Implications of exceptional points for few-photon transport in waveguide quantum electrodynamics

TL;DR

This paper reveals a fundamental link between exceptional points in non-Hermitian systems and the properties of few-photon bound states in waveguide QED, showing that the tightest photon binding occurs at these points.

Contribution

It demonstrates that exceptional points in waveguide QED systems determine the strongest photon-photon interactions, providing a new quantum signature and control mechanism.

Findings

The tightest photon bound state occurs at the exceptional point.

Explicit computation with a Jaynes-Cummings system confirms the connection.

Exceptional point physics can be used to control photon interactions.

Abstract

We identify a general connection between the physics of exceptional points in non-Hermitian systems and the few-photon bound states in waveguide quantum electrodynamics (QED) systems. We show that, in waveguide QED systems where the local quantum system exhibits an exceptional point, the tightest-bound few-photon bound state occurs at the exceptional point. We illustrate this connection with an explicit computation on a waveguide QED system in which a waveguide is coupled to a Jaynes-Cummings system. Our result provides a quantum signature of the exceptional point physics and indicates that the physics of exceptional point can be used to understand and control the photon-photon interaction.