  We investigate numerically the collisions of two distinguishable quantum
matter-wave bright solitons in a one-dimensional harmonic trap. We show that
such collisions can be used to generate mesoscopic Bell states which can
reliably be distinguished from statistical mixtures. Calculation of the
relevant s-wave scattering lengths predicts that such states could potentially
be realized in quantum-degenerate mixtures of 85Rb and 133Cs. In addition to
fully quantum simulations for two distinguishable two-particle solitons, we use
a mean-field description supplemented by a stochastic treatment of quantum
fluctuations in the soliton's center of mass: We demonstrate the validity of
this approach by comparison to a mathematically rigorous effective potential
treatment of the quantum many-particle problem.
