Splitting a Bose-Einstein condensate in two translating traps

Motivated by an earlier proposal of splitting a one-dimensional atomic wave packet using two translating traps [Zhang , Phys. Rev. Lett. 97, 070403 (2006)], we report results of simulating the splitting dynamics for a three-dimensional Bose-Einstein condensate at zero temperature. Different from the single-atom case where the population in one of the traps shows full oscillations as a function of the translating velocity, we find that such oscillations are damped as the translating velocity decreases. As the interaction increases, we see a stronger damping effect. The damping mechanism is attributed to the formation of solitons which decay to vortex rings and cause complicated flow patterns to damp the population oscillations. Our conclusions are supported by results for N=5400 and N=54 000 Rb-87 atoms. In the adiabatically translating regime, the condensate can only be split 50:50. Therefore, a controlled splitting of the condensate in two symmetric traps can only be realized for a small number of atoms and away from the adiabatic regime.