  Recent experiments with Feshbach-resonant cesium Bose-Einstein condensates
have led to unexplained molecule formation: a sudden switch of the magnetic
field to its resonance value, followed by a finite hold time and another sudden
switch to magnetic field values below threshold, converts about a third of the
initial condensate atoms into molecules. Based on a model of coherent
conversion between an atomic condensate, a molecular condensate, and
magnetodissociated noncondensate atom pairs of equal and opposite momentum, we
find that population trapping is strongly implicated as the physical mechanism
responsible for molecule formation in switch experiments.
