Super-ballistic transport in an open quantum ring

TL;DR

This paper reports the discovery of super-ballistic transport in open quantum rings, driven by quantum interference effects near eigenenergies, which exceeds traditional ballistic limits and is unique to such quantum systems.

Contribution

It reveals the existence of super-ballistic transport in open quantum rings due to quantum interference, a phenomenon not observed in linear quantum junctions.

Findings

Super-ballistic transport occurs near eigenenergies of the ring-Hamiltonian.

Quantum interference between counter-propagating waves causes this phenomenon.

The effect depends on the ring-to-lead configuration.

Abstract

When the degeneracies of the ring-Hamiltonian are removed by the asymmetric ring-to-electrodes configuration for an open quantum ring (OQR), the overall junction transmission function exhibits fano-type antiresonance, resulting a net circular current appears within the channel, that is the ring around the degenerate energy levels of the ring-Hamiltonian. We investigate the system size scaling properties of the channel conductance and the overall junction conductance of an OQR. Ballistic transport is the unhindered flow of a charge carrier within a conductor. Here we find beyond-ballistic transport near both the degenerate and non-degenerate eigenenergies of the ring-Hamiltonian, depending on the ring-to-lead configuration. This is a purely OQR phenomenon associated with the quantum interference effect between two counter-propagating electronic waves having nearly equal and opposite momenta. Thus there is no equivalent phenomenon in open quantum junctions with linear channel.