Soliton molecules in trapped vector nonlinear Schrödinger systems.

We propose a method to build a great variety of stable multisoliton "molecules" with coupled light beams in Kerr graded index (GRIN) media or atomic mixtures of Bose-Einstein condensates. We present a general theory and discuss several specific cases, including two-, three-, and four-atom molecules made up of Gaussian modes or vortices. A three-dimensional example is also presented.