Noise-induced currents and reliability of transport in frictional ratchets

We study the coherence of transport of an overdamped Brownian particle in frictional ratchet system in the presence of external Gaussian white noise fluctuations. The analytical expressions for the particle velocity and diffusion coefficient are derived for this system and the reliability or coherence of transport is analysed by means of their ratio in terms of a dimensionless Péclet number. We show that the coherence in the transport can be enhanced or degraded depending sensitively on the frictional profile with respect to the underlying potential.