AC transport in Correlated Quantum Dots: From Kondo to Coulomb blockade regime

TL;DR

This paper investigates how an AC field affects the conductance of a correlated quantum dot across different regimes, revealing suppression of the Kondo plateau, shifted photon-assisted peaks, and smoothing of Coulomb blockade edges.

Contribution

It introduces a real-time i-DFT simulation approach to analyze AC transport in quantum dots, capturing effects across multiple regimes with high computational efficiency.

Findings

Suppression of the zero-temperature Kondo plateau.

Shift of photon-assisted conductance peaks due to correlations.

Smoothing of Coulomb blockade diamond edges.

Abstract

We explore the finite bias DC differential conductance of a correlated quantum dot under the influence of an AC field, from the low-temperature Kondo to the finite temperature Coulomb blockade regime. Real-time simulations are performed using a time-dependent generalization of the steady-state density functional theory (i-DFT) [Nano Lett. {\bf 15}, 8020 (2015)]. The numerical simplicity of i-DFT allows for unprecedented long time evolutions. Accurate values of average current and density are obtained by integrating over several periods of the AC field. We find that (i) the zero-temperature Kondo plateau is suppressed, (ii) the photon-assisted conductance peaks are shifted due to correlations and (iii) the Coulomb blockade is lifted with a concomitant smoothening of the sharp diamond edges.