Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Two-way Gaussian quantum cryptography against coherent attacks in direct
  reconciliation   We consider the two-way quantum cryptographic protocol with coherent states
assuming direct reconciliation. A detailed security analysis is performed
considering a two-mode coherent attack, that represents the residual
eavesdropping once the parties have reduced the general attack by applying
symmetric random permutations. In this context we provide a general analytical
expression for the keyrate, discussing the impact of the residual two-mode
correlations on the security of the scheme. In particular we identify the
optimal eavesdropping against two-way quantum communication, which is given by
a two-mode coherent attack with symmetric and separable correlations.

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The categories of this paper are: comp-gas
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The categories of this paper are: bayes-an
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The categories of this paper are: astro-ph
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The categories of this paper are: hep-th
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The categories of this paper are: patt-sol
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The categories of this paper are: supr-con
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The categories of this paper are: solv-int
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The categories of this paper are: q-alg
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The categories of this paper are: cmp-lg
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The categories of this paper are: eess
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The categories of this paper are: nlin
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The categories of this paper are: cond-mat
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The categories of this paper are: ao-sci
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The categories of this paper are: atom-ph
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The categories of this paper are: adap-org
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The categories of this paper are: plasm-ph