Vorticity ratchet

We present a new class of thermal ratchets operating under the action of a symmetry breaking non-Hermitian perturbation which rectifies thermal fluctuations, and driven by an unbiased periodic force. The peculiar non-Hermitian dynamics which follows cause energy transduction from the force to the system in such a way that an average ‘uphill’ particle current is induced. We discuss physical realizations in assemblies of orientable particles, in itinerant oscillator models, and in problems of diffusion in disordered media.