Quantum phases in mixtures of fermionic atoms

TL;DR

This paper investigates quantum phases in mixtures of fermionic atoms on a 2D optical lattice, revealing how interactions and temperature influence spectral gaps and atomic distributions.

Contribution

It models the system as a Falicov-Kimball type alloy, combining numerical methods to analyze spectral and distributional properties across interaction regimes.

Findings

Scattering by heavy atoms can open a spectral gap in light atoms.

Strong interactions or low temperatures induce insulating phases.

Numerical results show the transition between metallic and insulating states.

Abstract

A mixture of spin-polarized light and heavy fermionic atoms on a finite size 2D optical lattice is considered at various temperatures and values of the coupling between the two atomic species. In the case, where the heavy atoms are immobile in comparison to the light atoms, this system can be seen as a correlated binary alloy related to the Falicov-Kimball model. The heavy atoms represent a scattering environment for the light atoms. The distributions of the binary alloy are discussed in terms of strong- and weak-coupling expansions. We further present numerical results for the intermediate interaction regime and for the density of states of the light particles. The numerical approach is based on a combination of a Monte-Carlo simulation and an exact diagonalization method. We find that the scattering by the correlated heavy atoms can open a gap in the spectrum of the light atoms, either for strong interaction or small temperatures.