Excitation of E1-forbidden atomic transitions with electric, magnetic, or mixed multipolarity in light fields carrying orbital and spin angular momentum [Invited]

Abstract

Photons carrying a well-defined orbital angular momentum have been proven to modify spectroscopic selection rules in atomic matter. Excitation profiles of electric quadrupole transitions have been measured with single trapped 40 Ca ions for varying polarizations. We further develop the photo-absorption formalism to study the case of arbitrary alignment of the beam’s optical axis with respect to the ion’s quantization axis and mixed multipolarity. Thus, predictions for M 1-dominated 40 Ar 13 , E3-driven 171 Yb and 172 Yb, and B-like 20 Ne 5 are presented. The latter case displays novel effects, coming from the presence of a strong photon–magnetic dipole coupling.