Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Introduction to attosecond time-delays in photoionization   This tutorial presents an introduction to the interaction of light and matter
on the attosecond timescale. Our aim is to detail the theoretical description
of ultra-short time-delays, and to relate these to the phase of extreme
ultraviolet (XUV) light pulses and to the asymptotic phase-shifts of
photoelectron wave packets. Special emphasis is laid on time-delay experiments,
where attosecond XUV pulses are used to photoionize target atoms at
well-defined times, followed by a probing process in real time by a
phase-locked, infrared laser field. In this way, the laser field serves as a
"clock" to monitor the ionization event, but the observable delays do not
correspond directly to the delay associated with single-photon ionization.
Instead, a significant part of the observed delay originates from a measurement
induced process, which obscures the single-photon ionization dynamics. This
artifact is traced back to a phase-shift of the above-threshold ionization
transition matrix element, which we call the continuum-continuum phase. It
arises due to the laser-stimulated transitions between Coulomb continuum
states. As we shall show here, these measurement-induced effects can be
separated from the single-photon ionization process, using analytical
expressions of universal character, so that eventually the attosecond
time-delays in photoionization can be accessed.

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The categories of this paper are: dg-ga
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The categories of this paper are: solv-int
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The categories of this paper are: ao-sci
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The categories of this paper are: cmp-lg
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: q-bio
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The categories of this paper are: alg-geom
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The categories of this paper are: math-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: bayes-an
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The categories of this paper are: acc-phys
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The categories of this paper are: supr-con
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The categories of this paper are: mtrl-th
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The categories of this paper are: plasm-ph