Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Classical and quantum-mechanical treatments of nonsequential double
  ionization with few-cycle laser pulses   We address nonsequential double ionization induced by strong, linearly
polarized laser fields of only a few cycles, considering a physical mechanism
in which the second electron is dislodged by the inelastic collision of the
first electron with its parent ion. The problem is treated classically, using
an ensemble model, and quantum-mechanically, within the strong-field and
uniform saddle-point approximations. In the latter case, the results are
interpreted in terms of "quantum orbits", which can be related to the
trajectories of a classical electron in an electric field. We obtain highly
asymmetric electron momentum distributions, which strongly depend on the
absolute phase, i.e., on the phase difference between the pulse envelope and
its carrier frequency. Around a particular value of this parameter, the
distributions shift from the region of positive to that of negative momenta, or
vice-versa, in a radical fashion. This behavior is investigated in detail for
several driving-field parameters, and provides a very efficient method for
measuring the absolute phase. Both models yield very similar distributions,
which share the same physical explanation. There exist, however, minor
discrepancies due to the fact that, beyond the region for which electron-impact
ionization is classically allowed, the yields from the quantum mechanical
computation decay exponentially, whereas their classical counterparts vanish.

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The categories of this paper are: cmp-lg
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The categories of this paper are: chao-dyn
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The categories of this paper are: ao-sci
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The categories of this paper are: bayes-an
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The categories of this paper are: adap-org
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The categories of this paper are: eess
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The categories of this paper are: solv-int
5
The categories of this paper are: gr-qc
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The categories of this paper are: chem-ph
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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: econ
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The categories of this paper are: stat
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The categories of this paper are: mtrl-th
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The categories of this paper are: supr-con
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The categories of this paper are: nlin