Spin Hall Effect of Excitons

Spin Hall effect for excitons in alkali halides and in Cu_2O is investigated theoretically. In both systems, the spin Hall effect results from the Berry curvature in k space, which becomes nonzero due to lifting of degeneracies of the exciton states by exchange coupling. The trajectory of the excitons can be directly seen as spatial dependence of the circularly polarized light emitted from the excitons. It enables us to observe the spin Hall effect directly in the real-space time.Comment: 5 pages, 2 figure

Holographic storage of multiple coherence gratings in a Bose-Einstein condensate

We demonstrate superradiant conversion between a two-mode collective atomic state and a single-mode light field in an elongated cloud of Bose-condensed atoms. Two off-resonant write beams induce superradiant Raman scattering, producing two independent coherence gratings with a different wave vector in the cloud. By applying phase-matched read beams after a controllable delay, the gratings can be selectively converted into the light field also in a superradiant way. Due to the large cooperativity parameter and the small velocity width of the condensate, a high conversion efficiency of $> 70$ % and a long storage time of $> 120$ $\mu$s were achieved.Comment: 5 pages, 4 figure

Hodge structures associated to SU(p,1)

Let A be an abelian variety over C such that the semisimple part of the Hodge group of A is a product of copies of SU(p,1) for some p>1. We show that any effective Tate twist of a Hodge structure occurring in the cohomology of A is isomorphic to a Hodge structure in the cohomology of some abelian variety

Guía para facilitadores y facilitadoras de talleres de GEM

89 p. Libro electrónicoEl Programa de Apoyo a las Redes de Mujeres (PARM) de APC es tanto un programa de la asociación, como una red de mujeres de todo el mundo que tienen un compromiso con el uso de la tecnología para el empoderamiento y la igualdad de ellas. Fundada en 1993, nuestra red cuenta hoy con más de 175 mujeres de 35 países—bibliotecarias, programadoras, periodistas, capacitadoras, diseñadoras, académicas, investigadoras y comunicadoras. La Metodología de Evaluación de Género (GEM) se desarrolló en APC dentro del programa de mujeres cuando empezamos a investigar el impacto de nuestro trabajo en 2000. Nos preguntamos: ¿Qué cambios empoderan a las mujeres? ¿Cómo se miden esos cambios? ¿Qué papel tienen las TIC en ellos? ¿Cómo inciden en las relaciones de género entre hombres y mujeres? En aquel momento no existían modelos de herramientas de evaluación de género que analizaran específicamente el uso de las TIC o de la tecnología. En 2001, empezamos a desarrollar GEM con practicantes de TIC para el desarrollo en 25 países de América Latina, Asia, África y Europa Central y Oriental. El manual de GEM se desarrolló inicialmente para internet y las TIC, pero la experiencia muestra que GEM también se puede usar para mejorar las relaciones de género en el sector del desarrollo en general

Chaotic dynamics of cold atoms in far-off-resonant donut beam

We describe the classical two dimensinal nonlinear dynamics of cold atoms in far-off-resonant donut beams. We show that there chaotic dynamics exists for charge greater than unity, when the intensity of the beam is periodically modulated. The two dimensional distributions of atoms in $(x,y)$ plane for charge two are simulated. We show that the atoms will acumulate on several ring regions when the system enters to regime of global chaos.Comment: 8 pages, 8 figure

Strong valence fluctuation in the quantum critical heavy fermion superconductor beta-YbAlB4: A hard x-ray photoemission study

Electronic structures of the quantum critical superconductor beta-YbAlB4 and its polymorph alpha-YbAlB4 are investigated by using bulk-sensitive hard x-ray photoemission spectroscopy. From the Yb 3d core level spectra, the values of the Yb valence are estimated to be ~2.73 and ~2.75 for alpha- and beta-YbAlB4, respectively, thus providing clear evidence for valence fluctuations. The valence band spectra of these compounds also show Yb2+ peaks at the Fermi level. These observations establish an unambiguous case of a strong mixed valence at quantum criticality for the first time among heavy fermion systems, calling for a novel scheme for a quantum critical model beyond the conventional Doniach picture in beta-YbAlB4.Comment: 4 pages, 3 figures, revised version accepted for publication in PR

Evaluation of Gender for Agriculture and Rural Development in the Information Society (GenARDIS) - phases I and II : summary of key findings and recommendations (evaluation period: July-November 2006)

Evaluation team members: Angela M. Kuga Thas, Sylvie Niombo, Natasha Lee Primo, Jennifer Radloff, Lenka Simersk