Two-dimensional symbiotic solitons and vortices in binary condensates with attractive cross-species interaction

TL;DR

This paper investigates the existence and stability of two-dimensional symbiotic solitons and vortices in a binary condensate system with attractive cross-species interactions, using numerical and analytical methods, including a variational approximation.

Contribution

It introduces new stable 2D symbiotic solitons and vortices in a spinor system with attractive inter-component interactions, stabilized by a periodic potential, and provides detailed stability analysis.

Findings

Stable symmetric and asymmetric fundamental solitons and vortices identified.

Variational approximation accurately predicts soliton and vortex properties.

Stability regions depend on the strength of inter-component attraction versus intra-species repulsion.

Abstract

We consider a two-dimensional (2D) two-component spinor system with cubic attraction between the components and intra-species self-repulsion, which may be realized in atomic Bose-Einstein condensates, as well as in a quasi-equilibrium condensate of microcavity polaritons. Including a 2D spatially periodic potential, which is necessary for the stabilization of the system against the critical collapse, we use detailed numerical calculations and an analytical variational approximation (VA) to predict the existence and stability of several types of 2D symbiotic solitons in the spinor system. Stability ranges are found for symmetric and asymmetric symbiotic fundamental solitons and vortices, including hidden-vorticity (HV) modes, with opposite vorticities in the two components. The VA produces exceptionally accurate predictions for the fundamental solitons and vortices. The fundamental solitons, both symmetric and asymmetric ones, are completely stable, in either case when they exist as gap solitons or regular ones. The symmetric and asymmetric vortices are stable if the inter-component attraction is stronger than the intra-species repulsion, while the HV modes have their stability region in the opposite case.