Proper phase imprinting method for a dark soliton excitation in a superfluid Fermi mixture

TL;DR

This paper demonstrates that in superfluid Fermi mixtures, effective dark soliton excitation requires phase imprinting only on one component, unlike the standard method applied to both components.

Contribution

It introduces a modified phase imprinting technique tailored for superfluid Fermi mixtures to successfully generate dark solitons.

Findings

Standard phase imprinting on both components fails in Fermi superfluids.

Single-component phase imprinting produces the desired dark soliton.

The method aligns with the symmetry properties of the Bogoliubov-de Gennes equations.

Abstract

It is common knowledge that a dark soliton can be excited in an ultra-cold atomic gas by means of the phase imprinting method. We show that, for a superfluid fermionic mixture, the standard phase imprinting procedure applied to both components fails to create a state with symmetry properties identical to those of the dark soliton solution of the Bogoliubov-de Gennes equations. To produce a dark soliton in the BCS regime, a single component of the Fermi mixture should be phase imprinted only.