Kondo Polarons in a One-Dimensional Fermi Gas

We consider the motion of a spin-$1/2$ impurity in a one-dimensional gas of spin-$1/2$ fermions. For antiferromagnetic interaction between the impurity and the fermions, the low temperature behavior of the system is governed by the two-channel Kondo effect, leading to the impurity becoming completely opaque to the spin excitations of the gas. As well as the known spectral signatures of the two-channel Kondo effect, we find that the low temperature mobility of the resulting “Kondo polaron” takes the universal form $\mu \to 3\hslash v_F^2/2\pi k_B^2{T}^2$, in sharp contrast to the spinless case where $\mu \propto T^{-4}$.

Figure 1

Second order particle-particle (top) and particle-hole (bottom) contributions to the effective spin-spin interaction between the fermions (solid lines) and impurity (dashed lines).