Hybridising NV centres with silicon nitride photonics for high efficiency sources of indistinguishable photons at 200 K

Abstract

Solid state atom-like systems have great promise for building quantum networks at scale 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. Recently, low-noise silicon nitride has been demonstrated as platform compatible with single spin and single photon manipulation [1]. We consider the nitrogen vacancy centre 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 > 50 %, improvable by external filtering. We analyse our design using FDTD simulations, and treat optical emission using a cavity QED master equation valid at and beyond strong coupling and which includes both ZPL broadening and sideband emission [2]. The design is compact (< 10 um), and owing to its planar geometry, can be fabricated using standard silicon processes. Our work therefore points towards scalable fabrication of non-cryogenic atom-like efficient sources of indistinguishable photons. [1] JA Smith, J Monroy-Ruz, JG Rarity, KC Balram. "Single photon emission and single spin coherence of a nitrogen vacancy centre encapsulated in silicon nitride" Appl. Phys. Lett. 116, 134001 (2020) [2] JA Smith, C Clear, KC Balram, DPS McCutcheon, JG Rarity. "NV centre coupled to an ultrasmall mode volume cavity: a high efficiency source of indistinguishable photons at 200 K" accepted for publication in Physical Review Applied (2021)