Entropic transport in energetic potentials

We study the transport of point size particles in micro-sized two-dimensional periodic channels, exhibiting periodically varying cross-sections. The particles are subjected to a constant external force acting alongside the direction of the longitudinal channel axis and a varying force stemming from a periodic potential profile. While particle transport in tilted periodic potentials is facilitated by noise, the transport through pores with periodically varying cross-sections worsens with increasing noise level, i.e. increasing temperature. The competition between the noise-assisted propagation for energetic potentials and the hampered transport in confined structures leads to a striking, non-monotonic behavior which sensitively depends on the phase lag of the periodic channel structure and the periodic potential. By controlling this phase lag the symmetry could be broken and rectification observed. (C) 2010 Elsevier B.V. All rights reserved.