  We show that the presence of soliton in a single-species condensate, at zero
temperature, enhances the quantum depletion sufficient enough to induce
dynamical instability of the system. We also predict that for two-species
condensates, two Goldstone modes emerge in the excitation spectrum at phase
separation. Of these, one is due to the presence of the soliton. We use
Hartree-Fock-Bogoliubov theory with Popov approximation to examine the mode
evolution, and demonstrate that when the anomalous mode collides with a higher
energy mode it renders the solitonic state oscillatory unstable. We also report
soliton induced change in the topology of the density profiles of the
two-species condensates at phase-separation.
