This is an announcement for the paper "Still more on norms of completely positive maps" by Stanislaw J. Szarek.
Abstract: King and Ruskai asked whether the norm of a completely positive map acting between Schatten classes of operators is equal to that of its restriction to the real subspace of self-adjoint operators. Proofs have been promptly supplied by Watrous and Audenaert. Here we provide one more proof, in fact of a slightly more general fact, under the (slightly weaker) assumption of 2-positivity. The argument is elementary and self-contained.
Archive classification: Quantum Physics; Functional Analysis
Remarks: 2 pages
Submitted from: szarek@cwru.edu
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http://front.math.ucdavis.edu/quant-ph/0603110
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http://arXiv.org/abs/quant-ph/0603110
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