Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: All-optical measurement of high-order fractional molecular echoes by
  high-order harmonic generation   An all-optical measurement of high-order fractional molecular echoes is
demonstrated by using high-order harmonic generation (HHG). Excited by a pair
of time-delayed short laser pulses, the signatures of full and high order
fractional (1/2 and 1/3) alignment echoes are observed in the HHG signals
measured from CO2 molecules at various time delays of the probe pulse. By
increasing the time delay of the pump pulses, much higher order fractional
(1/4) alignment echo is also observed in N2O molecules. With an analytic model
based on the impulsive approximation, the spatiotemporal dynamics of the echo
process are retrieved from the experiment. Compared to the typical molecular
alignment revivals, high-order fractional molecular echoes are demonstrated to
dephase more rapidly, which will open a new route towards the ultrashort-time
measurement. The proposed HHG method paves an efficient way for accessing the
high-order fractional echoes in molecules.

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The categories of this paper are: chem-ph
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The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
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The categories of this paper are: quant-ph
14
The categories of this paper are: math-ph
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
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The categories of this paper are: eess
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
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The categories of this paper are: q-alg
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The categories of this paper are: comp-gas
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The categories of this paper are: dg-ga
5
The categories of this paper are: gr-qc