Hybrid Quasi-Bound State in the Continuum at Topological Quantum Optics Interface

TL;DR

This paper introduces a topological quasi-bound state in the continuum (quasi-BIC) in a quantum optics interface, enabling photon localization, long-lived entanglement, and potential for ultranarrow amplification in photonic devices.

Contribution

It reports the discovery of a hybrid topological quasi-BIC formed via quantum interference, revealing new light-matter interaction phenomena at the topological quantum optics interface.

Findings

Existence of a topological quasi-BIC in atom-waveguide systems

Long-lived photon-atom entanglement observed

Potential for directional ultranarrow amplification

Abstract

Topological manipulation of light provides a versatile toolbox for photonic technologies. Here, we show that a topological atom array can induce photon localization in a waveguide via symmetry-protected light-matter interaction. Long-lived photon-atom entanglement reveals the existence of a novel topological quasi-bound state in the continuum (quasi-BIC). This hybrid light-matter quasi-BIC is formed at a critical coupling condition via collectively induced absorption, which is produced by quantum interference between edge and bulk states. We uncover the time-reversed relation between topological quasi-BIC and light amplification. Interestingly, one can realize a directional ultranarrow amplifier by means of critical coupling. Our work demonstrates an unconventional quasi-BIC at a topological quantum optics interface with potential applications in quantum devices.