Dynamically Slowed Collapse of a Bose-Einstein Condensate with Negative   Scattering Length
  We rapidly change the scattering length a_s of a 87Rb Bose-Einstein condensate by means of a Feshbach resonance, simultaneously releasing the condensate from its harmonic trapping potential. When a_s is changed from positive to negative, the subsequent collapse of the condensate is stabilized by the kinetic energy imparted during the release, resulting in a deceleration of the loss rate near the resonance. We also observe an increase in the Thomas-Fermi radius, near the resonance, that cannot be understood in terms of a simple scaling model. Instead, we describe this behavior using the Gross-Pitaevskii equation, including three-body recombination, and hypothesize that the increase in cloud radius is due to the formation of concentric shells. 
R. L. Compton, Y.-J. Lin, K. Jimenez-Garcia, J. V. Porto, and I. B.   Spielman
cond-mat.quant-gas physics.atom-ph