Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Frequency-comb based double-quantum two-dimensional coherent
  spectroscopy identifies collective hyperfine resonances in atomic vapor
  induced by dipole-dipole interactions   Frequency comb based multidimensional coherent spectroscopy is a novel
optical method that enables high resolution measurement in a short acquisition
time. The method's resolution makes multidimensional coherent spectroscopy
relevant for atomic systems that have narrow resonances. We use double-quantum
multidimensional coherent spectroscopy to reveal collective hyperfine
resonances in rubidium vapor at 100 C induced by dipole-dipole interactions. We
observe tilted lineshapes in the double-quantum 2D spectra, which has never
been reported for Doppler-broadened systems. The tilted lineshapes suggest that
the signal is predominately from the interacting atoms that have near zero
relative velocity.

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The categories of this paper are: gr-qc
34
The categories of this paper are: chem-ph
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The categories of this paper are: math-ph
35
The categories of this paper are: mtrl-th
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The categories of this paper are: eess
27
The categories of this paper are: comp-gas
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The categories of this paper are: plasm-ph
32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ
4
The categories of this paper are: cond-mat
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The categories of this paper are: acc-phys
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The categories of this paper are: dg-ga
31
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: hep-th
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The categories of this paper are: q-alg