Precision magnetometry and imaging via quantum manipulation of spins in diamond

Abstract

.Precise control of quantum states is a cornerstone of quantum science and technology. Recently, a multi-level electronic spin system in a robust room-temperature solid, based on the nitrogen-vacancy (NV) color center in diamond, has emerged as a leading platform for quantum sensing as well as quantum information processing at room temperature. Developing new approaches to high-precision NV spin manipulation provides key insights for advancing these quantum technologies. In this thesis, I demonstrate three experimental methods for controlling NV spins with various concentrations toward high-performance magnetic field sensing and imaging. First, the wide-field optical magnetic microscopy experiment provides ensemble- NV control via continuous-wave electron spin resonance and camera-based parallel spin-state readout. This microscope offers a factor of 100 larger field-of-view compared to the confocal detection size, which enables magnetic imaging of populations of living bacteria. Second, the Fourier magnetic imaging experiment demonstrates for the first time multiple-NV control using phase encoding. Pulsed magnetic field gradients encode in the NV spin phase the information about the position of the NV centers as well as the external magnetic field in the Fourier-space. This scheme allows 100-fold improvement in spatial resolution beyond the optical diffraction limit, and has higher signal-to-noise ratio than other super-resolution imaging techniques when applied to NV spins. Third, the geometric phase magnetometry experiment employs single-NV control using a Berry sequence, consisting of off-resonant microwaves whose parameters vary along a cyclic path, thereby realizing 100 times larger magnetic field dynamic-range compared to the typical Ramsey-type interferometry approach. Finally, I discuss the possibilities of combining these techniques to realize various other quantum applications in future work.