title: Novel schemes for directly measuring entanglement of general states.
abstract: An intrinsic relation between maximally entangled states and entanglement measures is revealed, which plays a role in establishing connections for different entanglement quantifiers. We exploit the basic idea and propose a framework to construct schemes for directly measuring entanglement of general states. In particular, we demonstrate that rank-1 local factorizable projective measurements, which are achievable with only one copy of an entangled state involved at a time in a sequential way, are sufficient to directly determine the concurrence of an arbitrary two-qubit entangled state.
authors.affiliation: Institut für Theoretische Physik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria. Jian.Cai@uibk.ac.at
authors.forename: Jianming
authors.initials: J
authors.lastname: Cai
authors.forename: Wei
authors.initials: W
authors.lastname: Song