Double-degenerate Fermi mixtures of $^6$Li and $^{53}$Cr atoms

TL;DR

This paper reports the creation of a degenerate mixture of ultracold $^6$Li and $^{53}$Cr atoms, enabling exploration of exotic quantum regimes and potential formation of ultracold polar molecules.

Contribution

It demonstrates a novel all-optical method to produce large, degenerate mixtures of lithium and chromium with tunable densities and degeneracy levels.

Findings

Achieved large, degenerate samples of $^6$Li and $^{53}$Cr with $T/T_{F} \,\approx\, 0.25

Controlled the density and degeneracy independently using a crossed bichromatic optical dipole trap

Enabled potential formation of ultracold paramagnetic polar molecules and dipolar Fermi gases.

Abstract

We report on the realization of a novel degenerate mixture of ultracold fermionic lithium and chromium atoms. Based on an all-optical approach, with an overall duty-cycle of about 13 seconds, we produce large and degenerate samples of more than 2$\times 10^5$ $^6$Li atoms and $10^5$ $^{53}$Cr atoms, with both species exhibiting normalized temperatures of about $T/T_{F}$=0.25. Additionally, through the exploitation of a crossed bichromatic optical dipole trap, we can controllably vary the density and degree of degeneracy of the two components almost independently, and widely tune the lithium-to-chromium density ratio. Our $^{6}$Li-$^{53}$Cr Fermi mixture opens the way to the investigation of a variety of exotic few- and many-body regimes of quantum matter, and it appears as an optimally-suited system to realize ultracold paramagnetic polar molecules, characterized by both electric and magnetic dipole moments. Ultimately, our strategy also provides an efficient pathway to produce dipolar Fermi gases, or spin-mixtures, of ultracold $^{53}$Cr atoms.