Nonlinear Supression of Tunneling and Strong Localization in   Bose-Einstein Condensates with Spatially Inhomogeneous Interactions
  We study the properties of the ground state of Bose-Einstein condensates with spatially inhomogeneous interactions and show that the atom density experiences a strong localization at the spatial region where the scattering length is close to zero while tunneling to regions with positive values of the scattering length is strongly supressed by the nonlinear interactions. 
Victor M. Perez-Garcia