Fabry-P\'erot interferometry with gate-tunable 3D topological insulator nanowires

TL;DR

This paper investigates the transport properties of a gated 3D topological insulator nanowire forming a Fabry-Pérot interferometer, demonstrating tunable surface-state filtering and potential applications in topological quantum computing.

Contribution

It introduces a novel gated nanowire setup that enables control over surface-state interference patterns and explores their interplay with magnetic fields and asymmetries.

Findings

Controlled Fabry-Pérot interference patterns in 3D TI nanowires.

Ability to filter or transmit specific topological surface states.

Potential for realizing topological superconductivity and Majorana states.

Abstract

Three-dimensional topological insulator (3D TI) nanowires display various interesting magnetotransport properties that can be attributed to their spin-momentum-locked surface states such as quasiballistic transport and Aharonov-Bohm oscillations. Here, we focus on the transport properties of a 3D TI nanowire with a gated section that forms an electronic Fabry-P\'erot (FP) interferometer that can be tuned to act as a surface-state filter or energy barrier. By tuning the carrier density and length of the gated section of the wire, the interference pattern can be controlled and the nanowire can become fully transparent for certain topological surface-state input modes while completely filtering out others. We also consider the interplay of FP interference with an external magnetic field, with which Klein tunneling can be induced, and transverse asymmetry of the gated section, e.g., due to a top-gated structure, which displays an interesting analogy with Rashba nanowires. Due to its rich conductance phenomenology, we propose a 3D TI nanowire with gated section as an ideal setup for a detailed transport-based characterization of 3D TI nanowire surface states near the Dirac point, which could be useful towards realizing 3D TI nanowire-based topological superconductivity and Majorana bound states.