Impurity problem of alkaline-earth-like atoms near an orbital Feshbach resonance

Abstract

In recent years, alkaline-earth and alkaline-earth-like atoms have attracted much research interest in the field of ultracold atom. Especially, the recently discovered orbital Feshbach resonance makes it possible to investigate a strongly interacting gas of alkaline-earth or alkaline-earth-like atoms, which has greatly enriched the scope of quantum simulation in these systems. This paper focuses on the impurity problem in a Fermi gas of <sup>173</sup>Yb atoms near orbital Feshbach resonance. In this problem, the impurity atom in <sup>3</sup><i>P</i><sub>0</sub> state will interact with the background Fermi sea in the ground state and the molecule or polaron state will be produced out of the Fermi sea. By using the Chevy-like ansatz, we investigate the properties of the molecule and attractive polaron states firstly and a transition between these two states will be found. Then, some properties of the repulsive polaron state will be introduced, such as the effective mass and the decay rate. Furthermore, the effect of an additional Fermi sea will be considered in this system. Finally, we will discuss the impurity problem in a two-dimensional system.

Polaron and molecular states of a spin-orbit coupled impurity in a spinless Fermi sea*

“…Note that for Ω = 0, the one-dimensional SOC can be gauged away and one gets the usual critical value of −(1/k F a s ) ∼ −3.65 without SOC. Compared to the previous work [61][62][63][64] where molecule states with a finite c.m. momentum are induced by the SOC, here in our case, the one-dimensional SOC of the impurity has more profound effect on the polaron state than the molecule state.…”

“…[45] Recent years, the implementation of spin-orbit coupling (SOC) in ultracold gases [46][47][48][49][50] stimulates tremendous researches on the nontrivial effects brought by SOC, [51][52][53][54][55][56][57][58][59][60] which also enriches the content of the impurity physics in cold atom systems. [61][62][63][64] In general, SOC mixes different spin components of the atom and changes the single-particle dispersion dramatically, which may lead to the enhanced lowenergy density of state and possible single-particle groundstate degeneracy [46,60] responsible for the many-body behaviors of the underlying systems. A series of Fulde-Ferrell-Larkin-Ovchinnikov-like molecule states are predicted in different impurity models with SOC.…”