Breakthrough in Quantum Fiber Networks Enables Secure Multi-User Communication
Scientists have developed a new way to build secure quantum fiber communication networks that connect multiple users at once. The method uses light to encode information, making it harder to intercept and faster to transmit. Researchers say this could be a major step toward a fully connected quantum internet.
The team created a network based on continuous-variable quantum key distribution (CVQKD), a technique known for its speed and compatibility with existing systems. Instead of relying on single photons, it encodes data in the amplitude and phase of light. This allows higher key rates and easier integration with current fiber-optic infrastructure.
At the heart of the system is an optical frequency comb, which generates multiple entangled light states at once. These states are produced using spontaneous four-wave mixing (SFWM) inside a compact photonic chip. The researchers also used an entanglement-in-the-middle architecture, where a central node distributes entangled pairs to all users, ensuring secure connections without direct links between them.
Tests and simulations showed the network works well over short distances, as long as noise and signal loss are kept low. The approach, called ‘a model for continuous-variable quantum key distribution in a network using linked frequency combinations’, was developed by research groups specialising in quantum optics and communication. Teams from TU Delft, several European and Asian universities, and national quantum labs contributed to the work.
This breakthrough demonstrates how scalable quantum computing networks could be built using existing technology. The method allows multiple users to share encrypted keys efficiently, paving the way for secure data transfer and quantum cryptography. Future work will focus on extending the range and improving stability for real-world applications.
