Nature Commun. 6, 7883 (2015)

Credit: NATURE PUBLISHING GROUP

The field of quantum plasmonics looks to exploit the strong confinement of the electromagnetic field for high-speed and ultra-compact on-chip devices for quantum technology. A major issue that hinders realistic implementations is minimizing the plasmon losses in order to increase their propagation length. To this end, Romain Quidant, Sergey Bozhevolnyi and colleagues study theoretically and experimentally the coupling between a quantum emitter and channel plasmon polaritons from a V-groove plasmonic waveguide. In particular, they deterministically place a single nitrogen–vacancy centre in diamond (a well-known bright photon source, operating at room temperature) inside the waveguide, based on the results of the theoretical investigation about its exact position for optimal coupling with the plasmons. They demonstrate that the emission from the nitrogen–vacancy centre is effectively guided for about 5 μm before being out-coupled into free-space propagating light. The high coupling efficiency between the emitter and the modes (42%) combined with the reported top-down fabrication technique bring plasmonic circuitry closer to reality.