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Instruments and channels in quantum information theory

Alberto Barchielli·Giancarlo Lupieri
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Abstract

While a positive operator valued measure gives the probabilities in a quantum measurement, an instrument gives both the probabilities and the a posteriori states. By interpreting the instrument as a quantum channel and by using the typical inequalities for the quantum and classical relative entropies, many bounds on the classical information extracted in a quantum measurement, of the type of Holevo's bound, are obtained in a unified manner.

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Alberto Barchielli, Giancarlo Lupieri. 2004-09-03. Instruments and channels in quantum information theory. https://doi.org/10.1134/1.2055938

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