Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Theoretical and Numerical studies of the positions of cold trapped ions   We examine the properties of cold ions confined by a Paul trap in a linear
crystal configuration, a system of considerable current interest due to its
application to practical quantum computation. Using a combination of
theoretical and numerical calculation, a semi- empirical formula for the
positions of the ions is derived.

20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
23
The categories of this paper are: solv-int
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph