Eur. Phys. J. B 37, 79-83 (2004)
https://doi.org/10.1140/epjb/e2004-00031-3

Soliton ratchets out of point-like inhomogeneities

¹ Physikalisches Institut, Universität Bayreuth, 85440 Bayreuth, Germany
² Grupo Interdisciplinar de Sistemas Complejos (GISC) and Departamento de Matemáticas, Universidad Carlos III de Madrid, Avenida de la Universidad 30, 28911 Leganés, Madrid, Spain

Corresponding author: ^a anxo@math.uc3m.es

Received: 1 July 2003
Revised: 25 November 2003
Published online: 19 February 2004

Abstract

We introduce and study a novel design for a ratchet potential for soliton excitations. The potential is implemented by means of an array of point-like (delta) inhomogeneities in an otherwise homogeneous potential. We use collective coordinates which predict that the effective potential acting on the soliton is periodic but asymmetric and gives rise to the ratchet effect. Numerical simulations fully confirm this prediction; quantitative agreement is reached by an improved version of the theory. Although we specifically show that it is most interesting for building Josephson junction ratchets capable to rectify time-symmetric ac forces, the proposed mechanism is very general and can appear in many contexts, including biological systems.