Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electromagnetically induced transparency and four-wave mixing in a cold
  atomic ensemble with large optical depth   We report on the delay of optical pulses using electromagnetically induced
transparency in an ensemble of cold atoms with an optical depth exceeding 500.
To identify the regimes in which four-wave mixing impacts on EIT behaviour, we
conduct the experiment in both rubidium 85 and rubidium 87. Comparison with
theory shows excellent agreement in both isotopes. In rubidium 87, negligible
four-wave mixing was observed and we obtained one pulse-width of delay with 50%
efficiency. In rubidium 85, four-wave-mixing contributes to the output. In this
regime we achieve a delay-bandwidth product of 3.7 at 50% efficiency, allowing
temporally multimode delay, which we demonstrate by compressing two pulses into
the memory medium.

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The categories of this paper are: mtrl-th
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The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
16
The categories of this paper are: stat
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The categories of this paper are: supr-con
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The categories of this paper are: patt-sol
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The categories of this paper are: alg-geom
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The categories of this paper are: solv-int
3
The categories of this paper are: physics
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The categories of this paper are: q-alg
1
The categories of this paper are: cs
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The categories of this paper are: astro-ph
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The categories of this paper are: hep-th
4
The categories of this paper are: cond-mat
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The categories of this paper are: nlin
11
The categories of this paper are: hep-lat