Experimental realization of an optical antenna for collecting 99% of   photons from a quantum emitter
  We present the fabrication and characterization of an optical antenna that converts the dipolar radiation of a quantum emitter to a directional beam with 99% efficiency. Aside from its implications for efficient detection of nanoscopic emitters, this antenna facilitates a deterministic single-photon source with applications in quantum information processing, metrology and sub-shot-noise detection of absorption. We discuss the photophysical limitations of the currently used quantum emitters for the realization of such a device. 
X.-L. Chu, T.J.K. Brenner, X.-W. Chen, Y. Ghosh, J. A. Hollingsworth,   V. Sandoghdar, S. Goetzinger
quant-ph physics.optics