Entangling single atoms over 33 km telecom fibre

TL;DR

This paper demonstrates heralded entanglement between two remote single-atom quantum memories over 33 km of telecom fiber, advancing quantum network development by overcoming optical fiber losses with quantum frequency conversion.

Contribution

It reports the first long-distance entanglement of single-atom quantum memories over 33 km fiber using quantum frequency conversion, a key step for scalable quantum networks.

Findings

Heralded entanglement achieved over 33 km fiber link.

Quantum frequency conversion preserves polarization and reduces losses.

Milestone towards practical quantum network implementation.

Abstract

Heralded entanglement between distant quantum memories is the key resource for quantum networks. Based on quantum repeater protocols, these networks will facilitate efficient large-scale quantum communication and distributed quantum computing. However, despite vast efforts, long-distance fibre based network links have not been realized yet. Here we present results demonstrating heralded entanglement between two independent, remote single-atom quantum memories generated over fibre links with a total length up to 33 km. To overcome the attenuation losses in the long optical fibres of photons initially emitted by the Rubidium quantum memories, we employ polarization-preserving quantum frequency conversion to the low loss telecom band. The presented work represents a milestone towards the realization of efficient quantum network links.