Twisted light beams, or optical vortices, have been used to drive the circular motion of microscopic particles in optical tweezers and have been shown to generate vortices in quantum gases. Recent studies have established that electric quadrupole interactions can mediate an orbital angular momentum exchange between twisted light and the electronic degrees of freedom of atoms. Here we consider a quadrupole atomic transition mediated by a circularly-polarized optical vortex. We evaluate the transfer rate of the optical angular momentum to a $C{a}^{+}$ ion involving the $4^2{S}_{1∕2}\to 3^2{D}_{5∕2}$ quadrupole transition and explain how the polarization state and the topological charge of the vortex beam determine the selection rules.

扭曲的光束或光学涡流已被用于驱动光镊中微观粒子的圆周运动，并已被证明可在量子气体中产生涡流。最近的研究已经确定，电四极杆相互作用可以调节扭曲光和原子的电子自由度之间的轨道角动量交换。在这里，我们考虑由圆偏振光学涡旋介导的四极原子跃迁。我们评估光学角动量到一个$C{\mathrm{一种}}^{+}$ 离子涉及 $4^2{秒}_{1∕2}\to 3^2{D}_{5∕2}$ 四极跃迁并解释涡旋光束的偏振态和拓扑电荷如何决定选择规则。