Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ion Crystal Metamorphoses in a Paul trap   The standard second-order pseudo-oscillator potential used in many analytical
investigations of the properties of ions stored in a Paul trap has serious
limitations. In this paper we show that ion-crystal configurations exhibited by
2, 3, and 4 simultaneously stored ions in a Paul trap are not predicted by the
standard pseudo-oscillator potential, but are all captured qualitatively and
quantitatively by an extended pseudopotential derived in this paper. The power
of our extended pseudopotential extends in particular to the prediction of the
border lines between different crystal configurations (morphologies) in the
Paul trap's $a$, $q$ stability diagram. In the three- and four-ion cases,
several of the ion-crystal structures predicted by our improved pseudopotential
have never been observed experimentally before. We present them here as a
challenge for experiments.

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The categories of this paper are: bayes-an
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The categories of this paper are: nlin
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The categories of this paper are: adap-org
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The categories of this paper are: stat
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The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc
10
The categories of this paper are: q-bio
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The categories of this paper are: funct-an
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The categories of this paper are: cmp-lg
2
The categories of this paper are: math
13
The categories of this paper are: quant-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: nucl-th
4
The categories of this paper are: cond-mat
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The categories of this paper are: solv-int
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The categories of this paper are: ao-sci