Hybrid single-electron transistor as a source of quantized electric current

TL;DR

This paper proposes a hybrid metal-superconductor single-electron transistor as a robust, quantized current source with potential for quantum metrology, demonstrating multiple current plateaus at levels of ef.

Contribution

It introduces and theoretically validates a novel hybrid turnstile device capable of producing quantized current with high accuracy for quantum metrology.

Findings

Demonstrates current plateaus at multiples of ef within measurement uncertainty

Theoretical estimates suggest errors can be minimized through device optimization

Proposes a feasible approach for a quantum standard of electric current

Abstract

The basis of synchronous manipulation of individual electrons in solid-state devices was laid by the rise of single-electronics about two decades ago. Ultra-small structures in a low temperature environment form an ideal domain of addressing electrons one by one. A long-standing challenge in this field has been the realization of a source of electric current that is accurately related to the operation frequency $f$. There is an urgent call for a quantum standard of electric current and for the so-called metrological triangle, where voltage from Josephson effect and resistance from quantum Hall effect are tested against current via Ohm's law for a consistency check of the fundamental constants of Nature, $\hbar$ and $e$. Several attempts to create a metrological current source that would comply with the demanding criteria of extreme accuracy, high yield, and implementation with not too many control parameters have been reported. However, no satisfactory solution exists as yet despite many ingenious achievements that have been witnessed over the years. Here we propose and prove the unexpected concept of a hybrid metal-superconductor turnstile in the form of a one-island single-electron transistor with one gate, which demonstrates robust current plateaus at multiple levels of $ef$ within the uncertainty of our current measurement. Our theoretical estimates show that the errors of the present system can be efficiently suppressed by further optimizations of design and proper choice of the device parameters and therefore we expect it to eventually meet the stringent specifications of quantum metrology.