Driven probe under harmonic confinement in a colloidal bath

Abstract

Colloids held by optical or magnetic tweezers have been used to explore the local rheological properties of a complex medium and to extract work from fluctuations with some appropriate protocols. However, a general theoretical understanding of the interplay between the confinement and the interaction with the environment is still lacking. Here, we explore the statistical properties of the position of a probe confined in a harmonic trap moving at constant velocity and interacting with a bath of colloidal particles maintained at a different temperature. Interactions among particles are accounted for by a systematic perturbation, whose range of validity is tested against direct simulations of the full dynamics. Overall, our results provide a way to predict the effect of the driving and the environment on the probe, and can potentially be used to investigate the properties of colloidal heat engines with many-body interactions.