Momentum interferences of a freely expanding Bose-Einstein condensate due to interatomic interaction change

A Bose-Einstein condensate may be prepared in a harmonic trap with negligible interatomic interactions using a Feshbach resonance. If a strong repulsive interatomic interaction is switched on and the trap is removed to let the condensate evolve freely, a time dependent quantum interference pattern takes place in the short time (Thomas-Fermi) regime, in which the number of peaks of the momentum distribution increases one by one, whereas the spatial density barely changes. The effect is stable for initial states with interactions and realistic time-dependence of the scattering length.