Charge Sensitivity of Superconducting Single-Electron Transistor

TL;DR

This paper demonstrates that superconducting single-electron transistors can achieve higher charge sensitivity than normal-metal or semiconductor devices due to the superconducting energy gap's properties, with implications for improved operation at higher temperatures.

Contribution

It introduces the concept that superconducting energy gaps enhance charge sensitivity and discusses new features in the I-V characteristics of SISIS structures.

Findings

Superconducting transistors have higher charge sensitivity near quasiparticle tunneling threshold.

Superconductivity allows operation at higher temperatures compared to normal devices.

A new peak-like feature on the I-V curve of SISIS structures is identified.

Abstract

It is shown that the noise-limited charge sensitivity of a single-electron transistor using superconductors (of either $SISIS$ or $NISIN$ type) operating near the threshold of quasiparticle tunneling, can be considerably higher than that of a similar transistor made of normal metals or semiconductors. The reason is that the superconducting energy gap, in contrast to the Coulomb blockade, is not smeared by the finite temperature. We discuss also the increase of the maximum operation temperature due to superconductivity and a new peak-like feature on the $I-V$ curve of $SISIS$ structures.