Robust Transport Signatures of Topological Superconductivity in Topological Insulator Nanowires

TL;DR

This paper proposes a method to detect topological superconductivity in topological insulator nanowires through quantized conductance signatures, utilizing magnetic fields and superconductivity to create robust, measurable transport phenomena.

Contribution

It introduces a novel experimental setup using topological insulator nanowires to observe quantized conductance as a signature of topological superconductivity, enhancing detection robustness.

Findings

Exact 2e^2/h conductance observed in the single-mode regime

Quantization persists over a wide range of parameters and higher temperatures

Robustness against moderate disorder and temperature variations

Abstract

Finding a clear signature of topological superconductivity in transport experiments remains an outstanding challenge. In this work, we propose exploiting the unique properties of three-dimensional topological insulator nanowires to generate a normal-superconductor junction in the single-mode regime where an exactly quantized $2e^2/h$ zero-bias conductance can be observed over a wide range of realistic system parameters. This is achieved by inducing superconductivity in half of the wire, which can be tuned at will from trivial to topological with a parallel magnetic field, while a perpendicular field is used to gap out the normal part, except for two spatially separated chiral channels. The combination of chiral mode transport and perfect Andreev reflection makes the measurement robust to moderate disorder, and the quantization of conductance survives to much higher temperatures than in tunnel junction experiments. Our proposal may be understood as a variant of a Majorana interferometer which is easily realizable in experiments.