Model for overscreened Kondo effect in ultracold Fermi gas

Abstract

The feasibility of realizing overscreened Kondo effect in ultra-cold Fermi gas of atoms with spin s ≥ 3 2 in the presence of a localized magnetic impurity atom is proved realistic. Specifying (as a mere example), to a system of ultra cold 22 Na Fermi gas and a trapped 197 Au impurity, the mechanism of exchange interaction between the Na and Au atoms is elucidated and the exchange constant is found to be positive (antiferromagnetic). The corresponding exchange Hamiltonian is derived, and the Kondo temperature is estimated at the order of 1 µK. Within a weak-coupling renormalization group scheme, it is shown that the coupling renormalizes to the non-Fermi liquid fixed point. An observable displaying multi-channel features even in the weak coupling regime is the impurity magnetization: For T ≫ TK it is negative, and then it increases to become positive with decreasing temperature.

Enhancing Kondo coupling in alkaline-earth-metal atomic gases with confinement-induced resonances in mixed dimensions

“…Exploring these phenomena with cold atom systems have a list of advantages, for instance, one can access physical quantities that have not been measured before in their condensed matter realizations, and one can also study non-equilibrium dynamics in a highly controllable way. However, until now there is still one important category that has not been experimentally realized with cold atom systems yet, despite of quite a few existing proposals [5][6][7][8][9][10][11][12][13][14], and that is the Kondo physics.The Kondo model describes the spin-exchanging interaction between localized impurities and the itinerant fermions [15]. The alkaline-earth atomic gases have natural advantages for performing quantum simulation of the Kondo model.…”

Coqblin-Schrieffer model for an ultracold gas of ytterbium atoms with metastable state

“…Ever since its discovery, the physics exposed in cold atom systems proves to be a godsend for elucidating spectacular physical phenomena that are otherwise extremely difficult to access elsewhere 1-21 . Special attention is recently focused on quantum magnetism in general, and impurity problems in particular [22][23][24][25][26][27][28][29] . One of the reasons is that a cold atom system opens a way to study the physical properties of a gas of fermionic atoms with halfinteger spin s ≥ 3 2 , thereby enabling the study of novel impurity problems.…”

Transport measurement of the orbital Kondo effect with ultracold atoms

“…Our study is based on the simple and versatile scheme to realize the orbital Kondo effect with ultracold atoms [22] (see Refs. [23][24][25][26][27][28][29][30][31][32][33] for other proposals). The system consists of a Fermi sea of spin-polarized ↑ fermions of species A interacting with a spinless impurity atom of different species B which is loaded into a ground state of an isotropic potential.…”