Dresden 2006 – wissenschaftliches Programm
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DY: Dynamik und Statistische Physik
DY 46: Poster
DY 46.41: Poster
Donnerstag, 30. März 2006, 16:00–18:00, P1
Soliton ratchets in homogeneous nonlinear Klein-Gordon systems — •Luis Morales-Molina1, Niurka Quintero2, Angel Sanchez3, and Franz Mertens4 — 1Max-Planck Institut f ür Physik Komplexer Systeme, 01187 Dresden, Germany — 2Departamento de Fisica Aplicada I, E.U.P.,*Universidad de Sevilla, 41011 Sevilla, Spain — 3Departamento de Matematicas, Universidad Carlos III de Madrid, 28911 Leganes, Madrid, Spain — 4Physikalisches Institut, Universität Bayreuth, D-85440 Bayreuth, Germany
We study in detail the ratchet-like dynamics of topological solitons in homogeneous nonlinear Klein-Gordon systems driven by a bi-harmonic force. By using a collective coordinate approach with two degrees of freedom, namely the center of the soliton, $X(t)$, and its width, $l(t)$, we show, first, that energy is inhomogeneously pumped into the system, generating as result a directed motion; and, second, that the breaking of the time shift symmetry gives rise to a resonance mechanism that takes place whenever the width $l(t)$ oscillates with at least one frequency of the external ac force. In addition, we show that for the appearance of soliton ratchets, it is also neccesary to break the time-reversal symmetry. We analyze in detail the effects of dissipation in the system, calculating the average velocity of the soliton as a function of the ac force and the damping. We find current reversal phenomena depending on the parameter choice and discuss the important role played by the phases of the ac force. Our analytical calculations are confirmed by numerical simulations of the full partial differential equations of the sine-Gordon and $∖phi^4$ systems, which are seen to exhibit the same qualitative behavior.