Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Doppler-free coherent-control spectroscopy with a colliding pair of
  shaped pulses   We demonstrate the use of the ultrafast spatial coherent-control method to
resolve the fine-structure two-photon transitions of atomic rubidium.
Counter-propagating ultrafast optical pulses with spectral phase and amplitude
programmed with our optimized solutions successfully induced the two-photon
transitions through $5S_{1/2}$-$5P_{1/2}$-$5D$ and $5S_{1/2}$-$5P_{3/2}$-$5D$
pathways, both simultaneously and at distinct spatial locations. Three
different pulse-shaping solutions are introduced that combine amplitude
shaping, which avoids direct intermediate resonances, and phase programming,
which enables the remaining spectral components to be coherently interfered
through the targeted transition pathways. Experiments were performed with a
room-temperature vapor cell, and the results agree well with theoretical
analysis.

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The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
18
The categories of this paper are: econ
10
The categories of this paper are: q-bio
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The categories of this paper are: alg-geom
20
The categories of this paper are: acc-phys
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc
15
The categories of this paper are: nucl-ex
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The categories of this paper are: chem-ph
16
The categories of this paper are: stat
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The categories of this paper are: supr-con
6
The categories of this paper are: astro-ph
12
The categories of this paper are: nucl-th
31
The categories of this paper are: ao-sci