Key point: Quantum key distribution functions on standard fiber optic networks with parallel data traffic up to 64 terabits per second over 60 kilometers – dark fibers are no longer required.
A consortium led by German company KEEQuant has demonstrated for the first time that quantum key distribution (QKD) and high-performance data transmission can run simultaneously over the same standard fiber optic cable. This significantly lowers the entry barrier for post-quantum cryptography in existing telecommunications networks.
The consortium comprising KEEQuant (Germany), CESNET (Czech Republic), EXATEL and PCSS (Poland) demonstrated in joint tests that quantum key distribution and classical data traffic can coexist without any problems on the same G.652.D standard fiber optic cable. Until now, it had been assumed that dedicated dark fiber connections were required – a significant cost factor for network expansion and operations.
In the test environment, several scenarios were validated: 64 terabits per second over 60 kilometers (80 channels of 800 gigabits per second each), 32 terabits per second over 65 kilometers (40 channels of 800 gigabits per second each), and 32 terabits per second over 75 kilometers (80 channels of 400 gigabits per second each). In parallel with the data traffic, KEEQuant’s QKD system generated cryptographic keys that were managed via a key management system. A video was transmitted end-to-end encrypted as practical proof.
For CTOs and infrastructure managers, this delivers a clear economic advantage: quantum-safe encryption can now be implemented in existing transport networks without expensive new fiber optic deployments being necessary. This significantly reduces capex and complexity for upgrading to post-quantum cryptography. For network operators and critical infrastructure operators, this means they can meet their security requirements without fundamental infrastructure overhauls.
The tests took place in a production-realistic DWDM environment with fully utilized infrastructure. KEEQuant was responsible for the QKD and key management systems; EXATEL provided operational requirements; CESNET provided the test environment; and PCSS provided the fiber optic infrastructure. The results indicate that quantum-safe communication has reached the transition phase from research to productive operation.
Source: www.it-daily.net · Published July 2, 2026
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