monotonically. The deviations can be recasted to a single master curve which only depends on the kind of stochastic external force.