Symmetry breaking in dipolar matter-wave solitons in dual-core couplers

TL;DR

This paper investigates spontaneous symmetry-breaking in dipolar Bose-Einstein condensate solitons within dual-core systems, revealing stability regions, collision behaviors, and PT-symmetric properties, advancing understanding of nonlinear matter-wave dynamics.

Contribution

It introduces and analyzes dual-core models with dipole-dipole interactions, identifying symmetry-breaking types, stability conditions, and collision outcomes, including PT-symmetric configurations.

Findings

Symmetry-breaking occurs in supercritical and subcritical forms.

Stable asymmetric and symmetric solitons are identified.

Collision dynamics include elastic rebound, merger, and vibrations.

Abstract

We study effects of the spontaneous symmetry-breaking (SSB) in solitons built of the dipolar Bose-Einstein condensate (BEC), trapped in a dual-core system with the dipole-dipole interactions (DDIs) and hopping between the cores. Two realizations of such a matter-wave coupler are introduced, weakly- and strongly-coupled. The former one in based on two parallel pipe-shaped traps, while the latter one is represented by a single pipe sliced by an external field into parallel layers. The dipoles are oriented along axes of the pipes. In these systems, the dual-core solitons feature the SSB of the supercritical type and subcritical types, respectively. Stability regions are identified for symmetric and asymmetric solitons, and, in addition, for non-bifurcating antisymmetric ones, as well as for symmetric flat states, which may also be stable in the strongly-coupled system, due to competition between the attractive and repulsive intra- and inter-core DDIs. Effects of the contact interactions are considered too. Collisions between moving asymmetric solitons in the weakly-symmetric system feature elastic rebound, merger into a single breather, and passage accompanied by excitation of intrinsic vibrations of the solitons, for small, intermediate, and large collision velocities, respectively. A PT-symmetric version of the weakly-coupled system is briefly considered too, which may be relevant for matter-wave lasers. Stability boundaries for PT-symmetric and antisymmetric solitons are identified.