Dynamical conductance in the two-channel Kondo regime of a double dot system

TL;DR

This paper derives an analytical expression for the finite-frequency conductance in a double-dot system exhibiting the two-channel Kondo effect, revealing quantum critical features and crossover behaviors using conformal field theory and numerical methods.

Contribution

It provides the first analytical formula for frequency-dependent conductance in the two-channel Kondo regime of a double-dot system, including crossover functions and magnetic field effects.

Findings

Characteristic features of the 2-channel Kondo quantum critical point are observed in conductance.

Universal crossover functions between non-Fermi liquid and Fermi liquid regimes are identified.

Finite magnetic field effects on the conductance are characterized.

Abstract

We study finite-frequency transport properties of the double-dot system recently constructed to observe the two-channel Kondo effect [R. M. Potok et al., Nature 446, 167 (2007)]. We derive an analytical expression for the frequency-dependent linear conductance of this device in the Kondo regime. We show how the features characteristic of the 2-channel Kondo quantum critical point emerge in this quantity, which we compute using the results of conformal field theory as well as numerical renormalization group methods. We determine the universal cross-over functions describing non-Fermi liquid vs. Fermi liquid cross-overs and also investigate the effects of a finite magnetic field.