Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Negative Conditional Entropy of Post-Selected States   We define a quantum entropy conditioned on post-selection which has the von
Neumann entropy of pure states as a special case. This conditional entropy can
take negative values which is consistent with part of a quantum system
containing less information than the whole which can be in a pure state. The
definition is based on generalised density operators for postselected
ensembles. The corresponding density operators are consistent with the quantum
generalisation of classical conditional probabilities following Dirac s
formalism of quasiprobability distributions.

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The categories of this paper are: hep-lat
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The categories of this paper are: hep-ph
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The categories of this paper are: math
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The categories of this paper are: nlin
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-ex
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The categories of this paper are: mtrl-th
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The categories of this paper are: econ
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The categories of this paper are: cond-mat
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The categories of this paper are: comp-gas
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The categories of this paper are: cs
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The categories of this paper are: funct-an
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The categories of this paper are: q-alg
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The categories of this paper are: eess
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The categories of this paper are: patt-sol
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The categories of this paper are: stat