Non-adiabadic charge pumping in a hybrid SET transistor

TL;DR

This paper theoretically investigates charge quantization in hybrid SET transistors, identifying limitations due to Andreev reflection and cotunneling, and proposes voltage shaping to achieve high-precision current quantization.

Contribution

It introduces a method to improve charge pumping accuracy in hybrid SET transistors by shaping the gate voltage, enabling metrological precision.

Findings

Achieves potential accuracy of 10^{-8} in charge quantization.

Maintains a quantized current of about 30 pA with realistic parameters.

Identifies Andreev reflection and cotunneling as key limiting processes.

Abstract

We study theoretically current quantization in the charge turnstile based on the hybrid (SINIS or NISIN) SET transistor. The quantization accuracy is limited by either Andreev reflection or by Cooper pair - electron cotunneling. The rates of these processes are calculated in the ``above-the-threshold'' regime when they compete directly with the lowest-order tunneling. We show that by shaping the ac gate voltage driving the turnstile, it should be possible to achieve the metrological accuracy of $10^{-8}$, while maintaining the absolute value of the quantized current on the order of 30 pA, just by one turnstile with realistic parameters using aluminium as superconductor.