Quantum optics in the solid state with diamond nanophotonics

Quantum networks require interfaces between photons and quantum bits. Nitrogen vacancy (NV) centers in diamond are a promising candidate for this interface: they are optically addressable, have spin degrees of freedom with long coherence times, and can be easily integrated into solid-state nanophotonic devices. The crucial optical feature of the NV is its zero-phonon line (ZPL), a cycling transition allowing coherent optical manipulation and read-out of the spin. However, the ZPL only accounts for 3-5\% of the NV emission, and previous methods of producing NV centers yield unstable ZPLs. I will present methods for controlling NV emission by coupling NV centers to nanophotonic devices. In particular, we create a high-density layer of NVs with stable ZPLs in high purity diamond; carve waveguides out of the diamond substrate; and fabricate high quality factor, small mode volume photonic crystal cavities around NVs in these waveguides. We observe an enhancement of the NV emission at the cavity resonance by a factor of 100. These devices will become building blocks for quantum information processing such as single photon transistors, enabling distribution of entanglement over quantum networks.