Small Systems Warm up Faster Than They Cool Down*

According to the celebrated laws of linear irreversible thermodynamics the rate of relaxation of an extensive thermodynamic observable to its equilibrium value depends linearly on the magnitude of the departure from equilibrium, and is independent of the direction of the departure. However, these laws rely on the assumption of 'local thermodynamic equilibrium' which is expected to break down for small systems quenched far from equilibrium.

It turns out that the relaxation of nano-scale systems driven out of equilibrium by a rapid change in temperature depends also on the direction of the departure from equilibrium. If we consider a pair of thermodynamically equidistant temperature quenches nano-scale systems, contrary to intuition, in fact warm up faster than they cool down. In the talk we will explain the physical origin of this intriguing asymmetry in relaxation to equilibrium and discuss its implications, e.g. for the performance of Brownian heat engines.

Reference: Alessio Lapolla & Aljaz Godec, Phys. Rev. Lett. 125, 110602 (2020).