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.
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References
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Communicated by L. Rodman.
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© 2010 Birkhäuser Verlag Basel/Switzerland
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Szarek, S.J. (2010). On Norms of Completely Positive Maps. In: Topics in Operator Theory. Operator Theory: Advances and Applications, vol 202. Birkhäuser Basel. https://doi.org/10.1007/978-3-0346-0158-0_31
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DOI: https://doi.org/10.1007/978-3-0346-0158-0_31
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