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Proceedings Paper

Ratchets in homogeneous extended systems: internal modes and the role of noise
Author(s): Angel Sanchez; Luis Morales-Molina; Franz G. Mertens; Niurka R. Quintero; Javier Buceta; Katja Lindenberg
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Paper Abstract

We revisit the issue of directed motion induced by zero average forces in extended systems driven by ac forces. It has been shown recently that a directed energy current appears if the ac external force, f(t), breaks the symmetry f(t) = -f(t+T/2), T being the period, if topological solitons (kinks) existed in the system. In this work, a collective coordinate approach allows us to identify the mechanism through which the width oscillation drives the kink and its relation with the mathematical symmetry conditions. Furthermore, our theory predicts, and numerical simulations confirm, that the direction of motion depends on the initial phase of the driving, while the system behaves in a ratchet-like fashion if averaging over initial conditions. Finally, the presence of noise overimposed to the ac driving does not destroy the directed motion; on the contrary, it gives rise to an activation process that increases the velocity of the motion. We conjecture that this could be a signature of resonant phenomena at larger noises.

Paper Details

Date Published: 25 May 2004
PDF: 11 pages
Proc. SPIE 5471, Noise in Complex Systems and Stochastic Dynamics II, (25 May 2004); doi: 10.1117/12.546021
Show Author Affiliations
Angel Sanchez, Univ. Carlos III de Madrid (Spain)
Luis Morales-Molina, Univ. Bayreuth (Germany)
Franz G. Mertens, Univ. Bayreuth (Germany)
Niurka R. Quintero, Univ. de Sevilla (Spain)
Univ. de Granada (Spain)
Javier Buceta, Univ. of California/San Diego (United States)
Katja Lindenberg, Univ. of California/San Diego (United States)

Published in SPIE Proceedings Vol. 5471:
Noise in Complex Systems and Stochastic Dynamics II
Zoltan Gingl, Editor(s)

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