Phase and Amplitude Dynamics in Large Systems of Coupled Oscillators: Growth Heterogeneity, Nonlinear Frequency Shifts and Cluster States

TL;DR

This paper explores how heterogeneity and nonlinear frequency shifts influence the collective dynamics of large coupled oscillator systems, revealing conditions for various synchronized and complex states.

Contribution

It provides a detailed analysis of the effects of amplitude growth heterogeneity and nonlinear frequency shifts on large oscillator networks, identifying conditions for different attractor states.

Findings

Existence of a single-cluster locked state at low nonlinear frequency shift

Emergence of multi-cluster, periodic, chaotic, and quasiperiodic states at higher shifts

Dependence of macroscopic dynamics on coupling strength and frequency shift parameters

Abstract

This paper addresses the behavior of large systems of heterogeneous, globally coupled oscillators each of which is described by the generic Landau-Stuart equation, which incorporates both phase and amplitude dynamics of individual oscillators. One goal of our paper is to investigate the effect of a spread in the amplitude growth parameter of the oscillators and of the effect of a homogeneous nonlinear frequency shift. Both of these effects are of potential relevance to recently reported experiments. Our second goal is to gain further understanding of the macroscopic system dynamics at large coupling strength, and its dependence on the nonlinear frequency shift parameter. It is proven that at large coupling strength, if the nonlinear frequency shift parameter is below a certain value, then there is a unique attractor for which the oscillators all clump at a single amplitude and uniformly rotating phase (we call this a single-cluster "locked state"). Using a combination of analytical and numerical methods, we show that at higher values of the nonlinear frequency shift parameter, the single-cluster locked state attractor continues to exist, but other types of coexisting attractors emerge. These include two-cluster locked states, periodic orbits, chaotic orbits, and quasiperiodic orbits.