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arXiv:quant-ph/0209085 · Physical Review Letters

One-Qubit Reduced States of a Pure Many-Qubit State: Polygon Inequalities

Atsushi Higuchi, Anthony Sudbery, Jason Szulc

Published Mar 13, 2003• 104 citations
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Abstract

We show that a necessary and sufficient condition for a set of n one-qubit mixed states to be the reduced states of a pure n-qubit state is that their smaller eigenvalues should satisfy polygon inequalities: each of them must be no greater than the sum of the others.
DOI
10.1103/physrevlett.90.107902

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