Atom-Photon Entanglement

TL;DR

This paper demonstrates entanglement between a single trapped atom and a photon at communication-friendly wavelengths, advancing the development of long-distance quantum networks.

Contribution

It introduces a novel single atom state analysis technique for full state tomography of atom-photon pairs, enabling future long-distance entanglement experiments.

Findings

High detection efficiency and entanglement fidelity achieved.

Successful full state tomography of atom-photon pairs.

Potential for loophole-free Bell tests at large distances.

Abstract

We report the observation of entanglement between a single trapped atom and a single photon at a wavelength suitable for low-loss communication over large distances, thereby achieving a crucial step towards long range quantum networks. To verify the entanglement we introduce a single atom state analysis. This technique is used for full state tomography of the atom-photon qubit-pair. The detection efficiency and the entanglement fidelity are high enough to allow in a next step the generation of entangled atoms at large distances, ready for a final loophole-free Bell experiment.