1,189 research outputs found

    Many-Body Entanglement in Short-Range Interacting Fermi Gases for Metrology

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    We explore many-body entanglement in spinful Fermi gases with short-range interactions, for metrology purposes. We characterize the emerging quantum phases via Density-Matrix Renormalization Group simulations and quantify their entanglement content for metrological usability via the Quantum Fisher Information (QFI). Our study establishes a method, promoting the QFI to be an order parameter. Short-range interactions reveal to build up metrologically promising entanglement in the XY-ferromagnetic and cluster ordering, the cluster physics being unexplored so far.Comment: 5 pages, 4 figures + 10 pages, 8 figures of supplementa

    Output from Bose condensates in tunnel arrays: the role of mean-field interactions and of transverse confinement

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    We present numerical studies of atomic transport in 3D and 1D models for a mode-locked, pulsed atom laser as realized by Anderson and Kasevich [Science 281 (1998) 1686] using an elongated Bose condensate of 87{}^{87}Rb atoms poured into a vertical optical lattice. From our 3D results we ascertain in a quantitative manner the role of mean-field interactions in determining the shape and the size of the pulses in the case of Gaussian transverse confinement. By comparison with 1D simulations we single out a best-performing 1D reduction of the mean-field interactions, which yields quantitatively useful predictions for all main features of the matter output.Comment: 12 pages, 2 figure

    Time-Dependent Density-Functional Theory for Superfluids

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    A density-functional theory is established for inhomogeneous superfluids at finite temperature, subject to time-dependent external fields in isothermal conditions. After outlining parallelisms between a neutral superfluid and a charged superconductor, Hohenberg-Kohn-Sham-type theorems are proved for gauge-invariant densities and a set of Bogolubov-Popov equations including exchange and correlation is set up. Earlier results applying in the linear response regime are recovered.Comment: 12 pages. Europhysics Letters, in pres

    Collective excitations of a periodic Bose condensate in the Wannier representation

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    We study the dispersion relation of the excitations of a dilute Bose-Einstein condensate confined in a periodic optical potential and its Bloch oscillations in an accelerated frame. The problem is reduced to one-dimensionality through a renormalization of the s-wave scattering length and the solution of the Bogolubov - de Gennes equations is formulated in terms of the appropriate Wannier functions. Some exact properties of a periodic one-dimensional condensate are easily demonstrated: (i) the lowest band at positive energy refers to phase modulations of the condensate and has a linear dispersion relation near the Brillouin zone centre; (ii) the higher bands arise from the superposition of localized excitations with definite phase relationships; and (iii) the wavenumber-dependent current under a constant force in the semiclassical transport regime vanishes at the zone boundaries. Early results by J. C. Slater [Phys. Rev. 87, 807 (1952)] on a soluble problem in electron energy bands are used to specify the conditions under which the Wannier functions may be approximated by on-site tight-binding orbitals of harmonic- oscillator form. In this approximation the connections between the low-lying excitations in a lattice and those in a harmonic well are easily visualized. Analytic results are obtained in the tight-binding scheme and are illustrated with simple numerical calculations for the dispersion relation and semiclassical transport in the lowest energy band, at values of the system parameters which are relevant to experiment.Comment: 20 pages, 2 figures, 22 reference

    Probing the energy bands of a Bose-Einstein condensate in an optical lattice

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    We simulate three experimental methods which could be realized in the laboratory to probe the band excitation energies and the momentum distribution of a Bose-Einstein condensate inside an optical lattice. The values of the excitation energies obtained in these different methods agree within the accuracy of the simulation. The meaning of the results in terms of density and phase deformations is tested by studying the relaxation of a phase-modulated condensate towards the ground state.Comment: 5 pages, 5 figure

    Rosemary extract (Rosmarinus officinalis L.) supplementation into the diet of Nero Siciliano pigs: effects on lipid oxidation

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    During the growing-fattening period (93 days; ILW 33.5±6 kg to FLW 67±3 kg), 30 Nero Siciliano pigs were fed on a basal diet supplemented with (ROX group) or not (CTR group) a rosemary extract (1g?kg-1). At 1, 3 and 5 days after slaughtering, the oxidative stability of the Longissimus dorsi muscle was determined by using TBArs test. Moreover, on the individual samples of the muscle the lipid content, the fatty acid and the sterol composition were determined; the acidic composition of the lard, removed from backfat, was also studied. Data were subjected to ANOVA. The fat content of the muscle was unaffected by the dietary treatment as well as the oxidative stability whereas, significant differences (P²0.01) were observed for the polyunsaturated fatty acid content which showed the highest values in the meat as well as in the lard of the ROX group; PUFA/SFA ratio was also significantly highest in the muscle (P=0.004) and in the lard (P=0.017) of the ROX group, testifying a possible antioxidative activity of the rosemary extract. The sterol fraction (cholesterol, cholestanol, stigmasterol, beta-sitosterol and delta 5-avenasterol) of the Longissimus dorsi muscle was unaffected by the rosemary supplementation; a significant difference was observed only for the campesterol (CTR group=1.08, ROX group=0.90; P = 0.021)

    effects of different nutritional levels on nero siciliano pig performance

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    It is well-known that the productive performance and the carcass and meat characteristics are influenced by genetic factors so as by different environmental conditionings. Among these, the feeding should be considered particularly for the quantitative (nutritional level) and qualitative aspects (different components of the ration) so as for the modality of administration, because of the important correlation between genotype and nutritive requirements

    Screening effects in bipolaron theory and high temperature superconductivity

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    The subject of the book is a study on bipolaron formation in heavily doped and polar materials. The study is applied to the physics of superconducting compounds with high transition temperature

    Effect of production system on growth performances and meat traits of suckling Messinese goat kids

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    The aim of this study was to evaluate the effect of the production system on growth performances and meat quality of suckling Messinese goat kids. At birth, 102 suckling kids were divided into two homogeneous groups for sex and body weight (3.4 kg); animals of the SES group were fed exclusively with spontaneous pasture and kept in the stable during the evening; animals of the ES group were fed exclusively with spontaneous pasture, characterised by the presence of Quercus suber, and kept exclusively outdoors. From birth to weaning, kids were weighed every10 days. At slaughter, carcase yields and meat quality traits on the Longissimus dorsi muscle were studied. Data were subjected to ANOVA. ES group showed the highest final body weight (10.53 kg vs. 9.40 kg; p < .001). As regard the meat traits, ES group showed the lowest final pH (5.63 vs. 5.96; p < .001), the lowest value of Hue (46.24 vs. 62.64; p < .005) and the highest values of cooking loss (ES 25.53% vs. SES 19.60%; p < .05) and shear force (ES 5.04 kg/cm2 vs. SES 3.63 kg/cm2; p < .05). Chemical composition showed similar values in both groups. Meat fatty acid composition showed the highest values of MUFA (45.89% vs. 40.90%; p < .05) and PUFA (0.14% vs. 0.11%; p < .05) and the lowest of ω – 6/ω – 3 ratio (4.89 vs. 6.98; p < .05) and Thrombogenic Index (1.64 vs. 1.98; p < .05) in the ES group. The results confirm the favourable characteristics of goat meat and the relation between the typical production system of goats in the Nebrodi area and their performances.HIGHLIGHTS The production system did not affect the weight of kids at birth, while there were significant differences in kid's performance in relation to the breeding system. The chemical composition of the LD muscle was not affect by the production system. The production system significantly influenced the fatty acid composition of the meat. The meat quality parameters studied reflect the modern guidelines for a healthy diet recommend, that reduce the animal fat consumption, especially if rich in saturated fatty acids, and could be a tool to identify and characterise a product with Protected Designation of Origin (PDO) as 'capretto Messinese'

    Il teatro di Ludovico Ariosto e l'innovazione elisabettiana

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    La tesi vuole indagare le relazioni tra teatro classico, teatro ariosteo del primo Cinquecento e teatro elisabettiano, arrivando ad affermare che le opere teatrali di Ariosto, ed in particolare I Suppositi, furono fondamentali nell'innovazione del teatro prima elisabettiano e poi shakespeariano
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