A collaborative effort between Danish and German researchers,including the Helmholtz-Zentrum Dresden-Rossendorf (HZDR),is underway to create innovative quantum light sources. The goal is to develop technology for scalable quantum networks,utilizing the rare-earth element erbium. The EQUAL project (Erbium-based silicon quantum light sources) has received funding from the Innovation Fund Denmark, totaling 40 million Danish crowns (approximately 5.3 million euros), and is scheduled to run for five years, commencing in May 2025.

Quantum technology holds the potential for ultra-secure encryption and the creation of entirely new computer types. These future computers are expected to be interconnected via optical quantum networks.A key challenge is the current lack of suitable quantum light sources,which the EQUAL project aims to address.

According to project coordinator Søren Stobbe, professor at the Technical University of Denmark (DTU), “it is a really difficult task, but we have also set a really strong team. One of the toughest goals is to integrate quantum light sources with quantum memories.This seemed unrealistic just a few years ago,but now we see a path forward.”

The project’s technological approach involves combining nanophotonic chips from DTU with advanced technologies in materials science, nanoelectromechanics, nanolithography, and quantum systems. Existing quantum light sources frequently enough face limitations,either in compatibility with quantum memories or with optical fibers.

Erbium is considered a promising element, but its interaction with light is weak. New nanophotonic technology developed at DTU aims to considerably enhance this interaction. The project also requires advancements in nanophotonics, quantum technology, low-power integrated photonics, and nanofabrication methods.

HZDR will focus on developing new quantum light sources using silicon, a common material in electronics. These light sources will operate at wavelengths compatible with fiber-optic interaction, making them suitable for secure communication and powerful computing. “We intend to use advanced ion beam techniques to implant erbium atoms into tiny silicon structures and study how using ultra-pure silicon can improve their performance. This research will lay the foundation for building quantum devices that can be integrated into today’s technology,” explains Dr. Yonder Berencén, the project’s principal investigator from the Institute of Ion Beam Physics and Materials Research at HZDR.

The EQUAL project also benefits from contributions from Humboldt University in Berlin (quantum networks), Beamfox technologies ApS (nanotechnology), and Lizard Photonics ApS (integrated photonics).

“We intend to use advanced ion beam techniques to implant erbium atoms into tiny silicon structures and study how using ultra-pure silicon can improve their performance.”

Advancing Quantum Technology

The EQUAL project represents a significant step towards realizing the potential of quantum technology.By focusing on the progress of compatible and efficient quantum light sources, the project aims to overcome a key obstacle in the creation of scalable quantum networks.

The Role of erbium and Silicon

The choice of erbium and silicon is strategic. Erbium’s properties make it suitable for quantum applications, while silicon’s prevalence in the electronics industry offers potential for integration and scalability. The project’s success could pave the way for more widespread adoption of quantum technologies.