Watching dark solitons decay into vortex rings in a Bose-Einstein condensate

We have created spatial dark solitons in two-component Bose-Einstein conden sates in which the soli ton exists in one of the condensate components and the soliton nodal plane is filled with the second component. The filled sol itons are stable for hundreds of milliseconds. The filling can be selective ly removed, making the soliton more susceptible to dynamical instabilities. For a condensate in a spherically symmetric potential, these instabilities cause the dark soliton to decay into stable vortex rings. We have imaged t he resulting vortex rings.