SUPPRESSION OF DETERMINISTIC DIFFUSION BY NOISE

A one-dimensional discrete-time dynamics near the onset of determinist ic diffusion additively coupled to weak Gaussian white noise is studie d. The diffusion coefficient is related to the escape rate out of an i nterval and a method for the calculation of this rate is introduced wh ich, unlike previous investigations, fully takes into account all rele vant escape paths. It is found that the diffusion coefficient of the d eterministic dynamics may be considerably reduced by the noise in agre ement with numerical simulations. It is shown that certain fundamental problems in the concept of deterministic diffusion without noise do n ot affect the validity of our result.