Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Cooper-Pair Injection into Quantum Spin Hall Insulators   We theoretically study tunneling of Cooper pairs from a superconductor
spanning a two-dimensional topological insulator strip into its helical edge
states. The coherent low-energy electron-pair tunneling sets off positive
current cross correlations along the edges, which reflect an interplay of two
quantumentanglement processes. Most importantly, superconducting spin pairing
dictates a Cooper pair partitioning into the helical edge liquids, which
transport electrons in opposite directions for opposite spin orientations. At
the same time, Luttinger-liquid correlations fractionalize electrons injected
at a given edge into counterpropagating charge pulses carrying definite
fractions of the elementary electron charge.

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The categories of this paper are: nucl-th
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The categories of this paper are: astro-ph
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The categories of this paper are: physics
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The categories of this paper are: hep-th
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The categories of this paper are: math-ph
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The categories of this paper are: funct-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: nlin
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The categories of this paper are: hep-lat
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The categories of this paper are: solv-int
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The categories of this paper are: cs
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The categories of this paper are: bayes-an
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The categories of this paper are: quant-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: stat
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The categories of this paper are: gr-qc