Quantitative study of quasiparticle traps using the single-Cooper-pair transistor

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 10²- to 10³-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.