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A quantum channel with additive minimum output entropy

Nilanjana Datta·Alexander S. Holevo·Yuri M. Suhov
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Abstract

We give a direct proof of the additivity of the minimum output entropy of a particular quantum channel which breaks the multiplicativity conjecture. This yields additivity of the classical capacity of this channel, a result obtained by a different method by Matsumoto and Yura [quant-ph/0306009]. Our proof relies heavily upon certain concavity properties of the output entropy which are of independent interest.

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Nilanjana Datta, Alexander S. Holevo, Yuri M. Suhov. 2004-03-09. A quantum channel with additive minimum output entropy. https://arxiv.org/abs/quant-ph/0403072

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