Quantum Register Based on Si^29-Vacancy Defect in Diamond*

Implementation of long range quantum networks requires quantum nodes with multiple interacting qubits which can be used to collect, store, and process information communicated via photonic channels. Silicon vacancy (SiV) centers in diamond photonic nanocavities are among the most promising candidate for such nodes due to their highly effective spin-photon interface. We present a novel system based on silicon-29 vacancy centers, combing a reproducible, predictable nuclear spin qubit as well as the SiV electronic spin with a single node. We demonstrate full coherent control of this 2-qubit register through quantum gates mediated by microwave and RF signals sent using on-chip coplanar waveguides. Using the strong coupling between the nuclear and electronic spins, we demonstrate fast, high-fidelity gates as well as individual initialization and readout of the qubits. These demonstrations pave the way for nuclear memory-enhanced quantum repeater protocols, as well as entanglement distillation protocols.