Gap and embedded solitons in microwave-coupled binary condensates

TL;DR

This paper explores the existence and stability of gap and embedded solitons in microwave-coupled binary Bose-Einstein condensates influenced by spin-orbit coupling and Zeeman splitting, revealing new stable soliton families and collision behaviors.

Contribution

It introduces a novel setting for binary BECs with microwave coupling, demonstrating the formation of stable gap and embedded solitons influenced by microwave-mediated interactions.

Findings

Families of stable gap and embedded solitons are found.

Solitons exhibit skew symmetry and include fundamental and dipole types.

Moving solitons have a specific stability region and merge upon collision.

Abstract

It was recently found that, under the action of the spin-orbit coupling (SOC) and Zeeman splitting (ZS), binary BEC with intrinsic cubic nonlinearity supports families of gap solitons, provided that the kinetic energy is negligible in comparison with the SOC and ZS terms. We demonstrate that, also under the action of SOC and ZS, a similar setting may be introduced for BEC with two components representing different atomic states, resonantly coupled by microwave radiation, while the Poisson equation accounts for the feedback of the two-component atomic wave function onto the radiation. The microwave-mediated interaction induces an effective nonlinear trapping potential, which strongly affects the purport of the linear spectrum in this system. As a result, families of both gap and embedded solitons (those overlapping with the continuous spectrum) are found, being chiefly stable. The shape of the solitons features exact or broken skew symmetry. In addition to fundamental solitons (whose shape may or may not include a node), a family of dipole solitons is constructed too, which are even more stable than their fundamental counterparts. A nontrivial stability area is identified for moving solitons in the present system, which lacks Galilean invariance. Colliding solitons merge into a single one.