FREE EXPANSION OF BOSE-EINSTEIN CONDENSATES WITH INITIALLY APPLIED VELOCITY FIELDS

P. CAPUZZI; D. M. JEZEK

Foz do Iguazu

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

We investigate the evolution of the aspect ratio of freely expanding Bose-Einstein condensates initially carrying non-trivial velocity fields and after being confined by anisotropic potentials. The analysis of the dynamics of the expansion permits us to characterize the initial state of the system. By developing a simple numerical strategy we are able to study large expansion rates of the condensate governed by the Gross-Pitaevskii equation. We illustrate its application in two specific cases: a condensate obtained by applying an off-axis spherical quadrupole oscillation for a period of time [1], and a condensate with an initial array of pinned vortices. We find that the final aspect ratio of the condensate may noticeably deviate from the prediction of the scaling Thomas-Fermi theory [2] and become closer to unity depending on the magnitude of the interaction energy and the anisotropy of the velocity field.[1] E. A. L. Henn, J. A. Seman, G. Roati, K. M. F. Magalh˜aes, and V. S. Bagnato, Phys.Rev. Lett. 103, 045301 (2009).[2] Y. Castin and R. Dum, Phys. Rev. Lett. 77, 5315 (1996).