# Suppressing quasiparticle poisoning with a voltage-controlled filter

## TL;DR

This paper demonstrates a voltage-controlled filter in an Al/InAs nanowire system that suppresses quasiparticle poisoning, thereby enhancing charge stability and coherence in quantum devices.

## Contribution

It introduces a gapped segment as a voltage-controlled filter to suppress quasiparticle poisoning in a hybrid nanowire system, improving charge parity stability.

## Key findings

- Poisoning rate reduced below 200 per second
- Strong quantum charge fluctuations observed
- Superconducting coherence length estimated at ~90 nm

## Abstract

We study single-electron charging events in an Al/InAs nanowire hybrid system with deliberately introduced gapless regions. The occupancy of a Coulomb island is detected using a nearby radio-frequency quantum dot as a charge sensor. We demonstrate that a 1 micron gapped segment of the wire can be used to efficiently suppress single electron poisoning of the gapless region and therefore protect the parity of the island while maintaining good electrical contact with a normal lead. In the absence of protection by charging energy, the 1e switching rate can be reduced below 200 per second. In the same configuration, we observe strong quantum charge fluctuations due to exchange of electron pairs between the island and the lead. The magnetic field dependence of the poisoning rate yields a zero-field superconducting coherence length of ~ 90 nm.