High-precision low-energy experiments are one of the best ways we have of probing physics beyond the standard model (BSM). One BSM prediction is a small but non-zero electric dipole moment for the neutron (nEDM). This quantity means that the neutron breaks a fundamental symmetry of nature, the symmetry between particles and their anti-particles. This symmetry is known as Charge-Parity (CP) symmetry, and finding a new system that violates it could help explain (among other things) the matter-antimatter asymmetry in the early universe.

The electric dipole moment (EDM) of any particle is very sensitive to electric and magnetic fields. In order to measure the neutron EDM (nEDM) to our desired precision, the magnetic field present in the experiment must be known with a statistical precision of 10 fT over the nEDM measurement period (one Ramsey cycle). In addition, any gradients up to a third order polynomial field expansion must also be identified, as they contribute to systematic uncertainty.

I develop the theoretical framework describing magnetic fields in the TRIUMF Ultra Cold Advanced Neutron (TUCAN) nEDM experiment, prescribe a method by which scalar field measurements can be used to extract systematic magnetic field dependant effects, and build a proof of concept optical magnetometer meeting the above requirements.