Solitons of Bose-Fermi mixtures in a strongly elongated trap

TL;DR

This paper investigates soliton solutions in a strongly elongated Bose-Fermi mixture, showing how trap geometry and Feshbach resonance can control interactions and stability of these localized wave structures.

Contribution

It derives a coupled one-dimensional model for Bose-Fermi mixtures in anisotropic traps and analyzes conditions for soliton formation and modulational instability.

Findings

Solitons can be formed with density variations in both components.

Interaction types are tunable via trap geometry and Feshbach resonance.

The system exhibits modulational instability depending on interaction parameters.

Abstract

It is shown that a Bose-Fermi mixture of a degenerate gas of spin-polarized fermions, whose number significantly exceeds the number of bosons, embedded in a strongly anisotropic trap, is described by the one-dimensional coupled nonlinear Schrodinger equation for the boson component and the wave equation with external source for the fermion component. Depending on the type of boson-fermion interaction, the system may display modulational instability and the existence of solitons in the fermion and boson components respectively. Such solitons represent either a local decrease (increase) of the density of both the components or a decrease of the density in one component and an increase of the density in the other component. It is shown that the type of the effective interactions can be easily managed by varying the trap geometry or by means of Feshbach resonance.