Phenomenon of Repeated Current Reversals in the Brownian Ratchet

We study the probability current of the Brownian particles in a tilted periodic piecewise linear ``saw-tooth'' potential. It is found that the stationary probability current takes on a maximum value at a given additive noise if the intensity of the multiplicative noise is appropriate and at the same time both noises are correlated; and the direction of the stationary probability current is reversed more than once upon some certain correlation intensities between both noises. It is proven that the occurrence of current reversal is only dependent on the relative intensity of the multiplicative and additive noises, but has nothing to do with the absolute intensities of the two noises.