  Despite tremendous advances in the fundamentals and applications of cavity
quantum electrodynamics (CQED), investigations in this field have primarily
been limited to optical cavities composed of purely dielectric materials. Here,
we demonstrate a hybrid metal-dielectric nanocavity design and realize it in
the InAs/GaAs quantum photonics platform utilizing angled rotational metal
evaporation. Key features of our nanometallic light-matter interface include:
(i) order of magnitude reduction in mode volume compared to that of leading
photonic crystal CQED systems; (ii) surface-emitting nanoscale cylindrical
geometry and therefore good collection efficiency; and finally (iii) strong and
broadband spontaneous emission rate enhancement (Purcell factor ~ 8) of single
photons. This light-matter interface may play an important role in quantum
technologies.
