Nitrogen-Vacancy Center Coupled to an Ultrasmall-Mode-Volume Cavity: A High-Efficiency Source of Indistinguishable Photons at 200 K

Solid-state atomlike systems have great promise for linear optic quantum computing and quantum communication but are burdened by phonon sidebands and broadening due to surface charges. Nevertheless, coupling to a small-mode-volume cavity would allow high rates of extraction from even highly dephased emitters. We consider the nitrogen-vacancy center in diamond, a system understood to have a poor quantum optics interface with highly distinguishable photons, and design a silicon nitride cavity that allows 99% efficient extraction of photons at 200 K with an indistinguishability of $g$ 50%, improvable by external filtering. We analyze our design using Lumerical fdtd simulations and treat optical emission using a cavity-QED master equation valid at and beyond strong coupling and that includes both zero-phonon line broadening and sideband emission. The simulated design is compact ($l10\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}\mathrm{m}$) and, owing to its planar geometry, can be fabricated using standard silicon processes. Our work therefore points toward scalable fabrication of noncryogenic atomlike efficient sources of indistinguishable photons.