RF Reflectometry for Readout of Charge Transition in a Physically Defined PMOS Silicon Quantum Dot

TL;DR

This paper demonstrates RF reflectometry for charge state readout in a silicon quantum dot by reducing device size and optimizing impedance matching, enabling high-temperature, fast charge and spin state detection.

Contribution

It introduces a new silicon quantum dot device with minimized top gate area and optimized impedance matching for effective RF charge readout at 4.2 K.

Findings

Successful fabrication of a single quantum dot suitable for RF readout

Achieved charge transition detection at 4.2 K using RF reflectometry

Improved impedance matching enhances readout performance

Abstract

We have embedded a physically defined p-channel silicon MOS quantum dot (QD) device into an impedance transformer RC circuit. To decrease the parasitic capacitance and surpass the cutoff frequency of the device which emerges in MOS devices that have a top gate and act as RC low-pass filter, we fabricate a new device to reduce the device's top gate area from 400 $\mbox{$\mu$m}^2$ to 0.09 $\mbox{$\mu$m}^2$. Having a smaller top gate eliminates the cutoff frequency problem preventing the RF signal from reaching QD. We show that we have fabricated a single QD properly, which is essential for RF single-electron transistor technique. We also analyze and improve the impedance matching condition and show that it is possible to perform readout of charge transition at 4.2 K by RF reflectometry, which will get us to fast readout of charge and spin states.