Single crystal diamond membranes for quantum networking and sensing*

Atomic defects in single crystal diamond, such as nitrogen-vacancy centers and silicon-vacancy centers, are promising qubit candidates for quantum communication and sensing. However, there are difficulties to fully utilize their advantages in bulk diamond due to its high refractive index and limited nanofabrication methods. In order to allow better integration flexibility of color centers while maintaining their coherence properties, we developed a process to create high quality, atomically smooth, large-scale single-crystal diamond membranes with no preference on carrying wafer choices. Herein we will present the fabrication steps in detail, including He⁺ implantation, CVD overgrowth, membrane undercut and transfer, backside etching, and additional patterning. Some recent progress related to the membrane integration will also be demonstrated, namely, nanophotonic cavity integration and strain engineering, which would be beneficial in multi-qubit networks, hybridized quantum systems, and quantum sensing applications.