Charge oscillations in Quantum Dots: Renormalization group and Hartree method calculations

TL;DR

This paper investigates charge oscillations in a spinless, interacting two-level quantum dot system using renormalization group and Hartree methods, revealing oscillatory behavior in level occupations influenced by gate voltage and tunneling configurations.

Contribution

It introduces a combined renormalization group and Hartree approach to analyze charge oscillations in quantum dots, extending understanding to more general models with variable tunneling signs.

Findings

Charge oscillations occur during gate voltage sweeps.

Oscillations can invert the occupation levels.

Results are qualitatively explained by Hartree analysis.

Abstract

We analyze the local level occupation of a spinless, interacting two-level quantum dot coupled to two leads by means of Wilson's numerical renormalization group method. A gate voltage sweep, causing a rearrangement of the charge such that the system's energy is minimized, leads to oscillations, and sometimes even inversions, in the level occupations. These charge oscillations can be understood qualitatively by a simple Hartree analysis. By allowing a relative sign in one tunneling matrix element between dot and leads, we extend our findings to more generic models.