Radio-frequency capacitive gate-based sensing

TL;DR

This paper demonstrates a fast, sensitive, and scalable radio-frequency gate-based sensing technique for quantum dots in silicon, achieving charge sensitivities comparable to state-of-the-art methods.

Contribution

It introduces a novel dispersive sensing approach using lumped-element resonators coupled to quantum dots, optimizing design for enhanced sensitivity and speed.

Findings

Achieved charge sensitivities of 7.7 μe/√Hz at 330 MHz and 1.3 μe/√Hz at 616 MHz.

Resonators with loaded Q-factors between 400 and 800.

Gate-based sensing performance matches the best RF single-electron transistor sensitivities.

Abstract

Developing fast, accurate and scalable techniques for quantum state readout is an active area in semiconductor-based quantum computing. Here, we present results on dispersive sensing of silicon corner state quantum dots coupled to lumped-element electrical resonators via the gate. The gate capacitance of the quantum device is configured in parallel with a superconducting spiral inductor resulting in resonators with loaded Q-factors in the 400-800 range. For a resonator operating at 330 MHz, we achieve a charge sensitivity of 7.7 $\mu$e$/\sqrt{\text{Hz}}$ and, when operating at 616 MHz, we get 1.3 $\mu$e$/\sqrt{\text{Hz}}$. We perform a parametric study of the resonator to reveal its optimal operation points and perform a circuit analysis to determine the best resonator design. The results place gate-based sensing at par with the best reported radio-frequency single-electron transistor sensitivities while providing a fast and compact method for quantum state readout.