Exact crossover Green function in the two-channel and two-impurity Kondo models

TL;DR

This paper analytically calculates the exact zero-temperature crossover Green function in two-channel and two-impurity Kondo models, revealing rich behaviors due to symmetry-breaking perturbations that can be observed experimentally.

Contribution

It provides the first exact analytical Green function for the crossover in these models, validated by numerical renormalization group results.

Findings

Exact Green function matches NRG calculations.

Crossover behavior depends on perturbation mixture.

Observable effects in quantum dot experiments.

Abstract

Symmetry-breaking perturbations destabilize the critical points of the two-channel and two-impurity Kondo models, thereby leading to a crossover from non-Fermi liquid behavior to standard Fermi liquid physics. Here we use an analogy between this crossover and one occurring in the boundary Ising model to calculate the full zero temperature crossover Green function analytically. In remarkable agreement with our numerical renormalization group calculations, the single exact function applies for an arbitrary mixture of the relevant perturbations in each model. This rich behavior resulting from finite channel asymmetry, inter-lead charge transfer and/or magnetic field should be observable in quantum dot or tunneling experiments.