A platform for cavity QED studies of silicon-vacancy center in the good cavity limit

Cavity QED systems of color centers such as silicon-vacancy (SiV) centers in diamond provide an experimental platform for the implementation of quantum networks. Considerable successes, including the demonstration of key ingredients of quantum networks, have been achieved with the use of photonic crystal optical resonators, which operate in the bad-cavity limit due to the large decay rate of the optical modes. Here, we report the development of an alternative experimental platform, which takes advantage of high Q-factor whispering gallery optical modes (WGMs) in a silica resonator. In this system, SiV centers in a 100 nm thick diamond membrane couple to evanescent fields of WGMs in a silica microsphere. Stretch tuning of the WGMs is used to control the detuning between a SiV center and a WGM. We show that this cavity QED system can operate in the good-cavity limit, for which the cavity linewidth is small compared with both the SiV linewidth and the single-photon dipole coupling rate. Additional experimental results on the coupling between a single SiV center and a WGM will also be presented.