Physicists at Delft University of Technology have achieved a stable, long-distance quantum internet connection between two cities separated by 50 kilometers of standard fiber-optic cable.
The experiment, published in Science, demonstrates that quantum networking is ready to move into the real world. The team transmitted quantum-encrypted data between nodes in Delft and The Hague, maintaining the fragile quantum states needed for unhackable communication.
"This is the moment quantum networking leaves the lab," said Professor Ronald Hanson, who leads the quantum internet division at QuTech. "We've shown that the existing fiber infrastructure that carries your Netflix stream can also carry quantum information."
Unlike classical encryption, which relies on mathematical complexity that powerful computers could eventually crack, quantum encryption leverages the laws of physics themselves. Any attempt to intercept a quantum-encrypted message physically disturbs the quantum states, immediately alerting both sender and receiver.
The key breakthrough involved a new type of quantum repeater based on diamond nitrogen-vacancy centers that extends the range of quantum signals without destroying the delicate quantum information they carry.
"The repeater is the bridge," explained Dr. Matteo Pompili. "Without it, quantum networking is a laboratory curiosity. With it, we can build a global quantum internet."
The European Union has committed €1 billion to developing quantum internet infrastructure under its Quantum Flagship program. Several telecom companies are exploring pilot programs to offer quantum-secured connections within the next two to three years.
While a full quantum internet is still a decade away, the Delft experiment proves the foundational technology works at scale. For cybersecurity experts who have long warned about quantum threats to current encryption, this milestone couldn't come soon enough.
