Hybrid Integration of GaP Photonic Crystal Cavities with Silicon-Vacancy Centers in Diamond by Stamp Transfer*

Optically addressable solid-state defects, such as the negatively charged silicon-vacancy (SiV) center in diamond, have shown promise as a platform for quantum networks. For such applications, the integration of the defect with a nanophotonic cavity at high cooperativity (C >> 1) is necessary to operate with high fidelity and efficiency (e.g. via the Purcell effect). However, performing such integration while also maintaining the spectral and charge-state stability of the defect remains a challenge. In this work we demonstrate the fabrication of a gallium phosphide 1-D photonic crystal waveguide cavities which is then integrated with implanted SiV centers in diamond in a hybrid geometry via a stamp-transfer technique. This technique avoids exposure of the diamond to plasma and allows for fine tuning of the cavity resonance prior to transfer, thereby reducing potential damage to the defect environment. The transferred devices have measured quality factors (Q) as high as 8900. We perform time-resolved and resonant excitation photoluminescence spectroscopy of single SiV coupled to a device of Q = 4100 and observe a 3-fold reduction of the SiV excited state lifetime corresponding to an estimated Purcell enhancement exceeding 30 and maximum cooperativity C = 2. These results indicate that hybrid integration is a promising pathway towards quantum networking with solid-state defects.