  We introduce a point-like scanning single-photon source that operates at room
temperature and offers an exceptional photostability (no blinking, no
bleaching). This is obtained by grafting in a controlled way a diamond
nanocrystal (size around 20 nm) with single nitrogen-vacancy color-center
occupancy at the apex of an optical probe. As an application, we image metallic
nanostructures in the near-field, thereby achieving a near-field scanning
single-photon microscopy working at room temperature on the long term. Our work
may be of importance to various emerging fields of nanoscience where an
accurate positioning of a quantum emitter is required such as for example
quantum plasmonics.
