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Phys. Rev. A 62, 032307 (2000) [9 pages]

Fidelity and concurrence of conjugated states

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Armin Uhlmann
Institut für Theoretische Physik, Universität Leipzig, D-04109 Leipzig, Germany

Received 11 October 1999; published 16 August 2000

We prove some properties of fidelity (transition probability) and concurrence, the latter defined by a straightforward extension of Wootters’ notation. Choose a conjugation and consider the dependence of fidelity or of concurrence on conjugated pairs of density operator. These functions turn out to be concave or convex roofs. Optimal decompositions are constructed. Some applications to two and tripartite systems illustrate the general theorems.


©2000 The American Physical Society

URL: http://link.aps.org/doi/10.1103/PhysRevA.62.032307
DOI: 10.1103/PhysRevA.62.032307
PACS: 03.67.-a, 03.65.Bz, 89.70.+c

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