Dear Sudharsan, The measure of chemical potential can identify Gap-Soliton as chemical potential corresponding to Gap-Soliton in the presence of optical lattice (OL) lie in the gap of the band spectrum of the linear Bloch-wave spectrum (energy spectrum of OL ). Another indicator can be the non-dispersive behaviour in the time evolution of matter-wave.

Dear Muhammad Ayub,

Thanks for your answer regarding gap soliton. Are working with solitons in BEC?

Partially Yes. My attention are about the coherent dynamics of matter waves in driven optical lattices.