# Revealing charge-tunneling processes between a quantum dot and a superconducting island through gate sensing

## TL;DR

This paper demonstrates a method to detect charge-tunneling processes between a quantum dot and a superconducting island using RF gate sensing, revealing spin-dependent quasiparticle and Cooper pair tunneling, and enabling subgap state characterization without transport.

## Contribution

It introduces a novel RF gate sensing technique to directly observe charge-tunneling processes and characterize subgap states in quantum dot-superconductor systems.

## Key findings

- Resolved spin-dependent quasiparticle tunneling
- Detected two-particle Cooper pair tunneling
- Enabled subgap state characterization without transport

## Abstract

We report direct detection of charge-tunneling between a quantum dot and a superconducting island through radio-frequency gate sensing. We are able to resolve spin-dependent quasiparticle tunneling as well as two-particle tunneling involving Cooper pairs. The quantum dot can act as an RF-only sensor to characterize the superconductor addition spectrum, enabling us to access subgap states without transport. Our results provide guidance for future dispersive parity measurements of Majorana modes, which can be realized by detecting the parity-dependent tunneling between dots and islands.