Gaussian-like and flat-top solitons of atoms with spatially modulated repulsive interactions

TL;DR

This paper introduces a model for ultracold atoms with spatially modulated repulsive interactions that supports stable flat-top matter-wave solitons, expanding understanding of soliton types in nonlinear media.

Contribution

It proposes a new model supporting stable flat-top solitons in ultracold atoms with spatially modulated interactions, including 1D and 2D varieties, and analyzes their stability.

Findings

Stable flat-top solitons can be generated by varying physical parameters.

Transformation from Gaussian to flat-top solitons is demonstrated.

Stability domains are confirmed by linear analysis and simulations.

Abstract

Solitons, nonlinear particle-like excitations with inalterable properties (amplitude, shape, and velocity) as they propagate, are omnipresent in many branches of science---and in physics in particular. Flat-top solitons are a novel type of bright solitons that have not been well explored in pure nonlinear media. Here, a model of nonlinear Kerr (cubic) media of ultracold atoms with spatially modulated repulsive interactions is proposed and shown to support a vast variety of stable flat-top matter-wave solitons, including one-dimensional (1D) flat-top fundamental and multipole solitons, two-dimensional (2D) flat-top fundamental and vortex solitons. We demonstrate that by varying the relevant physical parameters (nonlinearity coefficient and chemical potential) the ordinary bright (gaussian) solitons can transform into the novel flat-top solitons. The (in-)stability domains of the flat-top soliton families are checked by means of linear stability analysis and reconfirmed by direct numerical simulations. This model is generic in the contexts of nonlinear optics and Bose-Einstein condensates, which provide direct experimental access to observe the predicted solutions.