Coherent spin control of a nanocavity-enhanced qubit in diamond
  A central aim of quantum information processing is the efficient entanglement of multiple stationary quantum memories via photons. Among solid-state systems, the nitrogen-vacancy (NV) centre in diamond has emerged as an excellent optically addressable memory with second-scale electron spin coherence times. Recently, quantum entanglement and teleportation have been shown between two NV-memories, but scaling to larger networks requires more efficient spin-photon interfaces such as optical resonators. Here, we demonstrate such NV-nanocavity systems with optical quality factors approaching 10,000 and electron spin coherence times exceeding 200 $\mu$s using a silicon hard-mask fabrication process. This spin-photon interface is integrated with on-chip microwave striplines for coherent spin control, providing an efficient quantum memory for quantum networks. 
Luozhou Li, Tim Schr\"oder, Edward H. Chen, Michael Walsh, Igal Bayn,   Jordan Goldstein, Ophir Gaathon, Matthew E. Trusheim...
quant-ph physics.atom-ph physics.optics