Dynamic stabilization of the optical resonances of single nitrogen-vacancy centers in diamond

We report electrical tuning by the Stark effect of the excited-state structure of single nitrogen-vacancy (NV) centers located 100nm from the diamond surface. The zero-phonon line (ZPL) emission frequency is controllably varied over a range of 300GHz. Using high-resolution emission spectroscopy, we observe electrical tuning of the strengths of both cycling and spin-altering transitions. Under resonant excitation, we apply dynamic feedback to stabilize the ZPL frequency. The transition is locked over several minutes and drifts of the peak position on timescales 100ms are reduced to a fraction of the single-scan linewidth, with standard deviation as low as 16MHz (obtained for an NV in bulk, ultrapure diamond). These techniques should improve the entanglement success probability in quantum communications protocols.