Microsecond resolution of quasiparticle tunneling in the single-Cooper-pair transistor.

We present radio-frequency measurements on a single-Cooper-pair-transistor in which individual quasiparticle poisoning events were observed with microsecond temporal resolution. Thermal activation of the quasiparticle dynamics is investigated, and consequently, we are able to determine energetics of the poisoning and unpoisoning processes. In particular, we are able to assign an effective quasiparticle temperature to parametrize the poisoning rate.