We report electrical tuning by the Stark effect of the excited-state structure of single nitrogen-vacancy (NV) centers located ≲100  nm from the diamond surface. The zero-phonon line (ZPL) emission frequency is controllably varied over a range of 300 GHz. 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 ≳100  ms are reduced to a fraction of the single-scan linewidth, with standard deviation as low as 16 MHz (obtained for an NV in bulk, ultrapure diamond). These techniques should improve the entanglement success probability in quantum communications protocols.

Room temperature single-photon emission and quantum characterization is reported for isolated defects in zinc oxide. The defects are observed in thin films of both in-house synthesized and commercial zinc oxide nanoparticles. Emission spectra in the red and infrared, second-order photon correlation functions, lifetime measurements, and photon count rates are presented. Both two- and three-state emitters are identified. Sub-band gap absorption and red emission suggest these defects are the zinc vacancy. These results identify a new source of single photons in a readily available wide band gap semiconductor material which has exceptional electrical, optical, and biocompatibility properties.

Diamond based technologies offer a material platform for the implementation of qubits for quantum computing. The photonic crystal architecture provides the route for a scalable and controllable implementation of high quality factor (Q) nanocavities, operating in the strong coupling regime for cavity quantum electrodynamics. Here we compute the photonic band structures and quality factors of microcavities in photonic crystal slabs in diamond, and compare the results with those of the more commonly-used silicon platform. We find that, in spite of the lower index contrast, diamond based photonic crystal microcavities can exhibit quality factors of Q=3.0x10(4), sufficient for proof of principle demonstrations in the quantum regime.

Fabrication of a hybrid diamond‐glass material is reported, by embedding diamond nanocrystals containing nitrogen‐vacancy (NV) color centers into tellurite soft glass. This material allows the fabrication of diamond photonic waveguides using well‐established soft glass techniques, such as microstructured optical fiber technology (the figure is a confocal image that shows color center fluorescence in a fiber).