A quantum channel with additive minimum output entropy

2004/03/09 by Nilanjana Datta, Datta, Nilanjana, Alexander S. Holevo +3
Physics and Astronomy · #FOS: Physical sciences #Quantum Physics (quant-ph) #quant-ph

paper · pdf · doi:10.48550/arxiv.quant-ph/0403072

15 pages, 2 figures

arxiv created 2004/03/09 · arxiv updated 2009/12/01

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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