Mesoscopic conductance fluctuations in a coupled quantum dot system

TL;DR

This paper investigates mesoscopic conductance fluctuations in a coupled quantum dot system within an Aharonov-Bohm ring, revealing how quantum interference and chaos influence transport properties and resonance behavior.

Contribution

It introduces a model combining a well-defined resonant quantum dot with a chaotic one using random matrix theory, analyzing how fluctuations affect conductance and resonance shapes.

Findings

Resonant peaks can turn into antiresonances with increased level broadening.

Magnetic flux can control the symmetry of the Fano resonance.

Conductance fluctuations significantly influence the transport properties.

Abstract

We study the transport properties of an Aharonov-Bohm ring containing two quantum dots. One of the dots has well-separated resonant levels, while the other is chaotic and is treated by random matrix theory. We find that the conductance through the ring is significantly affected by mesoscopic fluctuations. The Breit-Wigner resonant peak is changed to an antiresonance by increasing the ratio of the level broadening to the mean level spacing of the random dot. The asymmetric Fano form turns into a symmetric one and the resonant peak can be controlled by magnetic flux. The conductance distribution function clearly shows the influence of strong fluctuations.