Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Two-color photoionization of calcium using SHG and LED light   We present a photoionization method to load single 40Ca ions in a linear Paul
trap from an atomic beam. Neutral Ca I atoms are resonantly excited from the
ground state to the intermediate 4s4p 1P_1-level using coherent 423nm radiation
produced by single-pass second harmonic generation in a periodically poled
KTiOPO_4 crystal pumped with an 120mW extended cavity diode laser. Ionization
is then attained with a high-power light emitting diode imaged to the trap
center, using an appropriately designed optical system composed of standard
achromatic doublet lenses. The setup simplifies previous implementations at
similar efficiency, and it hardly requires any maintenance at all.

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The categories of this paper are: hep-th
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The categories of this paper are: hep-ex
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The categories of this paper are: gr-qc
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The categories of this paper are: nucl-ex
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The categories of this paper are: bayes-an
32
The categories of this paper are: atom-ph
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The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph
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The categories of this paper are: math
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The categories of this paper are: nlin
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The categories of this paper are: acc-phys
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The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg
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The categories of this paper are: astro-ph
30
The categories of this paper are: q-alg
35
The categories of this paper are: mtrl-th