ASYMMETRIC MOTION IN A DOUBLE-WELL UNDER THE ACTION OF ZERO-MEAN GAUSSIAN WHITE-NOISE AND PERIODIC FORCING

Residence times of a particle in both of the wells of a double-well sy stem, under the action of zero-mean Gaussian white noise and zero-aver aged but temporally asymmetric periodic forcings, are recorded in a nu merical simulation. The difference between the relative mean residence times in the two wells shows monotonic variation as a function of asy mmetry in the periodic forcing and for a given asymmetry the differenc e becomes largest at an optimum value of the noise strength. Moreover, the passages from one well to the other become less synchronous at sm all noise strengths as the asymmetry parameter (defined below) differs from zero, but at relatively larger noise strengths the passages beco me more synchronous with asymmetry in the field sweep. We propose that asymmetric periodic forcing (with zero mean) could provide a simple b ut sensible physical model for unidirectional motion in a symmetric pe riodic system aided by a symmetric Gaussian white noise.