BROWNIAN SURFERS

We show that under certain conditions a travelling-wave field of force can trap an underdamped Brownian particle. This effect is most effici ent at zero temperature and for wave speeds smaller than a threshold v alue independent of the damping constant: the Brownian particle acts t hen as a Brownian surfer. Brownian surfers are sensitive to both the a mplitude of the dragging field and possible asymmetries of its wavefor m (travelling ratchets). (C) 1998 Published by Elsevier Science B.V.