Single Defect Centers in Diamond Nanocrystals as Quantum Probes for   Plasmonic Nanostructures
  We present two applications of a single nitrogen vacancy center in a nanodiamond as quantum probe for plasmonic nanostructures. Coupling to the nanostructures is achieved in a highly controlled manner by picking up a pre-characterized nanocrystal with an atomic force microscope and placing it at the desired position. Local launching of single excitations into a nanowire with a spatial control of few nanometers is demonstrated. Further, a two dimensional map of the electromagnetic environment of a plasmonic bowtie antenna was derived, resembling an ultimate limit of fluorescence lifetime nanoscopy. 
Andreas W. Schell, G\"unter Kewes, Tobias Hanke, Alfred Leitenstorfer,   Rudolf Bratschitsch, Oliver Benson and Thomas Aichele
physics.optics cond-mat.mes-hall