Matthew Markham

We present a deployed quantum link between the Dutch cities Delft and The Hague separated by 10 kilometers, capable of generating solid-state heralded entanglement. This link is realized by employing NV center end nodes, connecting them with state-of-the-art Quantum Frequency Converters and a phase-stabilized architecture over 25 kilometers of telecom fiber. By capitalizing on the full heralding capabilities of the network link in combination with real-time feedback logic on the long-lived qubits, we demonstrate the delivery of a predefined entangled state on the nodes irrespective of the detector outcome. The extendable design, real-time control and compatibility with other qubit platforms and makes this architecture an excellent candidate for future metropolitan scale quantum networks.