Two-channel Kondo physics in two-impurity Kondo models

TL;DR

This paper analyzes the non-Fermi liquid quantum critical state of the two-impurity Kondo model with spin-S, using conformal field theory and NRG, revealing its equivalence to the two-channel Kondo model and identifying conductance signatures.

Contribution

It demonstrates the critical point of the spin-S two-impurity Kondo model is identical to that of the two-channel Kondo model with potential scattering, across all spins.

Findings

Critical point matches that of the two-channel Kondo model.

Distinct conductance signatures depend on device asymmetry.

Square-root conductance behavior appears only in certain regimes.

Abstract

We consider the non-Fermi liquid quantum critical state of the spin-S two-impurity Kondo model, and its potential realization in a quantum dot device. Using conformal field theory (CFT) and the numerical renormalization group (NRG), we show the critical point to be identical to that of the two-channel Kondo model with additional potential scattering, for any spin-S. Distinct conductance signatures are shown to arise as a function of device asymmetry; with the `smoking gun' square-root behavior, commonly believed to arise at low-energies, dominant only in certain regimes.