Separable measurement estimation of density matrices and its fidelity gap with collective protocols

E. Bagan, M.A. Ballester Sánchez, R.D. Gill, R. Muñoz-Tapia, O. Romero-Isart

Research output: Contribution to journalArticleAcademicpeer-review

36 Citations (Scopus)
127 Downloads (Pure)

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.
Original languageEnglish
Article number130501
Pages (from-to)130501-1/4
JournalPhysical Review Letters
Volume97
Issue number13
DOIs
Publication statusPublished - 2006

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