Coherent transient transport of interacting electrons through a quantum waveguide switch

TL;DR

This paper studies coherent electron transport in a double quantum waveguide system, revealing how tuning the coupling window and external magnetic fields can control electron flow and enable quantum logic operations.

Contribution

It demonstrates how to manipulate transient electron transport in coupled quantum waveguides using coupling window length and magnetic fields, highlighting potential for quantum device applications.

Findings

Oscillations in charge current with coupling window tuning

Resonance conditions maximize electron conductance

Magnetic fields and quantum dots enhance inter-waveguide transport

Abstract

We investigate coherent electron-switching transport in a double quantum waveguide system in a perpendicular static or vanishing magnetic field. The finite symmetric double waveguide is connected to two semi-infinite leads from both ends. The double waveguide can be defined as two parallel finite quantum wires or waveguides coupled via a window to facilitate coherent electron inter-wire transport. By tuning the length of the coupling window, we observe oscillations in the net charge current and a maximum electron conductance for the energy levels of the two waveguides in resonance. The importance of the mutual Coulomb interaction between the electrons and the influence of two-electron states is clarified by comparing results with and without the interaction. Even though the Coulomb interaction can lift two-electron states out of the group of active transport states the length of the coupling window can be tuned to locate two very distinct transport modes in the system in the late transient regime before the onset of a steady state. A static external magnetic field and quantum-dots formed by side gates (side quantum dots) can be used to enhance the inter-waveguide transport which can serve to implement a quantum logic device. The fact that the device can be operated in the transient regime can be used to enhance its speed.