High-performance gate-controlled superconducting switches: large output voltage and reproducibility

TL;DR

This paper demonstrates highly reproducible gate-controlled superconducting switches with large output voltages, showing independence from constriction width and establishing a correlation with leakage current, advancing superconducting logic technology.

Contribution

It provides the first comprehensive study confirming reproducibility and performance optimization of GCS devices, including larger voltage outputs and insights into leakage current effects.

Findings

GCS is independent of constriction width.

Achieved voltage output exceeds previous reports by at least an order of magnitude.

Leakage current correlates strongly with GCS operation and can modulate device voltage.

Abstract

Logic circuits consist of devices that can be controlled between two distinct states. The recent demonstration that a superconducting current flowing in a constriction can be controlled via a gate voltage ($V_G$) - can lead to superconducting logic with better performance than existing logics. However, before such logic is developed, high reproducibility in the functioning of GCS devices and optimization of their performance must be achieved. Here, we report an investigation of gated Nb devices showing GCS with unprecedently-high reproducibility. Based on the investigation of a statistically-significant number of devices, we demonstrate that the GCS is independent of the constriction width, in contrast with previous reports, and confirm a strong correlation between the GCS and the leakage current ($I_{leak}$) induced by $V_G$. We also achieve a voltage output in our devices larger than the typical values reported to date by at least one order of magnitude, which is relevant for the future interconnection of devices, and show that $I_{leak}$ can be used as a tool to modulate the operational $V_G$ of devices on a $SiO_2$ substrates. These results altogether represent an important step forward towards the optimization of reproducibility and performance of GCS devices, and the future development of a GCS-based logic.