Quantum breakthrough enables ultra-secure data transmission in existing networks

A breakthrough in quantum communication has allowed secure data transmission within existing data centres. Researchers successfully combined shortwave quantum key distribution (QKD) with standard telecom infrastructure, achieving a secure-key rate of 12 kb/s. The system operated alongside 50 classical data channels, demonstrating compatibility with current networks without needing dedicated fiber lines.

Quantum key distribution has long promised unbreakable encryption, but its adoption faced hurdles due to reliance on specialized fiber setups. A team led by Mariana F. Ramos, Costin Luchian, and Michael Hentschel tackled this by integrating shortwave QKD into conventional data centre architectures. Tests over installed fiber loops—including a 270-metre office loop and a 692-metre rooftop loop—showed stable performance, with an average raw-key rate of 19.2 kb/s and a peak-to-peak quantum bit error rate fluctuation of just 5.7%.

The team addressed key technical challenges, such as speckle-selective loss and differential mode delay, which can depolarise signals and degrade QKD performance. Few-mode propagation in short-reach systems also posed difficulties, but optimisations like mode filtering at the final optical connection reduced the quantum bit error rate by roughly 3%. Further refinements to launch conditions for QKD modes enhanced overall stability. Experiments confirmed the system’s reliability, maintaining high security and efficiency even alongside active data traffic. This approach eliminates the need for separate fiber infrastructure, cutting costs and simplifying deployment in real-world telecom environments.

The findings open a path for practical, large-scale quantum-secured networks. By operating within existing data centre setups, the technology reduces barriers to adoption while maintaining strong encryption standards. Future implementations could see wider use of QKD in telecommunications, improving security without major infrastructure changes.