Quantum network nodes with silicon-vacancy center and coupled nuclear spins in diamond nanocavities

We realize quantum-network nodes based on silicon-vacancy color centers in diamond nanocavities coupled to nearby nuclear spins. A high cooperativity SiV-cavity interface and efficient tapered-fiber collection allows for single-shot readout of the SiV electronic spin. With dynamical decoupling sequences, we measure a coherence time of 400μs. We observe coupling to nearby ¹³C spins and demonstrate coherent control of the SiV-¹³C register. By using these nuclear spins, we realize a quantum memory exceeding 1ms. Together with our previous work, these results pave the way for quantum computation based on 2D cluster states with more than 10 photons, and quantum communication based on quantum repeaters.