Is the Fano Antiresonance a Necessary Requirement for Circulating Currents in Mesoscopic Interferometers?

TL;DR

This paper investigates the conditions under which circulating currents occur in mesoscopic interferometers, revealing that Fano antiresonances are not always necessary and identifying critical asymmetries that induce them.

Contribution

It demonstrates that circulating currents can arise without Fano antiresonances and identifies the critical arm length asymmetry needed for their appearance.

Findings

Circulating currents can occur without Fano antiresonances.

A critical asymmetry in arm lengths induces Fano antiresonances.

Fano antiresonances depend on arm length asymmetry.

Abstract

Coherent quantum tunneling effects on quantum interference are investigated in electron transport through a mesoscopic interferometer. An evanescent wave tunneling through a potential barrier in one arm can interfere with a propagating wave passing through the other arm of interferometer. It is shown that, even for the same arm lengths, such a quantum interference can induce a circulating current, where Fano antiresonances do not occur in electron transmission. It is found that there exists a critical value of asymmetric arm lengths that gives rise to a Fano antiresonance in electron transmission for the quantum interference between evanescent and propagating waves. We discuss the effects of Fano antiresonances originating from the asymmetric arm lengths on circulating currents.