  Efficient coupling between solid state quantum emitters and plasmonic
waveguides is important for the realization of integrated circuits for quantum
information, communication and sensing. However, realization of plasmonic
circuits is still scarce, particularly due to challenges associated with
accurate positioning of quantum emitters near plasmonic resonators. Current
pathways for the construction of plasmonic circuits involve cumbersome and
costly methods such as scanning atomic force microscopy or mechanical
manipulation, where individual elements are physically relocated using the
scanning tip. Here, we introduce a simple, fast and cost effective chemical
self-assembly method for the attachment of two primary components of a
practical plasmonic circuit: a single photon emitter and a waveguide. Our
method enables coupling of nanodiamonds with a single quantum emitter (the
nitrogen-vacancy (NV) center) onto the terminal of a silver nanowire, by simply
varying the concentration of ascorbic acid (AA) in a reaction solution. The AA
concentration is used to control the extent of agglomeration, and can be
optimised so as to cause preferential, selective activation of the tips of the
nanowires. The nanowire-nanodiamond structures show efficient plasmonic
coupling of fluorescence emission from single NV centers into surface plasmon
polariton (SPP) modes, evidenced by a more than two-fold reduction in
fluorescence lifetime and an increase in fluorescence intensity.
