A quantitative study of quasiparticle traps using the single-Cooper-pair-transistor

TL;DR

This study quantitatively examines how quasiparticle traps affect tunneling rates in single-Cooper-pair-transistors using radio-frequency reflectometry, demonstrating significant reductions in tunneling with traps.

Contribution

It provides the first quantitative measurement of quasiparticle trapping effects on tunneling rates in these devices, highlighting the effectiveness of traps.

Findings

Quasiparticle traps reduce tunneling rates by 100-1000 times.

Traps decrease both on-island and off-island quasiparticle tunneling.

Significant suppression of quasiparticle activity improves device stability.

Abstract

We use radio-frequency reflectometry to measure quasiparticle tunneling rates in the single-Cooper-pair-transistor. Devices with and without quasiparticle traps in proximity to the island are studied. A $10^2$ to $10^3$-fold reduction in the quasiparticle tunneling rate onto the island is observed in the case of quasiparticle traps. In the quasiparticle trap samples we also measure a commensurate decrease in quasiparticle tunneling rate off the island.