Towards inter-city entanglement generation using solid state spins in diamond.

Large scale networks where entanglement is generated and exploited between nodes are of great interest for both practical quantum communication applications as well as fundamental tests of nature[1]. The Nitrogen Vacancy (NV) centre in diamond provides an excellent platform for realizing such a network, with recent work demonstrating fast entanglement generation[2] and entanglement between the NV-centre qubit and a telecom photon [3].
We are working towards generating solid-state spin-spin entanglement between two Dutch cities via 30km of deployed fibre as first link in a European Quantum Internet. We will present our latest result towards generating indistinguishable photons from separate NV centers down-converted to telecom frequencies, an important prerequisite and stride forward towards creating high-fidelity entanglement over large distances.


[1] S. Wehner et al, Science 362 (2018)
[2] P. C. Humphreys et al, Nature 558, 268–273 (2018)
[3] A. Tchebotareva et al, PRL 123 (2019)