4.2\xa0K sensitivity-tunable radio frequency reflectometry of a physically defined p-channel silicon quantum dot

Sinan Bugu,Shigenori Murakami,Tetsuo Kodera,Yongxun Liu,Kimihiko Kato,Thierry Ferrus,Takahiro Mori,Shimpei Nishiyama

doi:10.1038/s41598-021-99560-x

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.

Highlights

We demonstrate the measurement of p-channel silicon-on-insulator quantum dots at liquid helium temperatures by using a radio frequency reflectometry circuit comprising of two independently tunable GaAs varactors
In the low-signal regime, when the changes in the ratio of resistance to capacitance are small, the signal-to-noise ratio (SNR) depends on the coupling c oefficient[33,34] that becomes maximum at perfect matching condition
We purposely use p-channel Metal-Oxide-Semiconductor (PMOS) devices to demonstrate such an rf leakage effect induced by the top gate and discuss the ability to perform rf reflectometry

Summary

Introduction

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. In quantum dot architectures, such a circuit can be integrated either at the sensor, for example a single electron transistor or a quantum point contact close to the device to measure[16,17,18,19], or directly at one of the control gate of the device itself[20,21,22,23,24,25,26,27] Both techniques have proven to be reliable with bandwidths in excess of 10 MHz and are suited to quantum dots where the low-stray parasitic capacitance, generally lower than 1 pF, allows the use of moderate inductance sizes and values to obtain a high resonance frequency while retaining good impedance matching. A high-quality resonator with low parasitic capacitance was combined with varactors to improve significantly the charge sensitivity in the range of 55 mK to 1.5 K34 Such a limitation in the use of rf reflectometry can be severe in certains architectures, like in p-channel silicon devices where mobilities are lower compared to the ones found in n-type devices. We purposely use p-channel Metal-Oxide-Semiconductor (PMOS) devices to demonstrate such an rf leakage effect induced by the top gate and discuss the ability to perform rf reflectometry

Methods

Results

Conclusion