A circuit analysis of an in situ tunable radio-frequency quantum point contact

TL;DR

This paper provides a detailed circuit analysis of a tunable RF quantum point contact setup, examining how circuit parameters affect resonance, noise, and signal quality, with experimental validation.

Contribution

It offers a comprehensive analysis of the influence of circuit components on the tunability and noise performance of RF quantum point contacts, including experimental comparison.

Findings

Resonance frequency depends on series capacitance.

Matching conditions optimize charge detection.

Noise contributions are quantitatively analyzed.

Abstract

A detailed analysis of the tunability of a radio-frequency quantum point contact setup using a C-LCR circuit is presented. We calculate how the series capacitance influences resonance frequency and charge-detector resistance for which matching is achieved as well as the voltage and power delivered to the load. Furthermore, we compute the noise contributions in the system and compare our findings with measurements taken with an etched quantum point contact. While our considerations mostly focus on our specific choice of matching circuit, the discussion of the influence of source-to-load power transfer on the signal-to-noise ratio is valid generally.