Atom-atom entanglement by single-photon detection

TL;DR

This paper demonstrates a practical scheme for entangling distant atoms using single-photon detection, achieving high rate and fidelity, and controlling the entangled state phase via interferometer path length adjustments.

Contribution

It experimentally implements a protocol for atom-atom entanglement via single-photon detection, confirming theoretical predictions and showcasing control over entangled states.

Findings

High-rate entanglement of distant ions achieved

Fidelity limited mainly by atomic motion

Phase control demonstrated through interferometer adjustments

Abstract

A scheme for entangling distant atoms is realized, as proposed in the seminal paper by Cabrillo et al. [Phys. Rev. A 59, 1025 (1999)]. The protocol is based on quantum interference and detection of a single photon scattered from two effectively one meter distant laser-cooled and trapped atomic ions. The detection of a single photon heralds entanglement of two internal states of the trapped ions with high rate and with a fidelity limited mostly by atomic motion. Control of the entangled state phase is demonstrated by changing the path length of the single-photon interferometer.