Symmetry-Guided Design of Quantum Couplers in Dirac materials: AA-Bilayer Graphene Coupler

TL;DR

This paper presents a theoretical framework for designing quantum couplers in Dirac materials, enabling polarization control of quasiparticles with perfect transmission conditions, exemplified by AA-stacked bilayer graphene nanoribbons.

Contribution

It introduces a novel theoretical approach for polarization-modulating quantum couplers in Dirac materials, with explicit modeling of AA-bilayer graphene nanoribbons.

Findings

Perfect transmission conditions for polarization channels are identified.

Transmission can be finely tuned by external fields.

The model applies to both narrow and wide couplers.

Abstract

We develop a theoretical framework for designing quantum couplers based on Dirac materials that can modulate the polarization of transmitted quasiparticles without significantly perturbing their propagation. We analyze in detail the conditions required for perfect transmission (Klein tunneling) together with controlled polarization transformation of the incoming states. We then discuss an explicit model of a quantum coupler composed of AA-stacked bilayer graphene nanoribbons with armchair edges and a localized interlayer interaction. Perfect transmission through the desired polarization channels is examined for both narrow and wide couplers. We show that the transmission of polarized states can be finely tuned by external fields.