Bulletin of the American Physical Society
Dark-bright soliton interactions beyond the integrable limit
Panos Kevrekidis, G. C. Katsimiga, Jan Stockhofe, Peter Schmelcher
Abstract
In this work we present a systematic theoretical analysis regarding dark-bright solitons and their interactions,motivated by recent advances in atomic two-component repulsively interacting Bose-Einstein condensates. Inparticular, we study analytically via a two-soliton ansatz adopted within a variational formulation the interactionbetween two dark-bright solitons in a homogeneous environment beyond the integrable regime, by consideringgeneral inter/intra-atomic interaction coefficients. We retrieve the possibility of a fixed point in the case wherethe bright solitons are out of phase. As the inter-component interaction is increased, we also identify an exponentialinstability of the two-soliton state, associated with a subcritical pitchfork bifurcation. The latter givesrise to an asymmetric partition of the bright soliton mass and dynamically leads to spontaneous splitting of thebound pair. In the case of the in-phase bright solitons, we explain via parsing the analytical approximations andmonitoring the direct dynamics why no such pair is identified, despite its prediction by the variational analysis.