Surmounting collectively oscillating bottlenecks

TL;DR

This paper investigates how weak periodic driving combined with thermal noise can significantly enhance the escape rate of coupled nonlinear oscillators from a metastable state by triggering instabilities and localized modes, leading to faster activation.

Contribution

It reveals the mechanism by which external periodic forcing and thermal fluctuations synergistically accelerate escape dynamics in coupled oscillator systems, highlighting the role of parametric resonance and localized modes.

Findings

Optimal parameters drastically increase escape rates.

External periodic forcing triggers parametric resonance.

Escape time shows a minimum at specific coupling and frequency.

Abstract

We study the collective escape dynamics of a chain of coupled, weakly damped nonlinear oscillators from a metastable state over a barrier when driven by a thermal heat bath in combination with a weak, globally acting periodic perturbation. Optimal parameter choices are identified that lead to a drastic enhancement of escape rates as compared to a pure noise-assisted situation. We elucidate the speed-up of escape in the driven Langevin dynamics by showing that the time-periodic external field in combination with the thermal fluctuations triggers an instability mechanism of the stationary homogeneous lattice state of the system. Perturbations of the latter provided by incoherent thermal fluctuations grow because of a parametric resonance, leading to the formation of spatially localized modes (LMs). Remarkably, the LMs persist in spite of continuously impacting thermal noise. The average escape time assumes a distinct minimum by either tuning the coupling strength and/or the driving frequency. This weak ac-driven assisted escape in turn implies a giant speed of the activation rate of such thermally driven coupled nonlinear oscillator chains.