| This thesis presents works not only to understand the spin degree of freedom present in the nitrogen-vacancy defect in diamond: its internal structure and its relation to its environment, but also to find novel applications of it in metrology. First, a mathematical model is develop to understand how this defect couples to a nuclear spin bath of Carbon 13 which constitutes the main dephasing mechanism in pure natural diamond. Next, we demonstrate the use of this defect to sense external oscillating magnetic fields. The high sensitivity and the small sensing volume achieved when a defect is placed in a nanocrystal of few tents of nanometers in diameter, allows this sensor to detect single electronic spins and even single nuclear spins. This sensitivity, proportional to the signal to noise per readout, can be improve by the help of the environment of this defect. We show that strongly interacting nearby nuclei can enable repetitive readout schemes to improve the signal to noise of the electronic spin signal. We also combine ideas from the microscopy community such as stimulated emission depletion to enable high spatial resolution magnetometry. Finally, we develop a formalism based on group theory to understand the internal structure of defects in solids such as their selection rules and the effect of spin-spin and spin-orbit interactions even when perturbations reduce the symmetry group of the system. |
