Effect of cross capacitance in three-junction single-electron transistors

The transport properties of an (Formula presented) three-junction single-electron transistor in the superconducting state were studied. Electrostatic coupling between different islands leads to a splitting of the peak in the Coulomb oscillations of the quasiparticle tunneling current. Also observed is a clear beating of the Coulomb oscillations, which is attributed to the cross capacitance between a gate electrode and neighboring island. Numerical calculations based on the orthodox theory with inclusion of cross capacitance reproduce well most of the features seen in our data.