Photonic entanglement swapping with remote quantum dots

Entanglement swapping is a protocol that details how to create entanglement between previously uncorrelated particles. Its photonic version, mediated by the interference of photon pairs generated by separate quantum systems, finds disparate applications in quantum networks. So far, entanglement swapping with entangled photons from remote systems has been implemented only using probabilistic sources. However, the scaling up of quantum networks requires nonprobabilistic quantum emitters without a trade-off between the degree of entanglement and photon-pair generation rate. Here, we demonstrate 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 SDs above the classical limit. The experimental data are quantitatively explained by a theoretical model that also suggests how to boost the protocol performance. Our work opens the path to the exploitation of quantum dot entangled-photon sources in quantum repeater networks.