Separable measurement estimation of density matrices and its fidelity gap with collective protocols
Bagán Capella, Emili (Universitat Autònoma de Barcelona. Departament de Física)
Ballester, M. A. (Centrum voor Wiskunde en Informatica (Amsterdam, Països Baixos))
Gill, R. D. (University of Leiden. Department of Mathematics)
Muñoz Tapia, Ramon (Universitat Autònoma de Barcelona. Departament de Física)
Romero-Isart, Oriol (Universitat Autònoma de Barcelona. Departament de Física)
American Physical Society

Date:	2006
Abstract:	We show that there exists a gap between the performance of separable and collective measurements in the qubit mixed-state estimation that persists in the large sample limit. We characterize the gap with sharp asymptotic bounds on mean fidelity. We present an adaptive protocol that attains the separable measurement bound. This protocol uses von Neumann measurements and can be easily implemented with current technology.
Rights:	Tots els drets reservats.
Language:	Anglès
Document:	Article ; Versió publicada
Published in:	Physical review letters, Vol. 97, Issue 13 (September 2006) , p. 130501, ISSN 1079-7114

DOI: 10.1103/PhysRevLett.97.130501

4 p, 111.3 KB

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