Realization of GHz-frequency impedance matching circuits for nano-scale devices

TL;DR

This paper demonstrates GHz-frequency impedance matching circuits using superconducting transmission lines for nano-scale device measurements, enabling high-resolution RF transport analysis with improved signal quality.

Contribution

It presents the design and realization of superconducting impedance transformers for 2-10 GHz, specifically applied to nano-scale devices like gold break junctions.

Findings

Impedance matching circuits operate effectively at 6 GHz.

RF impedance measurements agree with DC resistance.

Achieved bandwidth of 45 MHz for microwave reflectometry.

Abstract

Integrating nano-scale objects, such as single molecules or carbon nanotubes, into impedance transformers and performing radio-frequency measurements allows for high time-resolution transport measurements with improved signal-to-noise ratios. The realization of such transformers implemented with superconducting transmission lines for the 2-10 GHz frequency range is presented here. Controlled electromigration of an integrated gold break junction is used to characterize a 6 GHz impedance matching device. The real part of the RF impedance of the break junction extracted from microwave reflectometry at a maximum bandwidth of 45 MHz of the matching circuit is in good agreement with the measured direct current resistance.