# Observation of dressed states of distant atoms with delocalized photons in coupled-cavities quantum electrodynamics

## TL;DR

This paper demonstrates the creation and observation of dressed states involving distant atoms and delocalized photons in a coupled-cavities quantum electrodynamics system, advancing quantum network research.

## Contribution

It introduces a novel all-fiber coupled-cavities QED setup that coherently connects distant atom-cavity systems and observes their dressed states with delocalized photons.

## Key findings

- Observation of dressed states of distant atoms
- Realization of fiber-dark normal mode with delocalized photons
- Potential platform for quantum networks and many-body physics

## Abstract

In a cavity quantum electrodynamics (QED) system, where atoms coherently interact with photons in a cavity, the eigenstates of the system are the superposition states of atoms and cavity photons, the so-called dressed states of atoms. When two cavities are connected by an optical fiber with negligible loss, the coherent coupling between the cavities gives rise to photonic normal modes. One of these normal modes is the fiber-dark mode, in which photons are delocalized in the two distant cavities. Here we demonstrate the setting of coupled-cavities QED, where two nanofiber cavity-QED systems are coherently connected by a meter-long low-loss channel in an all-fiber fashion. Specifically, we observe dressed states of distant atoms with delocalized photons of the fiber-dark normal mode. Our system will provide a platform for the study of delocalized atomic and photonic states, photonic many-body physics, and distributed quantum computation.