We report on the realization of a Fermi-Fermi mixture of ultracold atoms that
combines mass imbalance, tunability, and collisional stability. In an optically
trapped sample of
161Dy and
40K, we identify a broad Feshbach
resonance centered at a magnetic field of 218
G. In the strongly interacting
regime, we demonstrate hydrodynamic behavior in the expansion after release
from the trap. Lifetime studies on resonance show that the fermionic nature of
the system suppresses inelastic few-body processes by several orders of
magnitude. The resonant mixture opens up intriguing perspectives for studies on
novel states of strongly correlated fermions with mass imbalance.
We investigate the quantum anomalous Hall effect in a mixture of ultracold neutral bosons and fermions held on a hexagonal optical lattice. In the strong atom-atom interaction limit, composite fermions composed of one fermion with bosons or bosonic holes in the mixture are formed. Such composite fermions have already been generated successfully in experiment [Nat. Phys. 7, 642 (2011)]. Here we predict that this kind of composite fermion may provide a realization of the quantum anomalous Hall effect by tuning the atom-atom interaction or the filling of the bosons in the mixture. We also discuss the corresponding experimental signatures of the quantum anomalous Hall effect in the Bose-Fermi mixture on hexagonal optical lattice.