Study of Josephson-Quasiparticle Cycles in Superconducting Single-Electron Transistors

Abstract

We have investigated the charge transport through superconducting single-electron transistors. With a sample which has large charging energy E c> Δ, where Δ is a superconducting energy gap of the electrodes, we studied the positions of the so-called Josephson-quasiparticle (JQP) peaks. We demonstrate that the JQP cycles coexist with the normal quasiparticle current even at the bias voltages above the Coulomb blockade threshold. Bias voltage conditions for observing these peaks are also classified for various parameter regions.