Indistinguishable photons from separated silicon-vacancy centers in   diamond
  We demonstrate that silicon-vacancy (SiV) centers in diamond can be used to efficiently generate coherent optical photons with excellent spectral properties. We show that these features are due to the inversion symmetry associated with SiV centers, and demonstrate generation of indistinguishable single photons from separate emitters in a Hong-Ou-Mandel (HOM) interference experiment.Prospects for realizing efficient quantum network nodes using SiV centers are discussed. 
Alp Sipahigil, Kay D. Jahnke, Lachlan J. Rogers, T. Teraji, J. Isoya,   Alexander S. Zibrov, Fedor Jelezko, Mikhail D. Lukin
quant-ph cond-mat.mtrl-sci physics.optics