Tuning Fano-type resonances in coupled quantum point contacts by applying asymmetric voltages

TL;DR

This paper investigates how asymmetric voltages applied to coupled quantum point contacts can tune Fano-type resonances, revealing controllable interference effects in quantum transport through a double QPC device.

Contribution

It demonstrates the control of Fano resonances in a double quantum point contact system via asymmetric voltage application, supported by experimental and theoretical analysis.

Findings

Reproduces zero-field quantized conductance and interference phenomena.

Identifies Fano resonances arising from localized states and inter-edge coupling.

Predicts control of Fano resonances through asymmetric confinement.

Abstract

We study the ballistic magnetotransport in a double quantum point contact (QPC) device consisting of a quasi-one-dimensional quantum wire with an embedded island-like impurity - etched nano-hole as in a recently published experiment [J. C. Chen, Y. Lin, K.-T. Lin, T. Ueda and S. Komiyama, Appl. Phys. Lett. 94, 012105 (2009)]. We reproduce the zero field quantized conductance, the interference phenomenon induced by the coupled QPCs, as well as the Ramsauer-like resonances observed in the experiments. At finite magnetic fields Fano-type resonances arises in the conductance due to the formation of localized states at the impurity periphery and to an inter-edge state resonant coupling effect. It is predicted that the Fano-type resonances can be controlled by an asymmetric confinement of the QPCs.