Revisiting the PT-symmetric Trimer: Bifurcations, Ghost States and Associated Dynamics

TL;DR

This paper thoroughly analyzes PT-symmetric trimers, exploring solution branches, bifurcations, ghost states, and dynamics, and connects theoretical findings with recent experimental results in optical waveguides.

Contribution

It generalizes the concept of ghost states from dimers to trimers, providing a comprehensive analysis of bifurcations, instabilities, and dynamics in PT-symmetric trimers.

Findings

Identification of all relevant solution branches

Connection of ghost states to symmetry-breaking bifurcations

Experimental validation in gain-loss-gain waveguide structures

Abstract

In this paper, we revisit one of the prototypical PT-symmetric oligomers, namely the trimer. We find all the relevant branches of "regular" solutions and analyze the bifurcations and instabilities thereof. Our work generalizes the formulation that was proposed recently in the case of dimers for the so-called "ghost states" of trimers, which we also identify and connect to symmetry-breaking bifurcations from the regular states. We also examine the dynamics of unstable trimers, as well as those of the ghost states in the parametric regime where the latter are found to exist. Finally, we present the current state of the art for optical experiments in PT-symmetric trimers, as well as experimental results in a gain-loss-gain three channel waveguide structure.