Supported by the Quantum Flagship, the ONCHIPS consortium is laying the foundations for a new type of quantum hardware with advanced materials that have never been combined before.
The team hope to make quantum computers more practical for real-world applications and enable them to solve challenging problems – unlocking new possibilities for science, industry, and everyday users.
The ONCHIPS team is turning to Germanium-Silicon (GeSi) – a material whose ability to emit light efficiently was only discovered in 2020.
Quantum computers are set to be exceptionally powerful tools but researchers seeking to scale them up to the size face significant hurdles, particularly when it comes to their fundamental building blocks, or ‘qubits.’
“One major issue of scalability is that qubits are often limited in their ability to interact with one another,” explained project coordinator Professor Floris Zwanenburg, full professor at the University of Twente’s MESA+ Institute for Nanotechnology. “As the number of qubits increases, effective communication between them becomes more complex.”
Germanium-Silicon (GeSi), however, presents a viable solution to overcome these bottlenecks.
“We are combining spin qubits for computation and photonics for communication on a GeSi platform that is compatible with traditional CMOS manufacturing, which could be a total game-changer for scaling quantum computers. By combining spin qubits (electrons) with photonic communication (light), the chip bridges the gap between processing quantum information and transmitting it over long distances. This will significantly help us solve a major bottleneck in quantum scalability,” Professor Zwanenburg said.
While GeSi has been used and studied for decades as a material system in applications like transistors in semiconductor physics, it has never been implemented in quantum computing. Scientists have worked with cubic GeSi for years and even built qubits using it, but this special, hexagonal light-emitting version of the material has never found its way into a real quantum computer – until now.
“Materials like GeSi can have different arrangements of their atoms under different conditions,” said Professor Zwanenburg. “These arrangements dictate whether the material conducts electricity, emits light, or interacts with quantum particles. When we look at the atomic structure of ‘hexagonal GeSi’, the atoms do not appear in the usual “cubic” pattern. Instead, they have a six-sided, hexagonal, honeycomb-like arrangement.
“In this ‘hexagonal phase’, this special structure makes the material better at giving off light. The atomic structure means it is suitable for quantum applications and photonics, where controlling light is crucial for communication, computation, and storage.
The ONCHIPS team are making their quantum chips cheaper, easier to make, and ready to roll off the production line. To fit all the components onto a single piece of material, the team uses a ‘monolithic integration’ technique, in effect making the entire chip all at once.
“ONCHIPS takes a unique and interdisciplinary approach: we are integrating everything onto a single chip to reduce the size and complexity of the system, making it easier to scale up. All the components, such as the qubits, communication pathways, and supporting electronics, are integrated into a single piece of material.”
By employing the techniques used today to develop computer chips or microchips with Complementary Metal–Oxide–Semiconductor (or ‘CMOS’) technology, the new quantum chips will be set up and ready for mass production and will help to bring Europe’s quantum ecosystem together with its established semiconductor industry.
The success of the ONCHIPS project could reduce reliance on imported advanced chips for quantum technologies and contribute to Europe’s goal of technological sovereignty. The consortium hopes to bolster the EU’s ability to produce advanced quantum chips domestically and position the continent as a pioneer in scalable quantum systems.
ONCHIPS brings together a consortium of leading European organisations. The partners include Universiteit Twente in the Netherlands, which coordinates the project, along with Technische Universiteit Eindhoven (Netherlands), Technische Universität München (Germany), Centre National de la Recherche Scientifique (CNRS) (France), Universität Konstanz (Germany), Budapesti Műszaki és Gazdaságtudományi Egyetem (Hungary), and the Dutch company Single Quantum BV.
