  Rate of single-photon generation by quantum emitters (QEs) can be enhanced by
placing a QE inside a resonant structure. This structure can represent an
all-dielectric micro-resonator or waveguide and thus be characterized by
ultra-low loss and dimensions on the order of wavelength. Or it can be a metal
nanostructure supporting localized or propagating surface plasmon-polariton
modes that are of subwavelength dimensions, but suffer from strong absorption.
In this work, we develop a physically transparent analytical model of
single-photon emission in resonant structures and show unambiguously that,
notwithstanding the inherently high loss, the external emission rate can be
enhanced with plasmonic nanostructures by two orders of magnitude compared to
all-dielectric structures. Our analysis provides guidelines for developments of
new plasmonic configurations and materials to be exploited in quantum
plasmonics.
