Quasi-one- and quasi-two-dimensional Bose-Fermi mixtures from weak coupling to unitarity

We study ultracold superfluid Bose-Fermi mixtures in three dimensions, with stronger confinement along one or two directions, using a non-perturbative beyond-mean-field model for bulk chemical potential valid along the weak-coupling to unitarity crossover. Although bosons are considered to be in a superfluid state, we consider two possibilities for the fermions - spin-polarized degenerate state and superfluid state. Simplified reduced analytic lower-dimensional models are derived along the weak-coupling to unitarity crossover in quasi-one-dimensional (quasi-1D) and quasi-two-dimensional (quasi-2D) settings. The only parameters in these models are the constants of the beyond-mean-field Bose-Bose and Fermi-Fermi Lee-Huang-Yang interactions and the respective universal Bertsch parameter at unitarity. In addition to the numerical results for a fully-trapped system, we also present results for quasi-2D Bose-Fermi mixtures where one of the components is untrapped but localized due to the interaction mediated by the other component. We demonstrate the validity of the reduced quasi-1D and quasi-2D models via a comparison of the numerical solutions for the ground states obtained from the reduced models and the full three-dimensional (3D) model.

Automated summary

In this study, ultracold superfluid Bose-Fermi mixtures in three dimensions with stronger confinement along one or two directions are investigated using a non-perturbative beyond-mean-field model. Two possibilities for the fermions are considered - a spin-polarized degenerate state and a superfluid state. Simplified lower-dimensional models are derived for the weak-coupling to unitarity crossover in quasi-one-dimensional and quasi-two-dimensional settings. The validity of these reduced models is demonstrated through a comparison with the numerical solutions from the full three-dimensional model.