Bose polaronic soliton-molecule and vector solitons in PT-symmetric potential

We study analytically and numerically the properties of polaronic soliton molecules and vector solitons of a trapped Bose Einstein condensate (BEC)-impurity mixture subjected to a PT-symmetric potential in a quasi one-dimensional geometry employing our time dependent Hartree-Fock-Bogoliubov equations. Analytical results, based on a variational approach and checked with direct numerical simulations reveal that the width, chirp, the vibration frequency and the profile of impurity solitons are enhanced by varying the strengths of real and imaginary parts of PT-symmetric potential as well as the boson-boson and boson-impurity interaction. We address the impact of the imaginary part of the potential, which represents a gain-loss mechanism, on the dynamics and on the stability of the impurity soliton-molecule. We show that for sufficiently strong complex part of the potential, the single soliton exhibits a snake instability and the molecule destroys analogous to the dissociation of a diatomic molecule. We discuss, on the other hand, the formation of several unusual families of three-component vector solitons in the BEC-impurity mixture. An unconventional dark (D)-bright (B) soliton conversion is found. (C) 2017 Elsevier B.V. All rights reserved.