Kondo polarons in a one-dimensional Fermi gas

TL;DR

This paper investigates a one-dimensional Fermi gas with a spin-1/2 impurity, revealing how the two-channel Kondo effect influences the impurity's behavior, spectral properties, and mobility at low temperatures.

Contribution

It demonstrates the emergence of the two-channel Kondo effect in a 1D Fermi gas with a spin-1/2 impurity and derives the universal low-temperature mobility of the Kondo polaron.

Findings

Impurity becomes opaque to spin excitations due to the Kondo effect.

The low-temperature mobility follows a universal $T^{-2}$ law.

Spectral signatures confirm the two-channel Kondo physics.

Abstract

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 $\mu\to \frac{3\hbar v_F^2}{2\pi k_B^2T^2}$, in sharp contrast to the spinless case where $\mu\propto T^{-4}$.