Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A tunable CW UV laser with <35 kHz absolute frequency instability for
  precision spectroscopy of Sr Rydberg states   We present a solid-state laser system that generates over 200 mW of
continuous-wave, narrowband light, tunable from 316.3 nm - 317.7 nm and 318.0
nm - 319.3 nm. The laser is based on commercially available fiber amplifiers
and optical frequency doubling technology, along with sum frequency generation
in a periodically poled stoichiometric lithium tantalate crystal. The laser
frequency is stabilized to an atomic-referenced high finesse optical transfer
cavity. Using a GPS-referenced optical frequency comb we measure a long term
frequency instability of $<$35 kHz for timescales between $10^{-3}$ s and
$10^3$ s. As an application we perform spectroscopy of Sr Rydberg states from
$n$ = 37 - 81, demonstrating mode-hop-free scans of 24 GHz. In a cold atomic
sample we measure Doppler-limited linewidths of 350 kHz.

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The categories of this paper are: math
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The categories of this paper are: chao-dyn
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The categories of this paper are: cond-mat
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-ex
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The categories of this paper are: quant-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
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The categories of this paper are: econ
30
The categories of this paper are: q-alg
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The categories of this paper are: dg-ga
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The categories of this paper are: comp-gas
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The categories of this paper are: solv-int
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The categories of this paper are: cmp-lg
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The categories of this paper are: nlin