# Measuring Majorana non-locality and spin structure with a quantum dot

## TL;DR

This paper proposes using a quantum dot as a local spectroscopic tool to directly measure Majorana non-locality and spin structure in nanowires, advancing the experimental validation of topological Majorana modes.

## Contribution

It introduces a novel method employing a quantum dot to quantify Majorana non-locality and probe the spin structure of Majorana wave functions in nanowires.

## Key findings

- Quantum dot can measure Majorana non-locality via local transport.
- Dot states reveal spin polarization at singlet-doublet transitions.
- Method enables indirect measurement of nanowire spin-orbit coupling.

## Abstract

Robust zero bias transport anomalies in semiconducting nanowires with proximity-induced superconductivity have been convincingly demonstrated in various experiments. While these are compatible with the existence of Majorana zero modes at the ends of the nanowire, a direct proof of their non-locality and topological protection is now needed. Here we show that a quantum dot at the end of the nanowire may be used as a powerful spectroscopic tool to quantify the degree of Majorana non-locality through a local transport measurement. Moreover, the spin polarization of dot sub-gap states at singlet-doublet transitions in the Coulomb blockade regime allows the dot to directly probe the spin structure of the Majorana wave function, and indirectly measure the spin-orbit coupling of the nanowire.