On-chip single photon emission from an integrated semiconductor quantum   dot into a photonic crystal waveguide
  We demonstrate the in-plane emission of highly-polarized single photons from an InAs quantum dot embedded into a photonic crystal waveguide. The spontaneous emission rates are Purcell-enhanced by the coupling of the quantum dot to a slow-light mode of the waveguide. Photon-correlation measurements confirm the sub-Poissonian statistics of the in-plane emission. Under optical pulse excitation, single photon emission rates of up to 19 MHz into the guided mode are demonstrated, which corresponds to a device efficiency of 24%. These results herald the monolithic integration of sources in photonic quantum circuits. 
Andre Schwagmann, Sokratis Kalliakos, Ian Farrer, Jonathan P.   Griffiths, Geb A. C. Jones, David A. Ritchie, and Andrew J. ...
cond-mat.mes-hall physics.optics