Klein-tunneling-enhanced directional coupler for Dirac electron wave in graphene

TL;DR

This paper demonstrates that Klein tunneling significantly enhances directional coupling in graphene waveguides, enabling efficient electron transfer and potential for compact quantum electronic devices.

Contribution

It introduces a novel coupling structure in graphene utilizing Klein tunneling to improve electron transfer efficiency and device miniaturization.

Findings

Klein tunneling greatly increases coupling strength.

Complete electron transfer achieved within hundreds of nanometers.

Potential for scalable graphene-based quantum devices.

Abstract

Using the coupled-mode theory in guided-wave optics and electronics, we explore a directional coupling structure composed of two parallel waveguides electrostatically induced by the split-gate technique in bulk graphene. Our results show that Klein tunneling can greatly enhance the coupling strength of the structure. By adjusting a gate voltage, the probability density of Dirac electron wave function initially in one waveguide can be completely transferred into the other waveguide within several hundred nanometers. Our findings could not only lead to functional coherent coupling devices for quantum-based electronic signal processing and on-chip device integration in graphene, but also shrink the size of the devices to facilitate the fabrication of graphene-based large-scale integrated logic circuits.