Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Atom-atom entanglement by single-photon detection   A scheme for entangling distant atoms is realized, as proposed in the seminal
paper by Cabrillo et al. [Phys. Rev. A 59, 1025 (1999)]. The protocol is based
on quantum interference and detection of a single photon scattered from two
effectively one meter distant laser-cooled and trapped atomic ions. The
detection of a single photon heralds entanglement of two internal states of the
trapped ions with high rate and with a fidelity limited mostly by atomic
motion. Control of the entangled state phase is demonstrated by changing the
path length of the single-photon interferometer.

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The categories of this paper are: math
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The categories of this paper are: mtrl-th
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The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: econ
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The categories of this paper are: hep-lat
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The categories of this paper are: nucl-ex
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The categories of this paper are: stat
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The categories of this paper are: comp-gas
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The categories of this paper are: supr-con
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The categories of this paper are: acc-phys
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The categories of this paper are: q-alg
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The categories of this paper are: patt-sol
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The categories of this paper are: cmp-lg
26
The categories of this paper are: bayes-an