Resonant Excitation and Purcell Enhancement of Coherent Nitrogen-Vacancy Centers Coupled to a Fabry-Perot Micro-Cavity

Future quantum networks will enable technologies such as communications secured by the last of nature and distributed quantum communication. The nitrogen-vacancy (NV) center in diamond is a promising candidate for a quantum network node, with all basic node capabilities and few-node network operation demonstrated. Further scaling of NV-based quantum networks towards many nodes at large distances is hindered by the relatively small emission and collection probability of spin-selective photons from the NV center upon resonant excitation.  Integration into a cavity can boost both values via the Purcell effect, but poor optical coherence of near-surface NV centers has so far prevented their resonant optical control, as would be required for entanglement generation.

 

Here, we overcome this challenge, and demonstrate resonant addressing of individual, fiber-cavity-coupled NV centers, and collection of their Purcell-enhanced coherent photon emission [1]. Utilizing off-resonant and resonant addressing protocols, we extract Purcell factors of up to 4, consistent with a detailed theoretical model. Our results and model show the potential for increasing entanglement generation rates by up to two orders of magnitude using near-term improvements. Our work is an important step towards an NV-center based quantum network spanning metropolitan scales.

[1] M. Ruf, M.J. Weaver, S. van Dam, and R. Hanson, Phys. Rev. Appl. 15, 024049, 2021