Efimov-enhanced Kondo effect in alkali-metal and alkaline-earth-metal atomic gas mixtures

Abstract

Recent experiment has observed Feshbach resonances between alkaline and alkaline-earth atoms. These Feshbach resonances are insensitive to the nuclear spin of alkaline-earth atoms. Ultilizing this feature, we propose to take this system as a candidate to perform quantum simulation of the Kondo effect. An alkaline atom can form a molecule with an alkaline-earth atom with different nuclear spins, which plays the role of spin-exchange scattering responsible for the Kondo effect. Furthermore, we point out that the existence of three-body bound state and atom-molecule resonance due to the Efimov effect can enhance this spin-exchange scattering, and therefore enhance the Kondo effect. We discuss this mechanism first with a three-body problem in free space, and then demonstrate that the same mechanism still holds when the alkaline atom is localized by an external trap and becomes an impurity embedded in the alkaline-earth atomic gases.