Oscillating bound states in waveguide-QED system with two giant atoms

TL;DR

This paper investigates bound states in a waveguide-QED system with two giant atoms, revealing conditions for static and oscillating bound states and their potential for quantum information processing.

Contribution

It provides a detailed classification of bound states in a two-atom waveguide system, highlighting the emergence of oscillating bound states with multiple harmonic components.

Findings

Static bound states with persistent atomic excitations identified.

Oscillating bound states exhibit periodic exchange of excitations.

Additional quasi-dark modes enable high-capacity quantum information applications.

Abstract

We study the bound states in the continuum (BIC) in a system of two identical two-level giant atoms coupled to a one-dimensional waveguide. By deriving general dark-state conditions, we clarify how coupling configurations and atomic parameters influence decay suppression. Through analysis of the long-time dynamical behaviors of atoms and bound photons, we carry out a detailed classification of bound states and explore the connections between these dynamical behaviors and the system's intrinsic light-matter interactions. The system supports static bound states with persistent atomic excitations, and oscillating bound states with periodic atom-photon or atom-atom excitation exchange. Under certain conditions, oscillating bound states can contain more harmonic components owing to the emergence of additional quasi-dark modes, rendering them promising platforms for high-capacity quantum information processing. These findings advance the understanding of BIC in waveguide quantum electrodynamics with multiple giant atoms and reveal their prospective applications in quantum technologies.