Energy flow between two hydrodynamically coupled particles kept at different effective temperatures

Flux d'énergie entre deux micro-particules piégées à des températures effectives différentes et interagissant par couplage hydrodynamique

Antoine Bérut (1) , Artyom Petrosyan (1) , Sergio Ciliberto (1)

1 Phys-ENS - Laboratoire de Physique de l'ENS Lyon

We measure the energy exchanged between two hydrodynamically coupled micron-sized Brownian particles trapped in water by two optical tweezers. The system is driven out of equilibrium by random forcing the position of one of the two particles. The forced particle behaves as it has an "effective temperature'' higher than that of the other bead. This driving modifies the equilibrium variances and cross-correlation functions of the bead positions: we measure an energy flow between the particles and an instantaneous cross-correlation, proportional to the effective temperature difference between the two particles. A model of the interaction which is based on classical hydrodynamic coupling tensors is proposed. The theoretical and experimental results are in excellent agreement.

Mots clés: Brownian motion; optical tweezers; hydrodynamic coupling; heat flux; effective temperature

Domaines: Matière Molle [cond-mat.soft]

Antoine Bérut, Artyom Petrosyan, Sergio Ciliberto. Energy flow between two hydrodynamically coupled particles kept at different effective temperatures. EPL - Europhysics Letters, 2014, 107 (6), pp.60004. ⟨10.1209/0295-5075/107/60004⟩. ⟨hal-01057475v3⟩