Parity Effects and Higher Order Tunneling in Superconducting SET Transistors

TL;DR

This paper investigates how parity effects influence tunneling in superconducting single-electron transistors, emphasizing the importance of higher order tunneling processes beyond two-electron tunneling, with implications for experimental observations.

Contribution

It provides a theoretical analysis of third and fourth order tunneling processes and their significance in superconducting SETs, extending understanding beyond two-electron tunneling effects.

Findings

Higher order tunneling processes are significant in superconducting SETs.

Parity effects can block single electron tunneling, making higher order processes relevant.

Estimated magnitudes of third and fourth order tunneling processes.

Abstract

Single electron tunneling into small superconducting islands is sensitive to the gap energy of the excitations created in the process and, hence, depends on the parity of the electron number in the island. We study these effects by analyzing the kinetics of the system. Since the interplay of Coulomb blockade and parity effects leads to a blocking of single electron tunneling, higher order tunneling processes become important. This is well-established for two-electron tunneling. Here we study processes of third and fourth order. We estimate the order of magnitude for these processes and discuss their relevance for recent experiments.