Steady-state currents in sharp stochastic ratchets

We develop and analyze a model for particle transport in a Stochastic ratch et with a periodic piecewise linear potential, with diffusion coefficient D , where the force is discontinuous in position and fluctuating in time via additive telegraph noise with correlation time tau. We find asymptotic form ulas for the steady-state particle current J for large and small D and tau. For example, for small tau r, the sharp corners in the potential lead to J = O(tau(2) exp[-(D tau)(-1/2)]) + O(tau(5/2)), in contrast to O(tau(3)) wh en the potential is smooth. We show that diffusion can increase or decrease J, and derive an approximate equation for the value of D that maximizes J. [S1063-651X(99)05810-9].