Berlin 2008 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 4: Brownian motion and transport

DY 4.10: Vortrag

Montag, 25. Februar 2008, 16:30–16:45, MA 004

Ratchet effect caused by internal degree of freedom — •Sebastian von Gehlen, Mykhaylo Evstigneev, and Peter Reimann — Universität Bielefeld, Universitätsstraße 25, 33615 Bielefeld

A dimer consisting of two dissimilar components is considered. It is assumed that the two dimer components are in contact with the same heat bath and find themselves in periodic potentials of the same wavelength but different amplitudes modulated synchronously in time. It is shown that this model exhibits the ratchet effect, i.e., directed transport in the absence of any external bias. An accurate analytic approximation for the dimer's velocity and diffusion coefficient is obtained. The system exhibits phenomena similar to stochastic resonance and resonant activation: its velocity is maximized by adding an optimal amount of noise and by tuning the driving frequency to an optimal value. Furthermore, there exists an optimal coupling strength at which the velocity is the largest.