Experimental open air quantum key distribution with a single photon   source
  We present a full implementation of a quantum key distribution (QKD) system with a single photon source, operating at night in open air. The single photon source at the heart of the functional and reliable setup relies on the pulsed excitation of a single nitrogen-vacancy color center in diamond nanocrystal. We tested the effect of attenuation on the polarized encoded photons for inferring longer distance performance of our system. For strong attenuation, the use of pure single photon states gives measurable advantage over systems relying on weak attenuated laser pulses. The results are in good agreement with theoretical models developed to assess QKD security. 
Romain Alleaume, Francois Treussart, Gaetan Messin, Yannick Dumeige,   Jean-Francois Roch, Alexios Beveratos, Rosa Brouri-Tu...