Realization of resonantly interacting Fermi mixtures of ⁶Li and ⁵³Cr atoms

We report on the realization of resonantly interacting Fermi mixtures of ⁶Li and ⁵³Cr atoms. 

Employing a set of 50 Feshbach resonances, observed in several spin combinations between 0G and 1500G, we develop an accurate quantum collisional model for our system. From this we derive scattering lengths and unobserved resonance locations for ⁶Li-⁵³Cr, and provide accurate predictions for the collisional properties of other Li-Cr isotopic pairs.

A set of strong s-wave resonances, essentially immune to two-body inelastic losses, are identified at about 1.4kG.

We measure the magnetic field width of one among these features to be about 0.5G, in agreement with our model prediction.

Exploiting the same resonance, we show resonant tuning of inter-species elastic interactions, characterized through radio-frequency spectroscopy protocols.

Finally, we discuss our all-optical route to reach simultaneous quantum degeneracy in our mixture, comprising about 2.2x10⁵ Li atoms at T/T_F=0.3 and 6x10⁴ Cr atoms at T/T_F=0.9, respectively.

Our work paves the way to the observation of novel few- and many-body phenomena in mass-imbalanced Fermi gases, and to the realization of ultracold samples of LiCr ground-state molecules featuring both electric and magnetic dipole moments.