4.2 K Sensitivity-Tunable Radio Frequency Reflectometry of a Physically Defined P-channel Silicon Quantum Dot

TL;DR

This paper presents a sensitive, tunable RF reflectometry technique for measuring silicon quantum dots at cryogenic temperatures, enhancing readout speed and sensitivity for quantum computing architectures.

Contribution

It introduces a novel RF reflectometry circuit with tunable varactors for improved measurement of silicon quantum dots at 4.2 K.

Findings

Successful observation of Coulomb diamonds at 4.2 K

Effective RF matching with tunable varactors

Analysis of RF leakage effects in nanostructures

Abstract

We demonstrate the measurement of p-channel silicon-on-insulator quantum dots at liquid helium temperatures by using a radio frequency (rf) reflectometry circuit comprising of two independently tunable GaAs varactors. This arrangement allows observing Coulomb diamonds at 4.2\,K under nearly best matching condition and optimal signal-to-noise ratio. We also discuss the rf leakage induced by the presence of the large top gate in MOS nanostructures and its consequence on the efficiency of rf-reflectometry. These results open the way to fast and sensitive readout in multi-gate architectures, including multi-qubit platforms.