Prospects for Two-Photon Optical Magnetometry

The $^1S_0 \rightarrow$ $^3D_2$ two-photon transition has been driven in an atomic ytterbium vapor using a pair of degenerate photons at 808 nm. Population in the excited state was detected via the $^3D_2 \rightarrow$ $^3P_1$ $\rightarrow$ $^1S_0$ cascade decay, which emits photons at 1479 nm and 556 nm, respectively. For Yb isotopes with nuclear spin, e.g. $^{171}$Yb with I=$\frac{1}{2}$, the transition rate is sensitive to the nuclear spin orientation and the laser polarization, which allows for possibility of performing two-photon optical magnetometry using the nuclear spin of a closed shell atom in its electronic ground state. While there are sufficiently accessible one-photon transitions in Yb to perform single-photon optical magnetometry, our technique generalizes to the noble gases, e.g. $^{129}$Xe with I=$\frac{1}{2}$, where reading out the ground state nuclear spin orientation is significantly more challenging. Relevance to ongoing permanent electric dipole moment experiments will be discussed.