FIG. 2.
Measured Z1-mode sensitivity as a function of normalized modulation field amplitude u=Ω0/[(1+ε)ωz], showing comparison with the approximate theoretical response function [Eq. (3)]. The inset depicts the spin dynamics for a z-mode magnetometer. An applied magnetic signal, Bx, rotates the spin polarization into the y-z plane. The oscillating z-field (z-modulation) B0 causes the spin to oscillate along an arc. Maximum sensitivity to Bx is achieved by adjusting B0 to make the arc approximately semicircular. Notice that the x polarization oscillates at frequency ωz and the y polarization oscillates at 2ωz.