title: Resource-Efficient Measurement-Device-Independent Entanglement Witness.
abstract: Imperfections in experimental measurement schemes can lead to falsely identifying, or over estimating, entanglement in a quantum system. A recent solution to this is to define schemes that are robust to measurement imperfections-measurement-device-independent entanglement witness (MDI-EW). This approach can be adapted to witness all entangled qubit states for a wide range of physical systems and does not depend on detection efficiencies or classical communication between devices. Here we extend the theory to remove the necessity of prior knowledge about the two-qubit states to be witnessed. Moreover, we tested this model via a novel experimental implementation for MDI-EW that significantly reduces the experimental complexity. By applying it to a bipartite Werner state, we demonstrate the robustness of this approach against noise by witnessing entanglement down to an entangled state fraction close to 0.4.
authors.affiliation: Group of Applied Physics, University of Geneva, 1211 Geneva, Switzerland.
authors.forename: E
authors.initials: E
authors.lastname: Verbanis
authors.affiliation: Group of Applied Physics, University of Geneva, 1211 Geneva, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Martin
authors.affiliation: Group of Applied Physics, University of Geneva, 1211 Geneva, Switzerland.
authors.forename: D
authors.initials: D
authors.lastname: Rosset
authors.affiliation: Group of Applied Physics, University of Geneva, 1211 Geneva, Switzerland.|Quantum Information Science Group, Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6418, USA.
authors.forename: C C W
authors.initials: CC
authors.lastname: Lim
authors.affiliation: Group of Applied Physics, University of Geneva, 1211 Geneva, Switzerland.
authors.forename: R T
authors.initials: RT
authors.lastname: Thew
authors.affiliation: Group of Applied Physics, University of Geneva, 1211 Geneva, Switzerland.
authors.forename: H
authors.initials: H
authors.lastname: Zbinden