Light Manipulation via Tunable Collective Quantum States in Waveguide-Coupled Bragg and Anti-Bragg Superatoms

TL;DR

This study demonstrates how tunable collective quantum states in waveguide-coupled superconducting atom arrays can manipulate light, showing phenomena like transparency and bandgaps, with potential for quantum device applications.

Contribution

It introduces experimental control of Bragg and anti-Bragg superatoms in superconducting circuits, enabling tunable light manipulation in small quantum systems.

Findings

Observation of collectively induced transparency.

Realization of broad photonic bandgap.

Control of optical properties via atomic spacing and frequency.

Abstract

A many-body quantum system which consists of collective quantum states, such as superradiant and subradiant states, behaves as a multi-level superatom in light-matter interaction. In this work, we experimentally study one-dimensional superatoms in waveguide quantum electrodynamics with a periodic array of superconducting artificial atoms. We engineer the periodic atomic array with two distinct nearest-neighbor spacings, i.e., $d$=$\lambda_0/2$ and $d$=$\lambda_0/4$, which correspond to Bragg and anti-Bragg scattering conditions, respectively. The system consists of eight atoms arranged to maintain these specific interatomic distances. By controlling atomic frequencies, we modify Bragg and anti-Bragg superatoms, resulting in distinctly different quantum optical phenomena, such as collectively induced transparency and a broad photonic bandgap. Moreover, due to strong waveguide-atom couplings in superconducting quantum circuits, efficient light manipulations are realized in small-size systems. Our work demonstrates tunable optical properties of Bragg and anti-Bragg superatoms, as well as their potential applications in quantum devices.