Speaker
Jerzy Luczka
(University of Silesia)
Description
Anomalous diffusion can be detected in various systems. We show that
anomalous diffusion may emerge in a straightforward, one dimensional
classical nonequilibrium dynamics of a Brownian particle moving in a ratchet
potential and driven by both an unbiased time-periodic force and thermal
fluctuations of Gaussian nature. In a tailored parameter regime for which the
deterministic counterpart of the system is non-chaotic, the mean square
deviation of the Brownian particle coordinate evolves in three following stages:
initially as superdiffusion, next as subdiffusion and finally as normal diffusion in
the asymptotic long time limit. The lifetimes of superdiffusion and subdiffusion
can be controlled by system parameters and can last many many orders longer
than characteristic times of the system, thus being comfortably detectable
experimentally. The findings are distinct from existing knowledge and suggest
reconsideration of generally accepted opinion that anomalies are due to large
and rare fluctuations that are characterized by broad distributions with power-
law tails.
We explain the underlying mechanism standing behind the emergence of
diffusion anomalies and control of their regimes which are related to ergodicity
of the system and ultraslow relaxation of the particle velocity towards its non-
equilibrium stationary state.
Primary author
Jerzy Luczka
(University of Silesia)
Co-authors
Jakub Spiechowicz
(University of Silesia)
Peter Hanggi
(University of Augsburg)
