21,144 research outputs found

    One-dimensional description of a Bose-Einstein condensate in a rotating closed-loop waveguide

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    We propose a general procedure for reducing the three-dimensional Schrodinger equation for atoms moving along a strongly confining atomic waveguide to an effective one-dimensional equation. This procedure is applied to the case of a rotating closed-loop waveguide. The possibility of including mean-field atomic interactions is presented. Application of the general theory to characterize a new concept of atomic waveguide based on optical tweezers is finally discussed

    All-Optical Depletion of Dark Excitons from a Semiconductor Quantum Dot

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    Semiconductor quantum dots are considered to be the leading venue for fabricating on-demand sources of single photons. However, the generation of long-lived dark excitons imposes significant limits on the efficiency of these sources. We demonstrate a technique that optically pumps the dark exciton population and converts it to a bright exciton population, using intermediate excited biexciton states. We show experimentally that our method considerably reduces the DE population while doubling the triggered bright exciton emission, approaching thereby near-unit fidelity of quantum dot depletion.Comment: 5 pages, 3 figure

    Statute of Limitations in Cases of Insidious Diseases

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    The industrial revolution and technological development have brought concomitant legal problems unheard of at the common law. Fundamental principles of law evolved to incorporate the changes necessary to rule over a new way of life. Some of the problems of industrialization have been solved, others are in a state of flux, while myriad others are as yet unknown. This article concerns itself with one of the incidents of complex industrial progress-insidious disease, as viewed in the light (or dark) of the statute of limitations

    Prevalence of tick-borne pathogens in Ixodes scapularis in a rural New Jersey County.

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    To assess the potential risk for other tick-borne diseases, we collected 100 adult Ixodes scapularis in Hunterdon County, a rapidly developing rural county in Lyme disease endemic western New Jersey. We tested the ticks by polymerase chain reaction for Borrelia burgdorferi, Babesia microti, and the rickettsial agent of human granulocytic ehrlichiosis (HGE). Fifty-five ticks were infected with at least one of the three pathogens: 43 with B. burgdorferi, five with B. microti, and 17 with the HGE agent. Ten ticks were coinfected with two of the pathogens. The results suggest that county residents are at considerable risk for infection by a tick-borne pathogen after an I. scapularis bite

    Effect of trap symmetry and atom-atom interactions on a trapped atom interferometer with internal state labelling

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    In this paper, we study the dynamics of a trapped atom interferometer with internal state labelling in the presence of interactions. We consider two situations: an atomic clock in which the internal states remain superposed, and an inertial sensor configuration in which they are separated. From the average spin evolution, we deduce the fringe contrast and the phase-shift. In the clock configuration, we recover the well-known identical spin rotation effect (ISRE) which can significantly increase the spin coherence time. We also find that the magnitude of the effect depends on the trap geometry in a way that is consistent with our recent experimental results in a clock configuration [M. Dupont-Nivet, and al., New J. Phys., 20, 043051 (2018)], where ISRE was not observed. In the case of an inertial sensor, we show that despite the spatial separation it is still possible to increase the coherence time by using mean field interactions to counteract asymmetries of the trapping potential.Comment: 18 pages, 5 figure

    Steep sharp-crested gravity waves on deep water

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    A new type of steady steep two-dimensional irrotational symmetric periodic gravity waves on inviscid incompressible fluid of infinite depth is revealed. We demonstrate that these waves have sharper crests in comparison with the Stokes waves of the same wavelength and steepness. The speed of a fluid particle at the crest of new waves is greater than their phase speed.Comment: 4 pages, 2 figures, submitted to Phys. Rev. Let
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