Selective transport through periodic structures: directing Brownian motion and sorting chiral particles

by Ralf Eichhorn (Nordita)

Tuesday 26 Oct 2010, 13:30 → 14:30 Europe/Stockholm

122:026

We first address the Brownian motion of a particle which is exposed to a periodic potential and an external AC-driving.
Depending on the driving amplitude, the linear response to a weak DC-force along a symmetry axis of the periodic lattice consist in a mobility in practically any direction.
In particular, motion exactly opposite to the applied DC-force (absolute negative mobility) may arise. The basic physical mechanism consists in a spontaneous symmetry breaking of the unbiased deterministic particle dynamics.

In a second part we demonstrate how periodic potentials can be exploited for sorting small objects which only differ by their chirality. With the help of a static bias force, the two chiral partners can be made to move along orthogonal directions. Time-periodic external forces even lead to motion into exactly opposite directions.