Imagine a regular computer chip, but instead of transistors, it uses special atoms — rare earth ions — frozen inside crystals. These atoms can do something transistors can't: they remember their state while also talking to each other using light, even at telecom wavelengths. The SQUARE team figured out how to control these atoms one by one, turning them into the building blocks for a quantum computer that could eventually be connected into a network, much like today's internet links data centers. Think of it as going from a single calculator to a connected supercomputer, but at the quantum level.
Quantum computers promise to solve problems that classical computers cannot — from drug discovery to logistics optimization to breaking current encryption. But building reliable, scalable quantum hardware remains one of the biggest engineering challenges of our time. Most approaches struggle with qubit stability, limited connectivity between processors, and inability to use existing telecom infrastructure for networking.
The project developed individually addressable rare earth ion qubits as building blocks for quantum processors, engineered tunable fiber cavities into deployable photonic components (delivered to first external test customers), and created protocols for scalable quantum architecture with spin-photon quantum state mapping at telecom wavelengths. A total of 27 deliverables were completed across the project.
If you are a telecom company exploring quantum-secure communication — this project developed photonic interfaces using rare earth ions that couple to telecom-wavelength photons, meaning quantum processor nodes could plug into existing fiber-optic infrastructure. The consortium delivered fiber cavities to external test customers, showing early hardware readiness for integration testing.
If you are a cybersecurity company worried about quantum threats to current encryption — this project built quantum processor nodes where multiple qubits handle storage, gates, and spin-photon mapping. These are the core components needed for quantum key distribution hardware. With 8 partners across 5 countries and 27 deliverables completed, there is a substantial knowledge base to license or co-develop from.
If you are a photonics or quantum hardware company looking for a scalable qubit platform — this project engineered tunable fiber cavities into deployable technologies and delivered them to first external test customers. Rare earth ions offer strong dipolar interactions for fast quantum gates, a competitive advantage over other qubit approaches. The 2 industry partners in the consortium signal commercial interest already exists.
The project does not publish licensing fees. Since this was a publicly funded RIA project, some results may be available through collaboration agreements with the coordinator at Karlsruhe Institute of Technology. SciTransfer can help you explore licensing terms.
The project explicitly targeted scalable quantum hardware as its main goal. However, the current stage is focused on demonstrating basic elements of a quantum processor node, not mass production. The delivery of fiber cavities to external test customers is a first step toward manufacturability.
IP from RIA projects is typically owned by the consortium partners who generated it, in this case spread across 8 partners in 5 countries. Karlsruhe Institute of Technology (DE) as coordinator would be the first point of contact for IP discussions.
Rare earth ions offer a unique combination: large number of qubits per register, fast quantum gates via dipolar interactions, and native coupling to telecom-wavelength photons. Based on available project data, this positions the technology well for networked quantum computing, where optical connectivity is essential.
The project completed 27 deliverables in total, including 1 demo deliverable: tunable fiber cavities delivered to first external test customers. The project also developed schemes and protocols for scalable quantum architecture.
Quantum computing hardware currently faces export control considerations in the EU, particularly for dual-use technology. Based on available project data, the project focused on fundamental building blocks rather than end-user products, so regulatory exposure at this stage is limited.
The consortium includes 4 universities and 2 research organizations with deep expertise in rare earth ion physics and quantum photonics. Karlsruhe Institute of Technology leads the project and maintains the project website for ongoing information.
The SQUARE consortium brings together 8 partners from 5 countries (Germany, Denmark, Spain, France, Sweden), led by Karlsruhe Institute of Technology. The mix is research-heavy: 4 universities and 2 research organizations do the science, while 2 industry partners (25% of the consortium) bridge toward commercialization. No SMEs are involved, which suggests the technology is still too early for small companies to absorb, but the presence of industry partners and the delivery of fiber cavities to external test customers signal that commercial pathways are being explored. For a business looking to enter this space, the consortium offers strong academic depth but would need additional engineering and manufacturing partners to move toward product.
Karlsruhe Institute of Technology (KIT), Germany — reach out via their quantum technology research division
Want an introduction to the SQUARE team? SciTransfer can connect you with the right researchers and help you evaluate licensing or collaboration options.
