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Brownian motors: current fluctuations and rectification efficiency

L. Machura·M. Kostur·P. Talkner·J. Luczka·F. Marchesoni·P. Hanggi
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Abstract

With this work we investigate an often neglected aspect of Brownian motor transport: The rôle of fluctuations of the noise-induced current and its consequences for the efficiency of rectifying noise. In doing so, we consider a Brownian inertial motor that is driven by an unbiased monochromatic, time-periodic force and thermal noise. Typically, we find that the asymptotic, time- and noise-averaged transport velocities are small, possessing rather broad velocity fluctuations. This implies a corresponding poor performance for the rectification power. However, for tailored profiles of the ratchet potential and appropriate drive parameters, we can identify a drastic enhancement of the rectification efficiency. This regime is marked by persistent, uni-directional motion of the Brownian motor with few back-turns, only. The corresponding asymmetric velocity distribution is then rather narrow, with a support that predominantly favors only one sign for the velocity.

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L. Machura, M. Kostur, P. Talkner, J. Luczka, F. Marchesoni, P. Hanggi. 2004-09-13. Brownian motors: current fluctuations and rectification efficiency. https://doi.org/10.1103/physreve.70.061105

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