An Efficient Source of Single Photons: A Single Quantum Dot in a   Micropost Microcavity
  We have demonstrated efficient production of triggered single photons by coupling a single semiconductor quantum dot to a three-dimensionally confined optical mode in a micropost microcavity. The efficiency of emitting single photons into a single-mode travelling wave is approximately 38%, which is nearly two orders of magnitude higher than for a quantum dot in bulk semiconductor material. At the same time, the probability of having more than one photon in a given pulse is reduced by a factor of seven as compared to light with Poissonian photon statistics. 
Matthew Pelton, Charles Santori, Jelena Vuckovic, Bingyang Zhang,   Glenn S. Solomon, Jocelyn Plant, and Yoshihisa Yamamoto