Expansion of spherical shell condensates

Bose-condensed atoms in traps of novel geometries can show dramatic features in time-of-flight measurements that are absent in conventional spherical trap settings. The specific case of a trap creating a spherical condensate shell is presented. The dynamics of such a shell can yield a significant accumulation of mass at the center upon release of the trapping potential. Morever, the expanded cloud can undergo self- interference and exhibit the associated interference fringes. These features are substantiated by numerical simulations and studied for a range of interaction strength between constituent atoms.