A two-photon transition is used to convert an arbitrary fraction of the atoms in a condensate to the state. Transferring the entire population imposes a discontinuous change on the condensate's mean-field repulsion, which leaves a residual ringing in the condensate width. A calculation based on Gross-Pitaevskii theory agrees well with the observed behavior, and from the comparison we obtain the ratio of the intraspecies scattering lengths for the two states, .
- Received 11 March 1998
©1998 American Physical Society