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Extremal covariant quantum operations and POVM's

Giacomo Mauro D'Ariano

quant-pharXiv:quant-ph/0310024

Abstract

We consider the convex sets of QO's (quantum operations) and POVM's (positive operator valued measures) which are covariant under a general finite-dimensional unitary representation of a group. We derive necessary and sufficient conditions for extremality, and give general bounds for ranks of the extremal POVM's and QO's. Results are illustrated on the basis of simple examples.

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