  By cyclic adiabatic change of two control parameters of an optical trap one
can induce a circulating current of condensed bosons. The amount of particles
that are transported per period depends on the "radius" of the cycle, and this
dependence can be utilized in order to probe the interatomic interactions. For
strong repulsive interaction the current can be regarded as arising from a
sequence of Landau-Zener crossings. For weaker interaction one observes either
gradual or coherent mega crossings, while for attractive interaction the
particles are glued together and behave like a classical ball. For the analysis
we use the Kubo approach to quantum pumping with the associated Dirac monopoles
picture of parameter space.
