Silicon Quantum Computing

Unique high precision, long range qubit read-out sensors

February 24. 2023

Unique high precision, long range qubit read-out sensors

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Sydney, Australia, 24 February 2023 – Australian quantum computing manufacturer, Silicon Quantum Computing (SQC), has achieved another significant result in the race to build a scalable quantum computer.

PhD student Mark Hogg, along with a team of experts from SQC, have engineered a single lead, single crystal integrated sensor that is both compact for high fidelity, and able to accurately measure the state of multiple qubits.

The team used this sensor to successfully readout three qubits with an average fidelity of ~95% and showed that an optimised version could reach the record 99.95% fidelities recently demonstrated by the team with a 3-lead sensor (



“Key to the result is the fact that our sensor is integrated into a single crystal of silicon made of precision placed phosphorus atoms in a planar geometry. By removing all metal and dielectrics our simple, elegant sensor can sense up to 15 qubits compared to only ~3-4 qubits using conventional manufacturing methods”, says SQC Founder and CEO Michelle Simmons.

“If metal gates are required to define the qubit, and then more metal gates to control the quantum state, then the qubit becomes surrounded by metal and dielectric materials. This not only causes charge noise that reduces coherence and scalability of the system but also leads to higher cross talk, where it becomes difficult to read or control one qubit without influencing the neighbouring one.”

“Our results demonstrate that using only phosphorus and silicon atoms in a crystalline environment, we can remove the metal gates and corresponding dielectric material. A major consequence of this is that we achieved a much higher qubit/sensor ratio with a massive impact on the ability to efficiently scale qubits.”

A recent review of qubits across the different platforms appeared in Nature recently entitled ‘Underdog technologies gain ground in quantum-computing race’ ( The review identified that different qubits platforms are catching up the market leaders, superconducting qubits.

Michelle Simmons said, “Step by step we are demonstrating the importance of precision engineering and the choice of the underlying material platform for scaling.”

Congratulations to the team for this wonderful achievement: Mark Hogg, Prasanna Pakkiam, Sam Gorman, Andrey Timofeev, Yousun Chung, Gurpreet kaur Gulati, Matthew House and Michelle Simmons.

A detailed research paper has been published as Editor’s Pick in PRX Quantum on 24 February, 2023, which can be accessed via the link below.


Single-Shot Readout of Multiple Donor Electron Spins with a Gate-Based Sensor