All-photonic entanglement swapping with remote quantum dots

TL;DR

This paper demonstrates deterministic all-photonic entanglement swapping between remote quantum dots with high fidelity, advancing quantum network scalability and reliability using solid-state emitters.

Contribution

It introduces the first all-photonic entanglement swapping with deterministic quantum dot sources, achieving high fidelity and nearly identical photon pairs from dissimilar quantum dots.

Findings

Achieved entanglement swapping fidelity of 0.71(2).

Used hybrid semiconductor-piezoelectric devices for photon generation.

Theoretical model explains and suggests improvements for protocol performance.

Abstract

Entanglement swapping is a protocol that details how to create entanglement between previously uncorrelated particles. Its all-photonic version - mediated by the interference of photon pairs generated by separate quantum systems-finds disparate applications in quantum networks. So far, all-photonic entanglement swapping between remote systems has been implemented only using sources that operate probabilistically. However, the scaling up of quantum networks requires deterministic quantum emitters that do not suffer from a trade-off between degree of entanglement and photonpair generation rate. Here, we demonstrate all-photonic entanglement swapping using photon-pairs generated by two separate GaAs quantum dots. The emitters are deterministically embedded in hybrid semiconductor-piezoelectric devices that make the entangled-photons from two dissimilar quantum dots nearly identical. Entanglement swapping is demonstrated with a fidelity as high as 0.71(2), more than 10 standard deviations above the classical limit. The experimental data are quantitatively explained by a theoretical model that also suggests how to boost the protocol performances. Our work opens the path to the exploitation of quantum dot entangled-photon sources in quantum repeater networks.