323 research outputs found

    Experimental Quantum Teleportation with a 3-Bell-state Analyzer

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    We present a Bell-state analyzer for time-bin qubits allowing the detection of three out of four Bell-states with linear optics, two detectors and no auxiliary photons. The theoretical success rate of this scheme is 50%. A teleportation experiment was performed to demonstrate its functionality. We also present a teleportation experiment with a Fidelity larger than the cloning limit of F=5/6.Comment: 11 pages, 14 figure

    Long distance entanglement swapping with photons from separated sources

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    We report the first experimental realization of entanglement swapping over large distances in optical fibers. Two photons separated by more than two km of optical fibers are entangled, although they never directly interacted. We use two pairs of time-bin entangled qubits created in spatially separated sources and carried by photons at telecommunication wavelengths. A partial Bell state measurement is performed with one photon from each pair which projects the two remaining photons, formerly independent onto an entangled state. A visibility high enough to violate a Bell inequality is reported, after both photons have each travelled through 1.1 km of optical fiber.Comment: 4 pages, 3 figures, submitte

    Quantum Teleportation with a 3-Bell-state Analyzer

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    We present a novel Bell-state analyzer for time-bin qubits allowing the detection of three out of four Bell-states with linear optics, only two detectors and no auxiliary photons. The theoretical success rate of this scheme is 50%. A teleportation experiment was performed to demonstrate its functionality. We also present a teleportation experiment with a fidelity larger than the cloning limit.Comment: 4 pages, 6 figure

    Statistical models for quantifying diagnostic accuracy with multiple lesions per patient

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    We propose random-effects models to summarize and quantify the accuracy of the diagnosis of multiple lesions on a single image without assuming independence between lesions. The number of false-positive lesions was assumed to be distributed as a Poisson mixture, and the proportion of true-positive lesions was assumed to be distributed as a binomial mixture. We considered univariate and bivariate, both parametric and nonparametric mixture models. We applied our tools to simulated data and data of a study assessing diagnostic accuracy of virtual colonography with computed tomography in 200 patients suspected of having one or more polyps

    Teelt van mais op klei-op-veengrond. Bemesting en grondbewerking

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    rapport bevat de resultaten van veldproeven op het gebied van bemesting en grondbewerking, die in de periode 1997-1999 door proefbedrijf Zegveld van het Praktijkonderzoek Rundvee, Schapen en Paarden (PR) zijn uitgevoerd

    Controlled Quantum Secret Sharing

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    We present a new protocol in which a secret multiqubit quantum state âˆŁÎšâŸ©\ket{\Psi} is shared by nn players and mm controllers, where âˆŁÎšâŸ©\ket{\Psi} is the encoding state of a quantum secret sharing scheme. The players may be considered as field agents responsible for carrying out a task, using the secret information encrypted in âˆŁÎšâŸ©\ket{\Psi}, while the controllers are superiors who decide if and when the task should be carried out and who to do it. Our protocol only requires ancillary Bell states and Bell-basis measurements.Comment: 6 pages, 0 figure, RevTeX4; published version with minor change

    Space-like Separation in a Bell Test assuming Gravitationally Induced Collapses

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    We report on a Bell experiment with space-like separation assuming that the measurement time is related to gravity-induced state reduction. Two energy-time entangled photons are sent through optical fibers and directed into unbalanced interferometers at two receiving stations separated by 18 km. At each station, the detection of a photon triggers the displacement of a macroscopic mass. The timing ensures space-like separation from the moment a photon enters its interferometer until the mass has moved. 2-photon interference fringes with a visibility of up to 90.5% are obtained, leading to a violation of Bell inequality

    Multivariate random effects meta-analysis of diagnostic tests with multiple thresholds

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    Background. Bivariate random effects meta-analysis of diagnostic tests is becoming a well established approach when studies present one two-by-two table or one pair of sensitivity and specificity. When studies present multiple thresholds for test positivity, usually meta-analysts reduce the data to a two-by-two table or take one threshold value at a time and apply the well developed meta-analytic approaches. However, this approach does not fully exploi
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