Quantum acoustic control of diamond nitrogen-vacancy centers

Abstract

Diamond nitrogen-vacancy (NV) centers are a promising platform for solid state quantum technologies, owning to their intrinsic long-lived spin coherence, coherent optical orbital transition and efficient coupling to ambient fields. With recent development in quantum state control and read-out techniques, and progress in device engineering, NV centers have seen many applications in quantum information science and precision metrology. Among them, diamond MEMS (microelectromechanical systems) devices represent a new modality of hybrid quantum mechanical systems, allowing acoustic control of NV center states through electron-phonon coupling. Diamond gigahertz (GHz) mechanical resonators containing NV centers are particularly interesting, as they enable access to magnetically forbidden transitions, such as double quantum spin transition and orbital state control in the sideband-resolved limit. Moreover, they offer the capability of quantum ground state cooling at cryogenic temperature and are compatible with other quantum systems operating at microwave frequency. This thesis reports on diamond mechanical resonator device engineering and its application to acoustic control of NV center quantum states. We fabricate high quality diamond bulk acoustic resonators with GHz modes and integrated NV centers. Driving the resonator creates direct coupling of phonons to NV center electron spin and orbital states. At room temperature, we observe both single and double quantum spin transitions driven by phonons. Through improved device engineering, we demonstrate efficient acoustic control of NV center spin states using a semi-confocal high over-tone resonator. At cryogenic temperature, we probe the orbital states of a single NV center using photoluminescence excitation (PLE) spectroscopy and demonstrate optical transition engineering using GHz phonons. This work studies NV center electron-phonon interactions in detail from a physical aspect, and also promotes diamond acoustic devices in quantum technological applications.