Fermionic bright soliton in a boson-fermion mixture

TL;DR

This paper demonstrates the formation of stable fermionic bright solitons in a boson-fermion mixture with attractive interactions using a dynamical mean-field-hydrodynamic model, including effects of optical lattices.

Contribution

It introduces a model showing how attractive boson-fermion interactions enable fermionic bright solitons, which were previously thought impossible with repulsive interactions.

Findings

Stable fermionic bright solitons form with attractive interactions.

Optical lattice potentials support fermionic soliton formation.

Solitons are experimentally realizable with current technology.

Abstract

We use a time-dependent dynamical mean-field-hydrodynamic model to study the formation of fermionic bright solitons in a trapped degenerate Fermi gas mixed with a Bose-Einstein condensate in a quasi-one-dimensional cigar-shaped geometry. Due to a strong Pauli-blocking repulsion among spin-polarized fermions at short distances there cannot be bright fermionic solitons in the case of repulsive boson-fermion interactions. However, we demonstrate that stable bright fermionic solitons can be formed for a sufficiently attractive boson-fermion interaction in a boson-fermion mixture. We also consider the formation of fermionic solitons in the presence of a periodic axial optical-lattice potential. These solitons can be formed and studied in the laboratory with present technology.