Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Resonant Processes and Exciton Propagation in a Frozen Gas   We present numerical simulations of a theory of resonant processes in a
frozen gas of excited atoms interacting via dipole-dipole potentials that vary
as $r^{-3}$, where $r$ is the interatomic separation. The simulations calculate
time-dependent averages of transition amplitudes and transition probabilities
for a single atom in a given state interacting resonantly with a uniformly
distributed random gas of atoms in a different state. The averages are over
spatial configurations of the gas atoms, which are held fixed while the
resonant interaction creates a Frenkel exciton that can travel from atom to
atom. We check that the simulations reproduce previously known exact results
when the exciton is not allowed to propagate [Phys. Rev. A 59, 4358 (1999)].
Further, we develop an approximation for the average transition amplitude that
compares well with the numerical results for a wide range of values of the
system parameters.

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The categories of this paper are: hep-th
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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: comp-gas
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: quant-ph
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The categories of this paper are: q-alg
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The categories of this paper are: stat
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The categories of this paper are: adap-org
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The categories of this paper are: dg-ga
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The categories of this paper are: plasm-ph
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The categories of this paper are: math
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The categories of this paper are: acc-phys
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The categories of this paper are: supr-con