  We report on the controlled coupling of a single nitrogen-vacancy (NV) center
to a surface plasmon mode propagating along a chemically grown silver nanowire.
We locate and optically characterize a single NV-center in a uniform dielectric
environment before we controllably position this emitter in the close proximity
of the nanowire. We are thus able to control the coupling of this particular
emitter to the nanowire and directly compare the photon emission properties
before and after the coupling. The excitation of single plasmonic modes is
witnessed and a total rate enhancement by a factor of up to 4.6 is
demonstrated.
