Vortex ratchet

Abstract

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 a unbiased periodic force. The peculiar non-Hermitian dynamics which follows causes 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.

Contribution to the Proceedings to the meeting `Stochastic Systems: From Randomness to Complexity'. (Erice, Italy, July 2002) to appear in a special issue of Physica A