Effective level attraction and magnetic flux-induced negative differential conductance in two double quantum dot molecules embedded in an Aharonov-Bohm ring

TL;DR

This paper investigates electron transport in double quantum dot molecules within an Aharonov-Bohm ring, revealing flux-dependent level attraction, perfect transmission lines, and two types of negative differential conductance with distinct origins.

Contribution

It demonstrates magnetic flux-induced level attraction and negative differential conductance in a double quantum dot system, expanding understanding of quantum interference effects.

Findings

Bound states in the continuum and transmission suppression at equilibrium.

Magnetic flux-dependent effective level attraction and perfect transmission lines.

Two types of negative differential conductance observed out of equilibrium.

Abstract

We study transport of non-interacting electrons through two quantum dot molecules embedded in an Aharonov-Bohm interferometer. The system in equilibrium exhibits bound states in the continuum (BIC) and total suppression of transmission. It also shows a magnetic flux-dependent effective level attraction and lines of perfect transmission when the intramolecular coupling is weak. Out of equilibrium, the current displays two kind of negative differential conductance (NDC) regions, which have different origins. One is generated by the usual mechanism of the NDC arising in a double quantum dot system. The other is induced by the magnetic flux, and it occurs at small voltages and for a well definite range of the intramolecular couplings. We explain this effect in terms of the level attraction displayed by the system.