Visible-wavelength optomechanical cavity for realizing spin-phonon coupling of the silicon vacancy center in diamond

The silicon vacancy center in diamond (SiV) is a promising candidate for use as a node in a quantum network, in part due to its ability to emit indistinguishable single photons from nano-cavities, its high cooperativity as a spin-photon interface, and its high spin-strain susceptibility. The latter opens the door for the SiV spin state to be manipulated via a spin-phonon interface, which has been investigated using classical surface acoustic waves in bulk diamond. Alternatively, a spin-phonon interface can be probed using an optomechanical cavity, in particular one that is resonant with the optical transition of the SiV to allow efficient spin readout. With this in mind, we have designed and fabricated a visible-wavelength optomechanical cavity in diamond. In particular, we have utilized a novel cavity design that results in a small mechanical mode volume, which is beneficial towards producing high spin-phonon coupling rates. Our work is a step towards strong spin-phonon coupling of the SiV center for hybrid quantum networks.