High-fidelity dispersive spin sensing in a tuneable unit cell of silicon MOS quantum dots

TL;DR

This paper demonstrates a compact, high-fidelity dispersive spin-qubit sensor integrated within silicon MOS quantum dots, achieving rapid and accurate readout suitable for scalable quantum computing architectures.

Contribution

It introduces a novel, industrially manufacturable dispersive spin sensor with high fidelity and fast readout, integrated into a silicon MOS quantum dot platform.

Findings

Achieved 99.92% readout fidelity in 340 microseconds.

Developed a Hidden Markov Model for improved spin state analysis.

Maintained high fidelity while enabling scalable quantum architectures.

Abstract

Metal-oxide-semiconductor (MOS) technology is a promising platform for developing quantum computers based on spin qubits. Scaling this approach will benefit from compact and sensitive sensors that minimize constraints on qubit connectivity while being industrially manufacturable. Here, we demonstrate a compact dispersive spin-qubit sensor, a single-electron box (SEB), within a bilinear unit cell of planar MOS quantum dots (QDs) fabricated using an industrial grade 300 mm wafer process. By independent gate control of the SEB and double-quantum-dot tunnel rates, we optimize the sensor to achieve a readout fidelity of 99.92% in 340us (99% in 20us), fidelity values on a par with the best obtained with less compact sensors. Furthermore, we develop a Hidden Markov Model of the two-electron spin dynamics that enables a more accurate calculation of the measurement outcome and hence readout fidelity. Our results show how high-fidelity sensors can be introduced within silicon spin-qubit architectures while maintaining sufficient qubit connectivity as well as providing faster readout and more efficient initialisation schemes.