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.

Feshbach Resonances in p -Wave Three-Body Recombination within Fermi-Fermi Mixtures of Open-Shell Li6 and Closed-Shell Green1, Li2, Toh3 et al. 2020Phys. Rev. X541270View full textAdd to dashboardCite

“…Quantum-degenerate mass-imbalanced mixtures [20][21][22] are of interest for several reasons. For instance, they can be used to investigate impurity physics [23][24][25], to study Fermi-Fermi mixtures [26][27][28], and to provide a platform for the simulation of the Kondo effect [29].…”

Phase diagram and dynamics of the SU(N) symmetric Kondo lattice model

“…From a practical point of view, there are three crucial features required for the realization of the SU(N ) Kondo physics in such setups: (i) the existence of a metastable excited state playing together with the atomic ground state the role of orbital degrees of freedom loaded into an orbital state-dependent optical lattice [35], (ii) a large nuclear spin I > 1/2 of fermionic isotopes must decouple from the electronic degrees of freedom to guarantee the SU(N = 2I + 1) spin-rotation symmetry of the interactions, and (iii) an antiferromagnetic (AF) character of spin-exchange interactions in the limit with one fully localized orbital. Although the currently used isotopes with I > 1/2 realize ferromagnetic interorbital interactions [32][33][34][35], ongoing theoretical proposals [36][37][38][39][40], numerical simulations [41][42][43], and utilizing other isotopes of alkali-earth-like atoms [44] allow one to envisage a controllable implementation of a Kondo-singlet state with SU(N ) symmetric interactions in single-impurity and lattice situations in the near future.…”

Experimental study of tune-out wavelengths for spin-dependent optical lattice in $^{87}$Rb Bose-Einstein condensation

“…This system can be a test-bed for observing or simulating phenomena such as entropy cooling [20,52,55,56,61], Kondo effect [62,63] etc, and even have application in Sr optical lattice clock [64].…”