DESIGNING HIGH SENSITIVITY NUCLEAR INERTIAL SENSORS IN DIAMOND
The nitrogen-vacancy (NV) center in diamond is a mature platform for quantumtechnologies, consisting of an electron spin that has long coherence times and is sensitive to a variety of external fields at room temperature. These features make NV centers a useful resource for precision metrology and its electron spin has been used to design sensors for magnetic, electric, temperature, and strain fields. The nitrogen nuclear spin that is native to every NV center is also of interest since it presents an opportunity to build highly sensitive sensors. This potential high sensitivity of NV nuclear sensors comes from its small gyromagnetic ratio, which makes it insensitive to magnetic noise, and its long bare coherence time on the order of seconds. Developing these nuclear sensors is an active area of research, with multiple demonstrations successfully implementing the nuclear spin as a rotation sensor. However, the sensitivity of these sensors are orders of magnitude worse than conventional gyroscopes such as micorelectromechanical systems (MEMS) and ring laser gyroscopes. In this thesis, we will discuss the fundamental limitations behind the poor sensitivity of current nuclear spin sensors, which stems from the strong hyperfine interaction between the NV center’s electron spin and nuclear spin. This hyperfine interaction limits the coherence time of nuclear spins in diamond to the electron T1. We will also discuss strategies to decouple the nuclear and electron spins from each other, to extend the nuclear spin coherence time. In particular, we focus on strong driving of a magnetically forbidden double-quantum transition. We propose to drive this double-quantum transition using acoustic strain from a MEMS resonator fabricated on diamond and present the development and performance of a new generation of piezoelectric thin film bulk acoustic resonators on diamond that are designed for this application. Finally we also investigate and design a readout protocol for high sensitivity nuclear spin sensors operating beyond the electron T1 to guide future nuclear sensor development.