Bright solitons and soliton trains in a fermion-fermion mixture

TL;DR

This paper predicts and analyzes the formation of bright fermionic solitons and soliton trains in a degenerate fermion-fermion mixture using a dynamical mean-field model, highlighting conditions for their stability and experimental realization.

Contribution

It introduces a dynamical mean-field-hydrodynamic model to study bright solitons in fermion mixtures, revealing stable formations under attractive interspecies interactions.

Findings

Bright solitons form with attractive interspecies interactions.

Stable soliton trains can be generated and studied.

Repulsive interactions do not support bright solitons.

Abstract

We use a time-dependent dynamical mean-field-hydrodynamic model to predict and study bright solitons in a degenerate fermion-fermion mixture in a quasi-one-dimensional cigar-shaped geometry using variational and numerical methods. Due to a strong Pauli-blocking repulsion among identical spin-polarized fermions at short distances there cannot be bright solitons for repulsive interspecies fermion-fermion interactions. However, stable bright solitons can be formed for a sufficiently attractive interspecies interaction. We perform a numerical stability analysis of these solitons and also demonstrate the formation of soliton trains. These fermionic solitons can be formed and studied in laboratory with present technology.