Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ionization and excitation of low-lying circular states of the hydrogen
  atom in strong circularly polarized laser fields   We perform ab initio calculations for the hydrogen atom initially in one of
the six circular bound states with the principal quantum numbers n = 2, 3 and
4, irradiated by a short circularly polarized laser pulse of 400 nm. The field
propagates in the direction parallel to the z-component of the angular momentum
of the atom. We investigate probabilities for the atom to ionize or to get on
some bound (excited) state or to remain in the initial state after the end of
the laser pulse. In most cases, we find pronounced differences in ionization
probabilities for atoms in states having different signs of magnetic quantum
number. Usually electrons corotating (with respect to the laser field) ionize
faster than their counter-rotating equivalents. We have found important
difference in the behavior of the excitation (as a function of the peak laser
intensity) for initial states with n = 2 and other n (3 or 4). For higher n the
excitation is always weaker than the ionization and starts for higher
intensities. For n = 2 the strong excitation appears before strong ionization
due to large probability of one-photon absorption combined with population of
many bound states having principal quantum numbers n from 3 up to several
dozen. Quite accurate analysis of the excitation process is presented.

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The categories of this paper are: comp-gas
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The categories of this paper are: q-alg
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The categories of this paper are: hep-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: supr-con
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The categories of this paper are: eess
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The categories of this paper are: plasm-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: math-ph
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The categories of this paper are: adap-org
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The categories of this paper are: stat
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The categories of this paper are: chao-dyn
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The categories of this paper are: bayes-an
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The categories of this paper are: alg-geom
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The categories of this paper are: dg-ga
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The categories of this paper are: gr-qc