Self-organized, noise-free escape of a coupled nonlinear oscillator chain

¹  Institute of Physics, Humboldt-University at Berlin - Newton Str. 15, D-12489 Berlin
²  Institut für Physik, Universität Augsburg - Universitätsstr. 1, D-86135 Augsburg, Germany

Received: 24 January 2007
Accepted: 1 March 2007

Abstract

We consider the self-organized escape of a chain of harmonically coupled units from a metastable state over a cubic potential barrier. The underlying dynamics is conservative and purely deterministic. The supply of a sufficient total energy transforms the chain into the nonlinear regime from which an initially, nearly uniform lattice configuration becomes unstable, yielding a redistribution with a strong localization of energy. A spontaneously emerging localized mode grows into the critical nucleus. Upon passing this transition state, the nonlinear chain performs a collective, deterministic escape event. Surprisingly, we find that such noise-free, collective nonlinear barrier crossing events yield a drastically diminished average escape time as compared to the one that is assisted by continuously impacting thermal noise. This beneficial enhancement of the rate of escape for the chain typically occurs whenever the ratio between the average energy supplied per unit in the chain and the potential barrier energy assumes small values.