1,721,005 research outputs found
Faraday waves in elongated superfluid fermionic clouds
Full text linkWe use hydrodynamic equations to study the formation of Faraday waves in a superfluid Fermi gas at zero temperature confined in a strongly elongated cigar-shaped trap. First, we treat the role of the radial density profile in the limit of an infinite cylindrical geometry and analytically evaluate the wavelength of the Faraday pattern. The effect of the axial confinement is fully taken into account in the numerical solution of hydrodynamic equations, and shows that the infinite cylinder geometry provides a very good description of the phenomena. © 2008 The American Physical Society.Fil: Capuzzi, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Vignolo, P.. Universite Nice; Francia. Centre National de la Recherche Scientifique; Franci
Finite-temperature contact for a SU(2) Fermi gas trapped in a one-dimensional harmonic confinement
No full textWe calculate the finite-temperature Tan's contact for N SU(2) fermions, characterized by repulsive contact interaction, trapped in a 1D harmonic confinement within a local density approximation on top of a thermodynamic Bethe ansatz. The Tan's contact for such a system, as in the homogeneous case, displays a minimum at a very low temperature. By means of an exact canonical ensemble calculation for two fermions, we provide an explicit formula for the contact at very low temperatures that reveals that the minimum is due to the mixing of states with different exchange symmetries. In the unitary regime, this symmetry blending corresponds to a maximal entanglement entropy.Fil: Capuzzi, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Vignolo, P.. Centre National de la Recherche Scientifique; Franci
Vortices in two-component Bose-Einstein condensates
Full text linkWe study the spatial distribution of particles in two-component Bose-Einstein condensates containing vortices. We show that the form in which the species are arranged inside the condensate may be easily understood using simple approximations. We obtain expressions for the location of particular points which are useful for describing the density of particles in two limiting situations, using either the Thomas-Fermi approximation or a low-dilution approximation. A discussion about the shape of vortex cores is also included. © 2005 IOP Publishing Ltd.Fil: Jezek, Dora Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Capuzzi, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentin
Density wave propagation in a two-dimensional random dimer potential: From a single to a bipartite square lattice
Full text linkWe study the propagation of a density perturbation in a weakly interacting boson gas confined on a lattice and in the presence of square dimerized impurities. Such a two-dimensional dual random dimer model (2D DRDM), previously introduced [Capuzzi, Gattobigio, and Vignolo, Phys. Rev. A 92, 053622 (2015)PLRAAN1050-294710.1103/PhysRevA.92.053622], is the disorder transition from a single square lattice, where impurities are absent, to a bipartite square lattice, where the number of impurities is maximum and coincides with half the number of lattice sites. We show that disorder correlations can play a crucial role in the dynamics for a broad range of parameters by allowing density fluctuations to propagate in the 2D DRDM lattice, even in the limit of strong disorder. In such a regime, the propagation speed depends on the percentage of impurities, interpolating between the speed in a single monoperiodic lattice and that in a bipartite one.Fil: Capuzzi, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Vignolo, P.. Université Côte D'azur; Franci
Momentum distribution of electrons in parabolic quantum dots
Full text linkWe investigate the momentum distribution of interacting electrons confined in a two-dimensional parabolic quantum dot for varying values of the interaction strength and for different number of electrons. We use an optimized Jastrow-type wave function for the ground state in which the Slater determinant part has been calculated using density-functional theory and evaluate the ground-state momentum distribution using the Fermi hypernetted-chain equations. We discuss the effects of interactions on the momentum distribution and reveal the existence of a shell structure in momentum space in analogy with what happens to the spatial density profile. The momentum distribution can thus be used as a further tool to investigate the effects of the interaction in parabolic quantum dots. © 2006 The American Physical Society.Fil: Gattobigio, M.. Institut de Physique de Nice; ItaliaFil: Capuzzi, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentin
Localization of an inhomogeneous Bose-Einstein condensate in a moving random potential
Full text linkWe study the dynamics of a harmonically trapped quasi-one-dimensional Bose-Einstein condensate subjected to a moving disorder potential of finite extent. We show that, due to the inhomogeneity of the sample, only a percentage of the atoms is localized at supersonic velocities of a random potential. We find that this percentage can be sensitively increased by introducing suitable correlations in the disorder potential such as those provided by random dimers. © 2012 American Physical Society.Fil: Alamir, Ardavan. Universite Nice; FranciaFil: Capuzzi, Pablo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Vignolo, Patrizia. Universite Nice; Franci
Confined quantum gases in multiple magnetic traps
Full text linkA partir del descubrimiento de la condensación de Bose-Einstein en gases diluidosconfinados, a mediados de 1995, una nueva rama de la física comenzó a desarrollarsefuertemente. Dentro de esta área, esta tesis abarca el estudio de las propiedadesen equilibrio y de las excitaciones de un gas de átomos confinados y enfriados atemperaturas donde la degeneración cuántica juega un papel fundamental. Motivadospor los hallazgos experimentales, se estudiaron sistemas con múltiplescomponentes bosónicas y fermiónicas. El análisis se enfocó en tres sistemas particulares:bosones en pozos dobles, fermiones puros, y mezclas fermiones-bosones. Dentro de estos temas exploramos, entre otras cosas, la dependencia de las funcionestermodinámicas con la geometría de pozo doble, la influencia de la interacciónen la temperatura crítica y en las excitaciones, la respuesta lineal de mezclas fermiónicaspuras y mezclas bosón-fermión ante perturbaciones multipolares. Entodos los casos la formulación de campo medio escogida dio resultados confiablese interesantes a la vez.Since the discovery of the Bose-Einstein condensation in dilute trapped gases in 1995, a new area in atomic physics began to develop strongly. Within this field,this PhD thesis embraces the study of the stationary properties and excitationsof a confined gas which has been cooled down to a temperature where quantumdegeneracy sets in. Encouraged by the latest experimental breakthroughs, westudied systems with multiple bosonic and fermionic components. The analysiswas focused on three especific systems: bosons in double-well traps, pure confinedfermions, and Bose-Fermi mixtures. We explored, within other topics, the dependenceof the thermodynamical functions upon the trap geometry, the influenceof interparticle interaction on both the critical temperature and the excitations,and the linear response of the gas mixtures against multipolar deformations of thetrap. We found that the mean-field formulation yields both reliable and interestingresults.Fil: Capuzzi, Pablo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
Comment on “Sound velocity and multibranch Bogoliubov spectrum of an elongated Fermi superfluid in the BEC-BCS crossover”
Full text linkFil: Capuzzi, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Vignolo, P.. No especifica;Fil: Federici, F.. No especifica;Fil: Tosi, M. P.. No especifica
Stationary arrays of vortices in Bose-Einstein condensates confined by a toroidal trap
Full text linkWe numerically study metastable arrays of vortices in three-dimensional Bose-Einstein condensates by solving the Gross-Pitaevskii equation with initial imprinted vorticity. We consider condensates confined by a harmonic plus Gaussian potential such as that used in a recent experiment. We analyse the energy barrier that prevents the vortices from leaving the trap and the spatial distribution of vortices for different trap parameters and winding numbers. For configurations forming rings of vortices we interpret the results in terms of the velocity fields produced by the vortices themselves and the spatial inhomogeneity of the condensate. For low enough densities, we found stationary configurations of multiply quantized vortices. © 2009 IOP Publishing Ltd.Fil: Capuzzi, Pablo. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Jezek, Dora Marta. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentin
Enhancing quantum coherence with short-range correlated disorder
Full text linkWe introduce a two-dimensional short-range correlated disorder that is the natural generalization of the well-known one-dimensional dual random dimer model [D. H. Dunlap et al., Phys. Rev. Lett. 65, 88 (1990)]. We demonstrate that, as in one dimension, this model induces a localization-delocalization transition in the single-particle spectrum. Moreover we show that the effect of such a disorder on a weakly interacting boson gas is to enhance the condensate spatial homogeneity and delocalization and to increase the condensate fraction around an effective resonance of the two-dimensional dual dimers. This study proves that short-range correlations of a disordered potential can enhance the quantum coherence of a weakly interacting many-body system.Fil: Capuzzi, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; ArgentinaFil: Gattobigio, M.. Institut Non Linéaire de Nice; FranciaFil: Vignolo, P.. Institut Non Linéaire de Nice; Franci
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