Coulomb Blockade in a Quantum Dot Coupled Strongly to a Lead

TL;DR

This paper theoretically investigates Coulomb blockade phenomena in a quantum dot strongly coupled to a lead in the quantum Hall regime, revealing persistent blockade features and oscillations in conductance and capacitance.

Contribution

It introduces models showing Coulomb blockade effects persist even with perfect transmission and predicts measurable oscillations in conductance and capacitance as functions of gate voltage.

Findings

Coulomb blockade features persist despite perfect transmission.

Oscillations in tunneling conductance and capacitance are predicted.

The ratio of fractional oscillations is an intrinsic property of the quantum dot.

Abstract

We study theoretically a quantum dot in the quantum Hall regime that is strongly coupled to a single lead via a point contact. We find that even when the transmission through the point contact is perfect, important features of the Coulomb blockade persist. In particular, the tunneling into the dot via a second weakly coupled lead is suppressed, and shows features which can be ascribed to elastic or inelastic cotunneling through the dot. When there is weak backscattering at the point contact, both the tunneling conductance and the differential capacitance are predicted to oscillate as a function of gate voltage. We point out that the dimensionless ratio $\xi$ between the fractional oscillations in $G$ and $C$ is an intrinsic property of the dot, which, in principle, can be measured. We compute $\xi$ within two models of electron-electron interactions. In addition, we discuss the role of additional channels.