Maximal output purity and capacity for asymmetric unital qudit channels

Preprint

12 August 2005

preprint
Published by arXiv in arXiv

Abstract

We consider generalizations of depolarizing channels to maps in which the identity channel is replaced by a convex combinations of unitary conjugations. We show that one can construct unital channels of this type for which the input which achieves maximal output purity is unique. We give conditions under which multiplicativity of the maximal p-norm and additivity of the minimal output entropy. We also show that the Holevo capacity need not equal log d - the minimal entropy as one might expect for a convex combination of unitary conjugations. Conversely, we give examples for which this condition holds, but the channel has no evident covariance properties.

Keywords

MAXIMAL OUTPUT PURITY
UNITARY CONJUGATIONS
CONVEX COMBINATION
QUDIT CHANNELS
OUTPUT PURITY
UNITAL QUDIT
DEPOLARIZING
ENTROPY

All Related Versions

Version 1, 2005-05-08, ArXiv
Version 2, 2005-08-12, ArXiv
Version 3, 2005-08-13, ArXiv
Version 4, 2005-09-15, ArXiv
Published version: Journal of Physics A: General Physics, 38 (45), 9785.

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