Fig. 4: Spectral tuning of the nanocavity and enhanced atom-cavity interaction.

a The enhancement of the single center in the cavity requires spatial and spectral overlap. Spatial overlap was achieved in Fig. 3 and spectral overlap is achieved here by tuning the nanophotonic cavity. Cavity tuning as a function of the argon gas injection cycle. Gas injection modifies the effective index of cavity mode and tunes the resonance wavelength of the cavity that is shifted from ~1269 nm to ~1275 nm. As the cavity resonance is shifted towards the ZPL of the quantum center, the photoluminescence is enhanced to reach a maximum at ~1275 nm, where the spectral overlap is achieved. b Zero-phonon line intensity as a function of the detuning of the cavity. An enhancement larger than 30 is achieved on resonance. c Excited lifetime for cavity detuning of δ = 2.40 nm, δ = 0.23 nm, and δ = 0.00 nm. The lifetime of emitted photons shortens from 53.6 ns to 6.7 ns when the detuning between the cavity and emitter is decreased. The instrument response function of the pulsed laser has also been provided in the Supplementary Note 3. An 8-fold reduction in the lifetime is experimentally observed when the overlap is achieved compared to the off-resonance case. These results constitute the first all-silicon quantum light source using a silicon emissive center in a cavity, and the center can be further accelerated by designing cavities with higher quality factors as well as more deterministic positioning methods to further improve the emitter-cavity spatial overlap. The results will enable all-silicon quantum optics interfaces with silicon-emissive centers for scalable quantum optics.