  Optically addressable solid-state defects are emerging as one of the most
promising qubit platforms for quantum networks. Maximizing photon-defect
interaction by nanophotonic cavity coupling is key to network efficiency. We
demonstrate fabrication of gallium phosphide 1-D photonic crystal waveguide
cavities on a silicon oxide carrier and subsequent integration with implanted
silicon-vacancy (SiV) centers in diamond using a stamp-transfer technique. The
stamping process avoids diamond etching and allows fine-tuning of the cavities
prior to integration. After transfer to diamond, we measure cavity quality
factors ($Q$) of up to 8900 and perform resonant excitation of single SiV
centers coupled to these cavities. For a cavity with $Q$ of 4100, we observe a
three-fold lifetime reduction on-resonance, corresponding to a maximum
potential cooperativity of $C = 2$. These results indicate promise for high
photon-defect interaction in a platform which avoids fabrication of the quantum
defect host crystal.
