Regensburg 2002 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 50: Statistische Physik fernab vom Gleichgewicht III

DY 50.2: Vortrag

Freitag, 15. März 2002, 10:30–10:45, H2

Quantum Brownian motion in ratchet potentials — •Stefan Scheidl¹ and Valerii Vinokur² — ¹Institut für Theoretische Physik, Universität zu Köln — ²Materials Science Division, Argonne National Laboratory

We examine the dynamics of quantum particles in a ratchet potential and subject to an ac force field. We develop a perturbative approach for weak ratchet potentials and force fields. Within this approach, we obtain an analytic description of dc current rectification and of current reversals. Various limiting cases – such as the classical limit, limit of high or low frequencies, or high temperatures – are evaluated explicitly. To gain insight in the intricate dependence of the rectified current on the various parameters, we identify characteristic scales and capture the response in terms of scaling functions. We pay particular attention to inertial effects and show that they are relevant, e.g., for the high temperatures, where we find a decay of the rectified current proportional to T^−17/6.