  A nanodiamond (ND) hosting nitrogen-vacancy (NV) color centers is attached on
the apex of an optical tip for near-field microscopy. Its fluorescence is used
to launch surface plasmon-polaritons (SPPs) in a thin polycrystalline gold
film. It is shown that the quantum nature of the initial source of light is
preserved after conversion to SPPs. This opens the way to a deterministic
quantum plasmonics, where single SPPs can be injected at well-defined positions
in a plasmonic device produced by top-down approaches.
