Unlike weakly interacting BEC, solitons in hard core bosonic gases support both dark and bright solitons .solitary waves.These solitons survive collision and quantum fluctuations.
“Quantum Dynamics of Solitons in Strongly Interacting Systems on Optical Lattices”, Chester P. Rubbo, Indubala I. Satija, William P. Reinhardt, Radha Balakrishnan,Ana Maria Rey,1 and Salvatore R. Manmana , Phys. Rev. A 85, 053617 (2012) …