@article{oai:oist.repo.nii.ac.jp:00001802,
 author = {Rajasree, Krishnapriya Subramonian and Gupta, Ratnesh Kumar and Gokhroo, Vandna and Le Kien, Fam and Nieddu, Thomas and Ray, Tridib and Nic Chormaic, Síle and Tkachenko, Georgiy},
 issue = {3},
 journal = {Physical Review Research},
 month = {Aug},
 note = {We develop a theoretical framework for spin selection in single-frequency two-photon excitation of alkali-metal atoms as a function of polarization of the excitation light. We verify the theory by experimentally probing the [Formula: see text] transition rate in ⁸⁷Rb in two configurations: paraxial light excitation of warm vapor and nonparaxial excitation of laser-cooled atoms. The transition rate follows a quadratic dependence on the helicity parameter linked to the excitation light's polarization. For paraxial excitation, the transition rate scales as the squared degree of linear polarization, being zero for circularly polarized light. In contrast, for nonparaxial excitation via an optical nanofiber, the two-photon transition is not completely extinguished by varying the light polarization. Our findings lead to a deeper and more universal understanding of the physics of multiphoton processes in atoms.},
 title = {Spin selection in single-frequency two-photon excitation of alkali-metal atoms},
 volume = {2},
 year = {2020}
}