Brownian pump induced by the phase difference between the potential and the entropic barrier

Abstract

Transport of Brownian particles in a finite channel is investigated in the presence of a symmetric potential and an unbiased external force. It is found that the phase difference between the potential (energetic barriers) and the entropic barrier can break the symmetry of the system and control the transport of Brownian particles. Especially, the particles can be pumped through the channel from a reservoir at low concentration to one at the same or higher concentration. There exist optimized values of the parameters (the temperature and the amplitude of the external force) at which the pumping capacity takes its maximum value. The pumping capacity decreases with increasing the radius at the bottleneck of the channel.