Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quadrupole absorption rate for atoms in circularly-polarized optical
  vortices   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 $Ca^+$ ion involving the $4^2S_{1/2}\rightarrow
3^2D_{5/2}$ quadrupole transition and explain how the polarization state and
the topological charge of the vortex beam determine the selection rules.

21
The categories of this paper are: adap-org
4
The categories of this paper are: cond-mat
24
The categories of this paper are: dg-ga
26
The categories of this paper are: bayes-an
2
The categories of this paper are: math
30
The categories of this paper are: q-alg
6
The categories of this paper are: astro-ph
33
The categories of this paper are: plasm-ph
19
The categories of this paper are: eess
27
The categories of this paper are: comp-gas
12
The categories of this paper are: nucl-th
3
The categories of this paper are: physics
1
The categories of this paper are: cs
0
The categories of this paper are: hep-ph
36
The categories of this paper are: cmp-lg
9
The categories of this paper are: nlin