# Radio-frequency methods for Majorana-based quantum devices: fast charge sensing and phase diagram mapping

## TL;DR

This paper demonstrates RF reflectometry techniques in Majorana nanowire devices for rapid conductance measurement and charge sensing, enabling faster characterization and topological state detection.

## Contribution

It introduces two RF-based methods for fast conductance and charge measurements in Majorana devices, improving speed and sensitivity over traditional techniques.

## Key findings

- Conductance measurements are ~40 times faster with RF reflectometry.
- RF charge sensing achieves signal-to-noise >3 and 99.8% visibility in 1 μs.
- Detection of charge state crossover indicating topological transition.

## Abstract

Radio-frequency (RF) reflectometry is implemented in hybrid semiconductor-superconductor nanowire systems designed to probe Majorana zero modes. Two approaches are presented. In the first, hybrid nanowire-based devices are part of a resonant circuit, allowing conductance to be measured as a function of several gate voltages ~40 times faster than using conventional low-frequency lock-in methods. In the second, nanowire devices are capacitively coupled to a nearby RF single-electron transistor made from a separate nanowire, allowing RF detection of charge, including charge-only measurement of the crossover from 2e inter-island charge transitions at zero magnetic field to 1e transitions at axial magnetic fields above 0.6 T, where a topological state is expected. Single-electron sensing yields signal-to-noise exceeding 3 and visibility 99.8% for a measurement time of 1 {\mu}s.