Hermitian Nonlinear Wave Mixing Controlled by a PT-Symmetric Phase Transition

TL;DR

This paper demonstrates how PT-symmetric phase transitions in non-Hermitian systems can be used to control Hermitian systems via coherent nonlinear wave mixing, enabling energy exchange and potential applications in photonics.

Contribution

It introduces a novel method of controlling Hermitian systems through PT-symmetric non-Hermitian phases using coherent nonlinear wave mixing, replacing traditional loss mechanisms.

Findings

PT-symmetric phase controls Hermitian system dynamics

Second harmonic generation induces non-Hermitian behavior

Energy exchange persists within the Hermitian system

Abstract

While non-Hermitian systems are normally constructed through incoherent coupling to a larger environment, recent works have shown that under certain conditions coherent couplings can be used to similar effect. We show that this new paradigm enables the behavior associated with the PT- symmetric phase of a non-Hermitian subsystem to control the containing Hermitian system through the coherent couplings. This is achieved in parametric nonlinear wave mixing where simultaneous second harmonic generation replaces the role of loss to induce non-Hermitian behavior that persists through a full exchange of power within the Hermitian system. These findings suggest a new approach for the engineering of dynamics where energy recovery and sustainability are of importance that could be of significance for photonics and laser science.