Tunnel conductance spectroscopy via harmonic generation in a hybrid capacitor device

TL;DR

This paper introduces a capacitive method utilizing third-harmonic generation to measure the density of states in nanostructures, enabling non-destructive spectroscopic analysis crucial for detecting Majorana quasiparticles.

Contribution

It presents a novel harmonic generation technique for differential conductance spectroscopy that preserves the low-dimensional properties of nanostructures during measurement.

Findings

Successfully measures density of states beyond the superconducting gap.

Enables detection of Majorana quasiparticles signatures.

Provides a non-destructive alternative to traditional tunneling spectroscopy.

Abstract

We address the measurement of density of states within and beyond the superconducting gap in tunnel-coupled finite-size nanostructures using a capacitive method. Third-harmonic generation is used to yield the full differential conductance spectrum without destruction of the low dimensionality otherwise induced by intimate ohmic coupling to an electrode. The method is particularly relevant to attempts to discern the presence of the fragile Majorana quasiparticle at the end of spin-orbit-coupled nanowires in appropriate magnetic field conditions by their signature mid-gap density of states.