Photon-Photon Entanglement with a Single Trapped Atom

TL;DR

This paper demonstrates a deterministic method to generate photon-photon entanglement mediated by a single trapped rubidium atom in a cavity, achieving high fidelity and Bell inequality violation, advancing quantum network technology.

Contribution

The work introduces a cavity-QED based protocol for deterministic photon-photon entanglement using a single trapped atom, with high fidelity and Bell violation.

Findings

Bell inequality violation of S=2.5

Fidelity exceeding 90%

Deterministic entanglement generation

Abstract

An experiment is performed where a single rubidium atom trapped within a high-finesse optical cavity emits two independently triggered entangled photons. The entanglement is mediated by the atom and is characterized both by a Bell inequality violation of S=2.5, as well as full quantum-state tomography, resulting in a fidelity exceeding F=90%. The combination of cavity-QED and trapped atom techniques makes our protocol inherently deterministic - an essential step for the generation of scalable entanglement between the nodes of a distributed quantum network.