Diasporic consciousness in contemporary Colombia

published or submitted for publicationis peer reviewe

García Márquez y los últimos bolívares de la Gran Colombia

El general en su laberinto. Gabriel García Márquez. Editorial Oveja Negra, Bogotá, 1989, 286 págs

Hacia una poética: el premio Nobel y sus circunstancias

El primer borrador de este trabajo fue un discurso pronunciado en abril del 2000, en el Primer Foro Internacional sobre Gabriel García Márquez en el XXXIII Festival de la Leyenda Vallenata, en Valledupar, Colombia. Gracias al Ministerio de Cultura de Colombia (y su ministro, Juan Luis Mejía) y a la Fundación Festival de la Leyenda Vallenata (y su presidenta, Consuelo Araujo-Noguera), por la invitación y el apoyo

La primera novela de García Márquez después del premio Nóbel

En los primeros días de diciembre de 1985, en Colombia, se parrandeaba, y no a causa de las ferias o la navidad. Se pronunciaban discursos. Aparecían anuncios en los periódicos, en las revistas, en la televisión. ¿Objeto de toda la atención? Gabriel García Márquez y su nueva novela, El amor en los tiempos del cólera. Esta, comenzada en agosto de 1982, antes del obsequio del premio que forzó a García Márquez a tomarse un año sabático para administrar la fama , estaba a punto de publicarse

Dipole Oscillations of a Fermi Gas in a Disordered Trap: Damping and Localization

We theoretically study the dipole oscillations of an ideal Fermi gas in a disordered trap. We show that even weak disorder induces strong damping of the oscillations and we identify a metal-insulator crossover. For very weak disorder, we show that damping results from a dephasing effect related to weak random perturbations of the energy spectrum. For increasing disorder, we show that the Fermi gas crosses over to an insulating regime characterized by strong-damping due to the proliferation of localized states.Comment: published as EPL 88 (2009) 3000

Three-dimensional localization of ultracold atoms in an optical disordered potential

We report a study of three-dimensional (3D) localization of ultracold atoms suspended against gravity, and released in a 3D optical disordered potential with short correlation lengths in all directions. We observe density profiles composed of a steady localized part and a diffusive part. Our observations are compatible with the self-consistent theory of Anderson localization, taking into account the specific features of the experiment, and in particular the broad energy distribution of the atoms placed in the disordered potential. The localization we observe cannot be interpreted as trapping of particles with energy below the classical percolation threshold.Comment: published in Nature Physics; The present version is the initial manuscript (unchanged compared to version 1); The published version is available online at http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys2256.htm

Experimental study of the transport of coherent interacting matter-waves in a 1D random potential induced by laser speckle

We present a detailed analysis of the 1D expansion of a coherent interacting matterwave (a Bose-Einstein condensate) in the presence of disorder. A 1D random potential is created via laser speckle patterns. It is carefully calibrated and the self-averaging properties of our experimental system are discussed. We observe the suppression of the transport of the BEC in the random potential. We discuss the scenario of disorder-induced trapping taking into account the radial extension in our experimental 3D BEC and we compare our experimental results with the theoretical predictions

Transport regimes of cold gases in a two-dimensional anisotropic disorder

We numerically study the dynamics of cold atoms in a two-dimensional disordered potential. We consider an anisotropic speckle potential and focus on the classical regime, which is relevant to some recent experiments. First, we study the behavior of particles with a fixed energy and identify different transport regimes. For low energy, the particles are classically localized due to the absence of a percolating cluster. For high energy, the particles undergo normal diffusion and we show that the diffusion constants scale algebraically with the particle energy, with an anisotropy factor which significantly differs from that of the disordered potential. For intermediate energy, we find a transient sub-diffusive regime, which is relevant to the time scale of typical experiments. Second, we study the behavior of a cold-atomic gas with an arbitrary energy distribution, using the above results as a groundwork. We show that the density profile of the atomic cloud in the diffusion regime is strongly peaked and, in particular, that it is not Gaussian. Its behavior at large distances allows us to extract the energy-dependent diffusion constants from experimental density distributions. For a thermal cloud released into the disordered potential, we show that our numerical predictions are in agreement with experimental findings. Not only does this work give insights to recent experimental results, but it may also serve interpretation of future experiments searching for deviation from classical diffusion and traces of Anderson localization.Comment: 19 pages, 16 figure