Going beyond the double well: complex mode dynamics of effective coupled oscillators in infinite dimensional systems

TL;DR

This paper investigates complex dynamical behaviors of nonlinear wave modes in infinite-dimensional systems, extending the understanding of coupled oscillators beyond simple double well models to include chaos and energy transfer phenomena.

Contribution

It introduces a framework for analyzing large amplitude nonlinear modes in dispersive wave systems, revealing new dynamical regimes and extending oscillator models to 2D configurations.

Findings

Identification of long-lived large amplitude oscillations

Breakdown of Josephson-like oscillations and internal modes

Emergence of chaotic dynamics at high amplitudes

Abstract

In this work we explore how nonlinear modes described by a dispersive wave equation (in our example, the nonlinear Schrodinger equation) and localized in a few wells of a periodic potential can act analogously to a chain of coupled mechanical oscillators. We identify the small-amplitude oscillation modes of these `coupled wave oscillators' and find that they can be extended into the large amplitude regime, where some can `ring' for long times. We also identify prototypical case examples of more complex dynamical behaviour that can arise in such systems beyond the double well paradigm, including the breakdown of Josephson-like oscillations and of internal modes more generally, the transfer of energy out of/destabilization of fundamental oscillation modes and the emergence of chaotic oscillations for large amplitude excitations. We provide details of the phase perturbations required for experimental observations of such dynamics, and show that the oscillator formalism can be extended to predict large amplitude excitations in genuinely two-dimensional configurations.