Competition and cooperation between thermal noise and external driving force

We consider the transport of an overdamped Brownian particle moving in a rocked flashing ratchet-like potential. Together with a zero-mean driving force and a thermal white noise, the direction and behavior of the movement of the particle can be controlled. The expression of current is obtained by means of the perturbation approximation for fast flashing cases. Both the average velocity and position of the particle are simulated by use of the Langevin approach. The current reversal and the stepping motion of the particle are obtained and shown.