CONSTRUCTIVE ROLE OF NOISE - FAST FLUCTUATION ASYMPTOTICS OF TRANSPORT IN STOCHASTIC RATCHETS

lThe constructive role of random fluctuations is studied in the contex t of transport in stochastic ratchets. We discuss the interplay of ind ependent white (thermal) and discrete (external) noises and their gene ration of transport in anisotropic potentials. The constructive cooper ation of such fluctuations is most apparent in the asymptotic limit of fast discrete-valued noise, a limit which presents some interesting m athematical features. We describe the asymptotic analysis of the curre nt in the limit of fast external noise, pointing out the strong qualit ative dependence of the current on the interplay of the independent no ise sources and its surprising sensitivity to the regularity of the un derlying anisotropic ratchet potential. (C) 1998 American Institute of Physics.