We study the transport of overdamped Brownian particles in a symmetrically periodic potential in the presence of an asymmetrically ac driving force and a time-delayed feedback. It is found that for low frequencies, the average velocity can be negative by changing the driving amplitude, for high frequencies, there exists an optimized driving amplitude at which the average velocity takes its maximum value. Additionally, there is a threshold value of driving amplitude below which no directed transport can be obtained for high frequencies. For the large value of the delay time, the average velocity is independent of the delay time.

Abstract:The transport of Brownian particles moving along a three-dimensional fluctuating tube is investigated in the presence of a load. The tube wall can fluctuate between two states. Coarsening the description of a process for the sake of simplifying the dynamic will result in an entropic barrier and an effective diffusion coefficient. It is found that we can control the asymmetric parameter and the load force to control the current direction and there is an optimized transition rate at which the current takes a maximum value.

The transport of overdamped Brownian particles in an asymmetric periodic potential was investigated in the presence of temporally asymmetric correlated two-state noise and a load. It was found that the interplay between temporal asymmetry and spatial asymmetry can bring about some peculiar phenomena. A reversal of the current will occur when the parameters are suitably chosen. A value of the potential height exists at which the current takes its maximal value. For very large values of the correlated time, the variation of the current is independent of the correlated time. Remarkably, we also observed that the correlated time cannot affect the value of the load at which the current reverses its direction.