High-Fidelity Spin-Qubit Sensor Achieved Using Industrial Silicon Manufacturing.

A compact, industrially fabricated sensor utilising a single-electron box within a silicon metal-oxide-semiconductor structure achieves 99.92% readout fidelity in 340µs, comparable to less compact designs. Independent control of electron tunnelling rates optimises sensor performance. A Hidden Markov Model accurately predicts measurement outcomes, enhancing fidelity calculations and enabling faster qubit initialisation within scalable spin-qubit architectures. This demonstrates a pathway to high-performance sensing integrated directly into silicon qubit systems, maintaining qubit connectivity.

The development of scalable quantum computation necessitates both robust qubits and efficient methods for reading their state. A key challenge lies in creating sensors capable of high-fidelity readout without compromising the connectivity required for complex quantum circuits. Researchers at Quantum Motion, alongside colleagues from the University of Cambridge and IMEC, report a compact, high-fidelity dispersive sensor integrated directly within a silicon metal-oxide-semiconductor (MOS) quantum dot architecture. This sensor, a single-electron box, achieves a readout fidelity of 99.92% within 340 microseconds, comparable to existing, less integrated designs.

The work, detailed in their paper “High-fidelity dispersive spin sensing in a tuneable unit cell of silicon MOS quantum dots”, is led by Constance Lainé, Giovanni A. Oakes, Virginia Ciriano-Tejel, Jacob F. Chittock-Wood, Michael A. Fogarty, Sofia M. Patomäki, Ross C. C. Leon, and M. Fernando Gonzalez-Zalba, with contributions from Lorenzo Peri, Stefan Kubicek, David F. Wise, and John J. L. Morton. Their approach utilises established industrial manufacturing processes, potentially easing the path towards larger, more complex quantum processors.

Compact Sensor Achieves High-Fidelity Readout in Silicon Quantum Dot Architecture

Recent research demonstrates a compact, industrially fabricated sensor capable of achieving high-fidelity readout of spin qubits within a silicon quantum dot architecture. The study, utilising metal-oxide-semiconductor (MOS) technology, focuses on a single-electron box (SEB) integrated within a planar MOS quantum dot, fabricated on a 300mm wafer – a process aligned with industrial scalability. This approach addresses a critical need for compact sensors that maintain qubit connectivity as quantum computing systems increase in complexity.

Researchers achieve a readout fidelity of 99.92% within 340 microseconds, and 99% within a significantly faster 20 microseconds. This performance rivals larger, less compact sensors currently employed in silicon spin qubit systems. Crucially, independent gate control over both the SEB and the double-dot tunnel rates optimises sensor performance. The design prioritises maintaining qubit connectivity, a key challenge in scaling quantum processors.

To further refine readout accuracy, the team developed a hidden Markov Model (HMM) to accurately model the two-electron spin dynamics. This HMM enables a more precise calculation of measurement outcomes, directly contributing to the observed high readout fidelity. The model accounts for the complex interplay of spin states, improving the reliability of qubit state determination.

This work presents a viable pathway towards integrating high-fidelity sensors directly within silicon spin-qubit architectures. Combining industrial-grade fabrication, compact design, and advanced modelling techniques facilitates faster readout and more efficient qubit initialisation. The results suggest that this approach offers a promising route to scaling quantum computing systems while preserving essential qubit connectivity and performance metrics.