Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A simple, narrow, and robust atomic frequency reference at 993 nm
  exploiting the rubidium (Rb) $5\mathit{S}_{1/2}$ to $6\mathit{S}_{1/2}$
  transition using one-color two-photon excitation   We experimentally demonstrate a one-color two-photon transition from the
$5\mathit{S}_{1/2}$ ground state to the $6\mathit{S}_{1/2}$ excited state in
rubidium (Rb) vapor using a continuous wave laser at 993 nm. The Rb vapor
contains both isotopes ($^{85}$Rb and $^{87}$Rb) in their natural abundances.
The electric dipole allowed transitions are characterized by varying the power
and polarization of the excitation laser. Since the optical setup is relatively
simple, and the energies of the allowed levels are impervious to stray magnetic
fields, this is an attractive choice for a frequency reference at 993 nm, with
possible applications in precision measurements and quantum information
processing.

24
The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
18
The categories of this paper are: econ
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
2
The categories of this paper are: math
35
The categories of this paper are: mtrl-th
20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
6
The categories of this paper are: astro-ph
16
The categories of this paper are: stat
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an