Observation of dense collisional soliton complexes in a two-component Bose-Einstein condensate

We present an experimental and theoretical study of hydrodynamic phenomena in a two-component atomic Bose-Einstein condensate emerging from the imprinting of a periodic spin pattern. By employing a microwave pulse-based winding technique, we prepare a tunable initial state which evolves into an array of solitary waves. We observe the ensuing dynamics, including shape deformations, the emergence of dark-antidark solitons, apparent spatial frequency tripling, and decay and revival of contrast related to soliton collisions. For the densest arrays, we obtain soliton complexes where solitons undergo continued collisions for long evolution times providing an avenue towards the investigation of soliton gases in atomic condensates.