A bold new project aims to build quantum light sources from erbium in silicon—creating the backbone for tomorrow’s ultra-secure, high-speed quantum networks.
Key Points at a Glance
- Project EQUAL integrates quantum light sources with quantum memories for the first time
- Uses erbium ions in silicon nanocavities to emit single photons in the telecom C-band
- Backed by €5.3M from Innovation Fund Denmark and involves multiple European institutions
- Breakthrough nanophotonics make this integration possible
Quantum communication and computing promise to transform our digital world—but to get there, we need new kinds of light. Not just any light, but light that carries quantum information in single photons and works seamlessly with our existing fiber-optic networks. Enter the EQUAL project: a newly launched Danish-German collaboration aiming to make scalable quantum light sources a reality.
Backed by €5.3 million from Innovation Fund Denmark, the five-year initiative is developing erbium-based silicon quantum emitters that can interact with quantum memories—devices that store quantum states for synchronization and processing. This integration is critical for enabling the next-generation quantum internet, which would allow quantum computers to talk to each other over vast distances with absolute security.
“One of the toughest goals is to integrate quantum light sources with quantum memories,” says project coordinator Søren Stobbe from the Technical University of Denmark (DTU). “This seemed unrealistic just a few years ago, but now we see a path forward.”
At the heart of this innovation is erbium—a rare-earth element already used in traditional fiber optics for signal amplification. It emits photons in the telecom C-band, exactly where global fiber networks already operate. But erbium doesn’t naturally interact strongly with light. Thanks to advanced nanophotonic chips developed at DTU, that barrier is being broken. These chips boost the interaction between light and erbium ions embedded in silicon structures, enabling controlled single-photon emission.
Researchers at Helmholtz-Zentrum Dresden-Rossendorf (HZDR) are helping bring this vision to life. Using focused ion beam techniques, they implant individual erbium atoms into tiny silicon nanocavities with nanometer precision. These precisely engineered structures are key to controlling the emission and storage of quantum light. According to Dr. Yonder Berencén of HZDR, “This research lays the groundwork for building quantum devices that can be integrated into today’s silicon-based technology.”
Beyond the lab, the project brings together expertise from Humboldt University in Berlin on quantum networks, Beamfox Technologies on nanotech fabrication, and Lizard Photonics on low-power photonics. It’s a collective push to make scalable, energy-efficient, and integrable quantum systems viable within the next decade.
By combining materials science, optics, quantum physics, and advanced fabrication, EQUAL could be a game-changer. Its success would mean secure quantum communication through existing infrastructure, and scalable quantum computing connections—all starting from a single, perfectly placed erbium atom.
Source: HZDR Press Release
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