Extensions of Perturbation Theory for Spin Dressed Neutrons and 3He Comagnetometers in Superfluid 4He

The nEDM experiment at Oak Ridge’s Spallation Neutron Source will probe for an electric dipole moment of the neutron at an unprecedented level of sensitivity. Polarized 3He atoms dressed by a radio-frequency field are a crucial component. For field parameters comparable to the parameters being used in the nEDM experiment, numerical studies using a fourth-order Runge-Kutta solver reveal inadequacies in earlier analyses of 3He spin dynamics. It’s seen that neutron absorption is influenced by avoided level-crossings omitted previously. Also, the critical dressing condition, used to eliminate effects of the static magnetic field, requires modification. First-order perturbative corrections to eigenstates and third-order corrections to eigenenergies are needed to account for the impact of avoided level-crossings and the changes in the critical dressing condition, respectively.