Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum Phase Transitions and Persistent Currents in Josephson-Junction
  Ladders   In this work we study quantum phase transitions and persistent currents in
capacitively coupled one-dimensional Josephson-junction arrays. We will focus
particularly on the roles of exciton-like pairs in the strong coupling limit in
the presence of external gate charges and magnetic fluxes. We use the numerical
density-matrix renormalization group method for the study in the full range of
values of gate charge and magnetic flux. To clarify the various effects, we
report the pair correlation functions and the exciton densities as welll as the
persistent current.

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The categories of this paper are: mtrl-th
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The categories of this paper are: alg-geom
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The categories of this paper are: gr-qc
1
The categories of this paper are: cs
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The categories of this paper are: econ
3
The categories of this paper are: physics
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The categories of this paper are: comp-gas
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The categories of this paper are: funct-an
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The categories of this paper are: math-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-th
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The categories of this paper are: ao-sci
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The categories of this paper are: astro-ph
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The categories of this paper are: supr-con
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The categories of this paper are: hep-lat
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The categories of this paper are: chao-dyn