The experimental realization of quantum degenerate cold Fermi gases with large hyperfine spins opens up a new opportunity for exotic many-body physics.
We report the realization of a novel degenerate Fermi mixture with an SUð2Þ Â SUð6Þ symmetry in a cold atomic gas.We successfully cool the mixture of the two fermionic isotopes of ytterbium 171 Yb with the nuclear spin I ¼ 1=2 and 173 Yb with I ¼ 5=2 below the Fermi temperature T F as 0:46T F for 171 Yb and 0:54T F for 173 Yb.The same scattering lengths for different spin components make this mixture featured with the novel SUð2Þ Â SUð6Þ symmetry.The nuclear spin components are separately imaged by exploiting an optical Stern-Gerlach effect.In addition, the mixture is loaded into a 3D optical lattice to implement the SUð2Þ Â SUð6Þ Hubbard model.This mixture will open the door to the study of novel quantum phases such as a spinor Bardeen-Cooper-Schrieffer-like fermionic superfluid.
Recently, cold atomic Fermi gases with the large magnetic dipolar interaction have been laser cooled down to quantum degeneracy. Different from electric-dipoles which are classic vectors, atomic magnetic dipoles are quantum-mechanical matrix operators proportional to the hyperfine-spin of atoms, thus provide rich opportunities to investigate exotic many-body physics. Furthermore, unlike anisotropic electric dipolar gases, unpolarized magnetic dipolar systems are isotropic under simultaneous spin-orbit rotation. These features give rise to a robust mechanism for a novel pairing symmetry: orbital p-wave (L = 1) spin triplet (S = 1) pairing with total angular momentum of the Cooper pair J = 1. This pairing is markedly different from both the (3)He-B phase in which J = 0 and the (3)He-A phase in which J is not conserved. It is also different from the p-wave pairing in the single-component electric dipolar systems in which the spin degree of freedom is frozen.
We report on the realization of a degenerate mixture of ultracold fermionic lithium and chromium atoms. Based on an all-optical approach, with an overall duty cycle of about 13 s, we produce large and degenerate samples of more than $2\ifmmode\times\else\texttimes\fi{}{10}^{5}{\phantom{\rule{4pt}{0ex}}}^{6}\mathrm{Li}$ atoms and ${10}^{5}^{53}\mathrm{Cr}$ atoms, with both species exhibiting normalized temperatures of about T/TF=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 $^{6}\mathrm{Li}\text{\ensuremath{-}}^{53}\mathrm{Cr}$ 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 53Cr atoms.