Fano effect and Kondo effect in quantum dots formed in strongly coupled quantum wells

TL;DR

This paper investigates quantum transport phenomena in strongly coupled quantum dots formed in separate quantum wells, revealing the Fano and Kondo effects and how magnetic fields influence inter-well coupling.

Contribution

It demonstrates the coexistence of Fano and Kondo effects in coupled quantum wells and explores magnetic field effects on inter-well coupling in a GaAs/AlGaAs heterostructure.

Findings

Observation of Coulomb oscillations forming a honeycomb lattice.

Detection of the Fano effect due to interference paths.

Identification of the Kondo effect probing spin states.

Abstract

We present lateral transport measurements on strongly, vertically coupled quantum dots formed in separate quantum wells in a GaAs/AlGaAs heterostructure. Coulomb oscillations are observed forming a honeycomb lattice consistent with two strongly coupled dots. When the tunnel barriers in the upper well are reduced we observe the Fano effect due to the interfering paths through a resonant state in the lower well and a continuum state in the upper well. In both regimes an in plane magnetic field reduces the coupling between the wells when the magnetic length is comparable to the center to center separation of the wells. We also observe the Kondo effect which allows the spin states of the double dot system to be probed.