In our experiments, NV centers have to be close to the diamond surface (within a few tens of nanometers) to couple to the evanescent field from GaP cavities. One way to deterministically create NV centers this close to the surface is via implantation of the diamond substrate with nitrogen ions. In addition to introducing nitrogen, the implantation process also creates vacancies. During a subsequent high-temperature anneal, vacancies diffuse to the implanted nitrogen atoms resulting in the formation of neutral NV0 centers. NV0 is then converted into the negatively charged NV- by a final low-temperature oxygen annealing step.

Photoluminescent resonant excitation studies:

One of the most important properties of the NV is the indistinguishability of its emitted photons.  Two NV's separated by large distances can be entangled if they emit identical photons. Unfortunately near-surface NV centers tend to suffer from inhomogeneous broadening and spectral diffusion. We are currently investigating methods of minimizing this spectral diffusion.

Ion implantation and annealing can also be used to form near surface SiV centers. In contrast to the NV center, the SiV's optical transitions are insensitive to electric field noise leading to stable optical emission. Unfortunately the spin coherence times of SiV- are significantly shorter than the NV- centers, limited by phonon induced dephasing, and must be cooled to milliKelvin for coherent spin control. We form SiV centers with the ultimate aim of studying SiV0 , which has been shown to have superior spin coherence times.