JOSEPHSON DYNAMICS IN TOROIDALLY CONFINED DIPOLAR CONDENSATES

M. ABAD; M. GUILLEUMAS; R. MAYOL; M. PI; D. M. JEZEK

Foz do Iguazu,

Workshop; The nineteenth annual International Laser Physics Workshop (LPHYS'10); 2010

Due to the large magnetic dipole moment of chromium atoms, a condensate of 52Cr is a very suitable system for studying the effects of dipolar interactions. In contrast to the usual s-wave contact interaction, dipole-dipole interactions are anisotropic and long range and these properties introduce new physics in the  field of Bose-Einstein condensation. In particular, their anisotropic character can be enhanced in specific configurations, leading to a rich variety of phenomena. We are interested in the dynamics arising from dipolar interactions in a multiply connected geometry. For this purpose a system of 52Cr atoms is considered to be confined in a toroidal potential with the trap symmetry axis along z, and with the dipoles aligned along the y-axis. For small scattering lengths the density presents two symmetric peaks in the perpendicular axis (x), while along y the density becomes smaller [1]. This behavior can be understood in terms of a self-induced energy barrier that the mean-field dipolar interaction creates in the condensate, defining therefore two symmetric wells connected by two links. In such a configuration and for an initial asymmetry between the left and right wells (given by population imbalance and phase difference) the system shows a Josephson-like dynamics which can be qualitatively described by a two-mode model. In addition a regime can be predicted where quantum self-trapping occurs. In this work we study Josephson dynamics of a dipolar condensate confined in a toroidal trap by solving the Gross-Pitaevskii equation in real-time and compare these results with a two-mode analysis.References[1] M. Abad, M. Guilleumas, R. Mayol, M. Pi, and D. M. Jezek, arXiv: 1001.3594 (2010).