176 research outputs found

    Violation of the Cauchy-Schwarz inequality with matter waves

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    The Cauchy-Schwarz (CS) inequality -- one of the most widely used and important inequalities in mathematics -- can be formulated as an upper bound to the strength of correlations between classically fluctuating quantities. Quantum mechanical correlations can, however, exceed classical bounds.Here we realize four-wave mixing of atomic matter waves using colliding Bose-Einstein condensates, and demonstrate the violation of a multimode CS inequality for atom number correlations in opposite zones of the collision halo. The correlated atoms have large spatial separations and therefore open new opportunities for extending fundamental quantum-nonlocality tests to ensembles of massive particles.Comment: Final published version (with minor changes). 5 pages, 3 figures, plus Supplementary Materia

    Sympathetic Cooling with Two Atomic Species in an Optical Trap

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    We simultaneously trap ultracold lithium and cesium atoms in an optical dipole trap formed by the focus of a CO2_2 laser and study the exchange of thermal energy between the gases. The cesium gas, which is optically cooled to 20μ20 \muK, efficiently decreases the temperature of the lithium gas through sympathetic cooling. The measured cross section for thermalizing 133^{133}Cs-7^7Li collisions is 8×10−128 \times 10^{-12} cm2^2, for both species in their lowest hyperfine ground state. Besides thermalization, we observe evaporation of lithium purely through elastic cesium-lithium collisions (sympathetic evaporation).Comment: 4 pages 3 fig

    Multiple micro-optical atom traps with a spherically aberrated laser beam

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    We report on the loading of atoms contained in a magneto-optic trap into multiple optical traps formed within the focused beam of a CO_{2} laser. We show that under certain circumstances it is possible to create a linear array of dipole traps with well separated maxima. This is achieved by focusing the laser beam through lenses uncorrected for spherical aberration. We demonstrate that the separation between the micro-traps can be varied, a property which may be useful in experiments which require the creation of entanglement between atoms in different micro-traps. We suggest other experiments where an array of these traps could be useful.Comment: 10 pages, 3 figure

    All Optical Formation of an Atomic Bose-Einstein Condensate

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    We have created a Bose-Einstein condensate of 87Rb atoms directly in an optical trap. We employ a quasi-electrostatic dipole force trap formed by two crossed CO_2 laser beams. Loading directly from a sub-doppler laser-cooled cloud of atoms results in initial phase space densities of ~1/200. Evaporatively cooling through the BEC transition is achieved by lowering the power in the trapping beams over ~ 2 s. The resulting condensates are F=1 spinors with 3.5 x 10^4 atoms distributed between the m_F = (-1,0,1) states.Comment: 4 pages, 4 figures, to appear in Phys. Rev. Let

    The Intrinsic Quantum Excitations of Low Temperature Glasses

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    Several puzzling regularities concerning the low temperature excitations of glasses are quantitatively explained by quantizing domain wall motions of the random first order glass transition theory. The density of excitations agrees with experiment and scales with the size of a dynamically coherent region at TgT_g, being about 200 molecules. The phonon coupling depends on the Lindemann ratio for vitrification yielding the observed universal relation l/λ≃150l/\lambda \simeq 150 between phonon wavelength λ\lambda and mean free path ll. Multilevel behavior is predicted to occur in the temperature range of the thermal conductivity plateau.Comment: 4 pages, submitted to PR

    The granite‑hosted Variscan gold deposit from Santo António mine in the Iberian Massif (Penedono, NW Portugal): constraints from mineral chemistry, fuid inclusions, sulfur and noble gases isotopes

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    The study area is located in the Central Iberian Zone, a major tectonic unit of the Iberian Massif (Variscan belt). In this region the basement is composed of Cambrian-Ordovician sedimentary and minor volcanic rocks that underwent deformation and metamorphism during the Carboniferous. These metamorphic rocks host ca. 331–308 Ma granitic plutons emplaced during the D2 extensional and D3–D4 contractional deformation phases. The gold-bearing quartz veins from the Santo António mine (Penedono region) occur in granite formed at 310.1 ± 1.1 Ma and post-dated the peak of metamorphism. Gold–silver alloy is included in quartz, but mainly occurs in spaces between grains or micro-fractures within arsenopyrite of all three generations and less in pyrite. Late sulphides and sulphosalts were deposited along fractures mainly in arsenopyrite, and locally surrounding the gold–silver alloy grains. Ferberite, scheelite and stolzite replace arsenopyrite. The abundant aqueous carbonic fluids and the occurrence of a low-salinity fluid and their minimum possible entrapment temperature of 360–380 °C suggest that this gold-forming event began during the waning stages of the Variscan orogeny. The mean δ34S values of arsenopyrite and pyrite are − 4.7‰ and − 3.8‰, respectively. He–Ar–Ne isotopic data suggest a crustal origin. The ascent of the granite magma has provided the heat for remobilization of gold, other metals and metalloids from the metamorphic rocks. This gold-arsenopyrite deposit has thus similar characteristics as other selected gold-arsenopyrite deposits from the Iberian Massif, but it contains tungstates.El área de estudio está ubicada en la Zona Centroibérica, una importante unidad tectónica del Macizo Ibérico (cinturón varisco). En esta región el basamento está compuesto por rocas sedimentarias y volcánicas del Cámbrico-Ordovícico tectonizadas y metamorfzadas durante el Carbonífero. Estas rocas metamórfcas sirven como caja de los plutones graníticos datados en torno a 331–308 Ma y que fueron emplazados durante la fase de deformación extensional D2 y las fases de deformación contraccional D3 y D4. Las venas de cuarzo ricas en oro de la mina de Santo António (región de Penedono) que aparecen en un granito datado a los 310.1 ± 1.1 Ma son posteriores al pico metamórfco regional. La aleación de oro y plata se incluye en el cuarzo, pero se produce principalmente en los espacios entre granos o micro-fracturas dentro de arsenopirita de las tres generaciones y menos en pirita. Los sulfuros y sulfuros tardíos se depositaron a lo largo de las fracturas principalmente en arsenopirita, y alrededor de los granos de aleación de oro y plata. Ferberita, scheelita y la estolzita sustituyen a la arsenopirita. Los abundantes líquidos acuosos carbónicos y la presencia de un fuido de baja salinidad y su posible temperatura de atrapamiento mínima en torno de 360-380 ºC sugieren que este evento de formación de oro comenzó durante las etapas fnales de la orogenia varisca. Los valores medios de S de arsenopirita y pirita son − 4.7 ‰ y − 3.8 ‰, respectivamente. Los datos isotópicos de He–Ar–Ne sugieren que en el origen de los fuidos mineralizados participa la corteza continental. El ascenso del magma granítico ha provisto el calor para la movilización del oro, otros metales y metaloides desde las rocas metamórfcas. Este depósito de oroarsenopirita tiene así características similares a otros yaciamientos con arsenopirita y oro del Macizo Ibérico, pero sin embargo contienen tungstates.This research was financially supported by Fundação para a Ciência e Tecnologia through the projects GOLDGranites, Orogenesis, Long-term strain/stress and Deposition of ore metals—PTDC/GEO-GEO/2446/2012: COMPETE: FCOMP-01-0124-FEDER-029192 and UID/GEO/04035/2013

    Cold and trapped metastable noble gases

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    We review experimental and theoretical work on cold, trapped metastable noble gases. We em- phasize the aspects which distinguish work with these atoms from the large body of work on cold, trapped atoms in general. These aspects include detection techniques and collision processes unique to metastable atoms. We describe several experiments exploiting these unique features in fields including atom optics and statistical physics. We also discuss precision measurements on these atoms including fine structure splittings, isotope shifts, and atomic lifetimes

    Comparative efficacy of two microdoses of a potentized homoeopathic drug, Cadmium Sulphoricum, in reducing genotoxic effects produced by cadmium chloride in mice: a time course study

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    BACKGROUND: Cadmium poisoning in the environment has assumed an alarming problem in recent years. Effective antimutagenic agents which can reverse or combat cadmium induced genotoxicity in mice have not yet been reported. Therefore, in the present study, following the homeopathic principle of "like cures like", we tested the efficacy of two potencies of a homeopathic drug, Cadmium Sulphoricum (Cad Sulph), in reducing the genotoxic effects of Cadmium chloride in mice. Another objective was to determine the relative efficacy of three administrative modes, i.e. pre-, post- and combined pre and post-feeding of the homeopathic drugs. For this, healthy mice, Mus musculus, were intraperitoneally injected with 0.008% solution of CdCl(2) @ 1 ml/100 gm of body wt (i.e. 0.8 mcg/gm of bw), and assessed for the genotoxic effects through such studies as chromosome aberrations (CA), micronucleated erythrocytes (MNE), mitotic index (MI) and sperm head anomaly (SHA), keeping suitable succussed alcohol fed (positive) and CdCl(2) untreated normal (negative) controls. The CdCl(2) treated mice were divided into 3 subgroups, which were orally administered with the drug prior to, after and both prior to and after injection of CdCl(2) at specific fixation intervals and their genotoxic effects were analyzed. RESULTS: While the CA, MNE and SHA were reduced in the drug fed series as compared to their respective controls, the MI showed an apparent increase. The combined pre- and post-feeding of Cad Sulph showed maximum reduction of the genotoxic effects. CONCLUSIONS: Both Cad Sulph-30 and 200 were able to combat cadmium induced genotoxic effects in mice and that combined pre- and post-feeding mode of administration was found to be most effective in reducing the genotoxic effect of CdCl(2) followed by the post-feeding mode

    Accumulation of an Antidepressant in Vesiculogenic Membranes of Yeast Cells Triggers Autophagy

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    Many antidepressants are cationic amphipaths, which spontaneously accumulate in natural or reconstituted membranes in the absence of their specific protein targets. However, the clinical relevance of cellular membrane accumulation by antidepressants in the human brain is unknown and hotly debated. Here we take a novel, evolutionarily informed approach to studying the effects of the selective-serotonin reuptake inhibitor sertraline/Zoloft® on cell physiology in the model eukaryote Saccharomyces cerevisiae (budding yeast), which lacks a serotonin transporter entirely. We biochemically and pharmacologically characterized cellular uptake and subcellular distribution of radiolabeled sertraline, and in parallel performed a quantitative ultrastructural analysis of organellar membrane homeostasis in untreated vs. sertraline-treated cells. These experiments have revealed that sertraline enters yeast cells and then reshapes vesiculogenic membranes by a complex process. Internalization of the neutral species proceeds by simple diffusion, is accelerated by proton motive forces generated by the vacuolar H+-ATPase, but is counteracted by energy-dependent xenobiotic efflux pumps. At equilibrium, a small fraction (10–15%) of reprotonated sertraline is soluble while the bulk (90–85%) partitions into organellar membranes by adsorption to interfacial anionic sites or by intercalation into the hydrophobic phase of the bilayer. Asymmetric accumulation of sertraline in vesiculogenic membranes leads to local membrane curvature stresses that trigger an adaptive autophagic response. In mutants with altered clathrin function, this adaptive response is associated with increased lipid droplet formation. Our data not only support the notion of a serotonin transporter-independent component of antidepressant function, but also enable a conceptual framework for characterizing the physiological states associated with chronic but not acute antidepressant administration in a model eukaryote
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