  We propose and demonstrate a new approach for achieving strong light-matter
interactions with quantum emitters. Our approach makes use of a plasmon
resonator composed of defect-free, highly crystalline silver nanowires
surrounded by patterned dielectric distributed Bragg reflectors (DBRs). These
resonators have an effective mode volume (Veff) two orders of magnitude below
the diffraction limit and quality factor (Q) approaching 100, enabling
enhancement of spontaneous emission rates by a factor exceeding 75 at the
cavity resonance. We also show that these resonators can be used to convert a
broadband quantum emitter to a narrowband single-photon source with
color-selective emission enhancement.
