Transmission of matter wave solitons through nonlinear traps and barriers

The transmissions of matter wave solitons through linear and nonlinear inhomogeneities induced by the spatial variations of the trap and the scattering length in Bose-Einstein condensates are investigated. New phenomena, such as the enhanced transmission of a soliton through a linear trap by a modulation of the scattering length, are exhibited. The theory is based on the perturbed Inverse Scattering Transform for solitons, and we show that radiation effects are important. Numerical simulations of the Gross-Pitaevskii equation confirm the theoretical predictions.