  Point defects in solids promise precise measurements of various quantities.
Especially magnetic field sensing using the spin of point defects has been of
great interest recently. When optical readout of spin states is used, point
defects achieve optical magnetic imaging with high spatial resolution at
ambient conditions. Here, we demonstrate that genuine optical vector
magnetometry can be realized using the silicon vacancy in SiC, which has an
uncommon S=3/2 spin. To this end, we develop and experimentally test sensing
protocols based on a reference field approach combined with multi frequency
spin excitation. Our works suggest that the silicon vacancy in an
industry-friendly platform, SiC, has potential for various magnetometry
applications at ambient conditions.
