Acín dal Maschio, AntonioTarrach, R., 1948-Vidal Bonafont, Guifré2009-10-062009-10-0620001050-2947https://hdl.handle.net/2445/9563We present optimal measuring strategies for an estimation of the entanglement of unknown two-qubit pure states and of the degree of mixing of unknown single-qubit mixed states, of which N identical copies are available. The most general measuring strategies are considered in both situations, to conclude in the first case that a local, although collective, measurement suffices to estimate entanglement, a nonlocal property, optimally.8 p.application/pdfeng(c) The American Physical Society, 2000Teoria de la informacióTeoria quànticaInformation theoryQuantum theoryinfo:eu-repo/semantics/article189681info:eu-repo/semantics/openAccess