  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 Cs atom involving the $6^2S_{1/2}\rightarrow
5^2D_{5/2}$ quadrupole transition and explain how the polarization state and
the topological charge of the vortex beam determine the selection rules.
