CEA and Quobly Report Simultaneous, Microsecond Qubit-Readout Solution With 10x Power-Use Reduction

Using Quobly’s Strategy to Build Qubits With FD-SOI Technology, Readout Architecture ‘Provides a Path to Low Power and Scalable Quantum’ ICs

SAN FRANCSCO – Feb. 18, 2025 – CEA-Leti, in its collaboration with Quobly, CEA-List and CEA-Irig, reported today it has developed a unique solution using FD-SOI CMOS technology that provides simultaneous microsecond readouts of tens of quantum devices, while reducing the readout power consumption by 10x and footprint by 2x. Combined with Quobly’s strategy to build qubits out of FD-SOI technology, this readout architecture provides a path to low power and scalable quantum integrated circuits.

In a paper presented at ISSCC 2025, “An 18.5μW/qubit Cryo-CMOS Charge-Readout IC Demonstrating QAM Multiplexing for Spin Qubits”, the innovation is to propose a readout circuit based on a capacitive-feedback transimpedance amplifier (CTIA) that achieves an 18.5μW/qubit power consumption, which is a significant tenfold reduction compared to existing, similar circuits at half the footprint per qubit.

With this circuit, CEA-Leti demonstrated a 4- and 16-point quadrature-amplitude modulation (QAM), that increases the possible number of multiplexed devices by directly using the quantum devices as a modulator.

A capacitive-feedback transimpedance amplifier converts the current coming from the quantum devices into an output voltage. Its gain can be set by adjusting the ratio of the values of the two capacitances of its feedback loop.

The novel system presented minimizes power consumption with a multiplexing strategy that permits measurement of several qubits with one amplifier. This paves the way toward developing the readout of thousands of silicon qubits with a limited number of wires and without the need of bulky inductors, circumventing both the wiring bottleneck and the readout scaling-up limitation of actual cryogenic electronics.

“The silicon qubit is a promising candidate for large-scale, fault-tolerant quantum computing due to its small footprint, higher operating temperature and possible compatibility with industrial CMOS processes,” said Quentin Schmidt, lead author of the paper. “But the need for a simultaneous microsecond readout of thousands of devices is especially challenging in terms of both power consumption and size.”

“This is the first time that as-complex-a-modulation scheme as QAM has been used to address the simultaneous readout of several qubits,” explained Franck Badets, research director of the institute’s Silicon Components Department. “The associated improvements in power efficiency and footprint per qubit for a single amplifier, compared to frequency division multiplexing access state-of-the-art, demonstrated with OOK modulations, open bright perspectives for larger-scale qubit arrays.”

"Quobly’s goal is to fabricate large-scale quantum computers based on silicon. This paper demonstrates key progress toward a scalable readout of the qubits and is a major advance in its roadmap," explained Tristan Meunier, chief scientist at Quobly, a pioneer in the development of a fault-tolerant quantum computer based on silicon qubits. "Our process, which leverages established FD-SOI technology to benefit from the expertise of the semiconductor industry, is already paying off: This work demonstrates the co-integration of classical electronic functions at low temperature to simultaneously read and control multiple qubits on chip with record low consumption and compact design. Quobly’s partnership with STMicroelectronics, to produce commercial quantum processor units (QPUs) at scale, builds on the ground-breaking work done with CEA-Leti."

This highly collaborative effort reported at ISSCC was made possible by the unique expertise based in Grenoble. CEA-List offers invaluable guidance to ensure compatibility with future quantum software stacks, while CEA-IRIG provides a one-of-a-kind cryogenic experimental platform. Through their special partnership with Quobly, all divisions of CEA are positioned to pioneer significant breakthroughs in silicon qubit systems.

About CEA-Leti (France)

CEA-Leti, a technology research institute at CEA, is a global leader in miniaturization technologies enabling smart, energy-efficient and secure solutions for industry. Founded in 1967, CEA-Leti pioneers micro-& nanotechnologies, tailoring differentiating applicative solutions for global companies, SMEs and startups. CEA-Leti tackles critical challenges in healthcare, energy and digital migration. From sensors to data processing and computing solutions, CEA-Leti’s multidisciplinary teams deliver solid expertise, leveraging world-class pre-industrialization facilities. With a staff of more than 2,000 talents, a portfolio of 3,200 patents, 11,000 sq. meters of cleanroom space and a clear IP policy, the institute is based in Grenoble, France, and has offices in Silicon Valley, Brussels and Tokyo. CEA-Leti has launched 76 startups and is a member of the Carnot Institutes network. Follow us on www.leti-cea.com and @CEA_Leti.

Technological expertise

CEA has a key role in transferring scientific knowledge and innovation from research to industry. This high-level technological research is carried out in particular in electronic and integrated systems, from microscale to nanoscale. It has a wide range of industrial applications in the fields of transport, health, safety and telecommunications, contributing to the creation of high-quality and competitive products.

For more information: www.cea.fr/english

About Quobly

Quobly is harnessing the power of semiconductor innovation to unlock the full potential of quantum technologies. By using the same tried-and-tested methods for fabricating transistors, Quobly is pioneering the development of fault-tolerant quantum computers. This breakthrough approach paves the way for scalable, cost-effective quantum processors. Based in Grenoble, the startup is the result of 15 years of collaborative research between the CEA-Leti and CNRS. Founded in 2022, Quobly today counts a team of over 70 people. In 2023, Quobly made headlines with a seed round of 19 million euros, and in 2024 Quobly announced its collaboration with STMicroelectronics to bring reproducibility, yield, and quality to silicon qubits using FD-SOI semiconductor processes.

Visit https://quobly.io/

About CEA-List

CEA-List CEA-List, specialized in smart digital systems, is one of the specialized technological research institutes of CEA (French Alternative Energies and Atomic Energy Commission). It combines scientific excellen in high-tech fields like artificial intelligence, software design, simulation, cybersecurity, and qua computing with tech transfer to companies and specialized on digital systems. In particular, CEA-List actively contributes to the dissemination of model-based engineering approaches in the fields of robotics, automotive, railways, energy, industry of the future, and healthcare, providi tailored solutions for each of these domains and contributing to the formation of international ecosystems. CEA-List is a strategic member of the Eclipse Foundation, where it has been leading the Papyrus project for over 10 years, supporting international standards UML and SysML.

About CEA-Irig the Interdisciplinary Research Institute of Grenoble (France)

CEA-Irig is a fundamental research institute at CEA that employs 1,100 people. Based in Grenoble, France, the institute covers a wide range of theoretical and experimental research in the fields of physics, chemistry, biology and instrumentation. The teams associated with other French research institutes are involved in 4 major thematic pillars: Biology-Health, Physics-Digital, Energy-Environment and Cryotechnologies. All of its R&D is supported by the exceptional research platforms with instruments at the cutting edge. Some of these are National Research Infrastructures serving the French and European communities, with the French light and neutron lines at ESRF and ILL (F-CRG: French Collaborative Research Group). The CEA-Irig is a "knowledge factory" and a place of innovation to support societal transitions (digital, health and energy).

Visit https://irig.cea.fr/drf/irig/english/Pages/Welcome.aspx