In modern-day research, magnetometry provides valuable information for a wide range of studies. Among all the different forms of magnetometers, the nitrogenvacancy (NV) lattice defect in diamond has emerged as a powerful magnetic field sensor thanks to the combination of sensitivity, spatial resolution and versatile capabilities. High-fidelity microwave control and optical readout of the NV spin over a wide range of conditions has enabled applications in condensed matter physics, chemistry, biology, geoscience and many more. In particular, its capability of visualizing magnetic phenomena with high spatial resolution has proven to be a powerful tool in both fundamental physics and applied sciences. Advances in NV magnetometry in the past decade have led to numerous breakthroughs, especially in revealing the nanoscale physics of condensed matter systems. However, the free-space optics generally used for optical interrogation of the NV spins are challenging to realize in cryogenic, intra-cellular, or other hard-to-reach environments. As such, realizing robust all-fiber-based NV probes with efficient optical readout could enable new measurements in low-temperature (quantum) or biological systems...@en

Superconductors expel magnetic fields, a phenomenon known as the Meissner effect. This effect makes it notoriously difficult to predict the magnetic field around a superconductor. One successful way of calculating these fields is through conformal mappings; coordinate transformations that preserve Maxwell's equations of magnetic fields in free space. These were first described by Norris and later improved by Brandt. In this bachelor thesis, conformal mappings are introduced and applied to 8 situations of magnetic field screening of an increasingly complex nature. We look at the screening of applied magnetic fields and of magnetic fields due to a bias current running through a wire itself. We later compare these results with experimental observations of the Van der Sar lab in Delft and measurements from other papers.

Spin-waves, the propagation of circular preccession of spins, have been offered as a way to replace electric currents as information carriers. The overwhelming advantage being the lack of moving charges and Ohmic losses. In this context, the search for an efficient method of detection of becomes crucial. Nitrogen vacancy centers in diamond offer a highly sensitive and effective solution. These diamond lattice defects have quan- tum and optical features allowing them to be used to quantify the surrounding magnetic field. This project is composed of a theoretical study of spin waves followed by an experimental section where AC magnetometry is tried out as a detection method. First the computations for the dispersion relation of spin waves in a ferro- magnetic material where done. A simplified version assuming homogeneity in one direction is presented and then an expansion considering a wave mode of the first order in the previously constant direction is attempted. An analysis on the efficiency of spin wave generation outlines the conditions on the wavelength and the po- larisation needed to correctly drive spin waves while being able to measure them using NV centers. Then the experimental setup and steps of AC magnetometry are layed out. The results of a measurement are shown and are in alignment with the theoretical predictions, proving this to be a valid method.