Radio-frequency characterization of a supercurrent transistor made from a carbon nanotube

TL;DR

This paper demonstrates radio-frequency reflectometry measurements on a supercurrent transistor made from a carbon nanotube, revealing detailed features of its conductance and impedance that enhance understanding of hybrid superconducting devices.

Contribution

It introduces RF measurement techniques to supercurrent transistors based on carbon nanotubes, providing more sensitive and detailed characterization than traditional DC methods.

Findings

RF measurements resolve conductance features more clearly

Radio-frequency reflectometry detects reactive impedance components

Results improve understanding of superconductor-semiconductor hybrids

Abstract

A supercurrent transistor is a superconductor-semiconductor hybrid device in which the Josephson supercurrent is switched on and off using a gate voltage. While such devices have been studied using DC transport, radio-frequency measurements allow for more sensitive and faster experiments. Here a supercurrent transistor made from a carbon nanotube is measured simultaneously via DC conductance and radio-frequency reflectometry. The radio-frequency measurement resolves all the main features of the conductance data across a wide range of bias and gate voltage, and many of these features are seen more clearly. These results are promising for measuring other kinds of hybrid superconducting devices, in particular for detecting the reactive component of the impedance, which a DC measurement can never detect.