Bright solitons in coupled defocusing NLS equation supported by coupling: Application to Bose-Einstein condensation

TL;DR

This paper explores how attractive interspecies coupling in coupled defocusing NLS equations can support bright solitons, with applications to creating stable bright solitons in two-component Bose-Einstein condensates.

Contribution

It demonstrates the formation of bright solitons supported by attractive coupling in defocusing NLS equations and applies this to stable soliton formation in two-component BECs.

Findings

Bright solitons form in coupled defocusing NLS with attractive coupling.

Interspecies attraction induces effective attraction among same species.

Stable bright solitons can exist in repulsive BECs with sufficient interspecies attraction.

Abstract

We demonstrate the formation of bright solitons in coupled defocusing nonlinear Schroedinger (NLS) equation supported by attractive coupling. As an application we use a time-dependent dynamical mean-field model to study the formation of stable bright solitons in two-component repulsive Bose-Einstein condensates (BECs) supported by interspecies attraction in a quasi one-dimensional geometry. When all interactions are repulsive, there cannot be bright solitons. However, bright solitons can be formed in two-component repulsive BECs for a sufficiently attractive interspecies interaction, which induces an attractive effective interaction among bosons of same type.