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

    34 Citations (Scopus)
    107 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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