Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Simultaneous two-photon resonant optical laser locking (STROLLing) in
  the hyperfine Paschen--Back regime   We demonstrate a technique to lock simultaneously two laser frequencies to
each step of a two-photon transition in the presence of a magnetic field
sufficiently large to gain access to the hyperfine Paschen-Back regime. A
ladder configuration with the 5S$_{1/2}$, 5P$_{3/2}$ and 5D$_{5/2}$ terms in a
thermal vapour of $^{87}$Rb atoms is used. The two lasers remain locked for
more than 24 hours. For the sum of the laser frequencies, which represents the
stability of the two-photon lock, we measure a frequency instability of less
than the Rb D$_2$ natural linewidth of 6 MHz for nearly all measured time
scales

28
The categories of this paper are: alg-geom
21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
5
The categories of this paper are: gr-qc
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
16
The categories of this paper are: stat
29
The categories of this paper are: funct-an
25
The categories of this paper are: patt-sol
6
The categories of this paper are: astro-ph
12
The categories of this paper are: nucl-th
33
The categories of this paper are: plasm-ph
32
The categories of this paper are: atom-ph
7
The categories of this paper are: hep-th
22
The categories of this paper are: chao-dyn
8
The categories of this paper are: hep-ex