Thermodynamic fluctuations in actively cooled resonators
We analyze the heat and work fluctuations in a macroscopic electromechanical oscillator in contact with a thermostat and cooled by an active feedback system. The oscillator is observed in a nonequilibrium steady state caused by a stochastic driving, implemented through an electronic feedback cooling. The experimentally measured fluctuations are in excellent agreement with theoretical predictions based on a Langevin model, whose driving term is stochastic and equivalent to a viscous force. The fluctuations of the heat absorbed by the bath are asymmetric as expected for nonequilibrium steady states.