Quantum network QuNET: Protection against hacker attacks

Eavesdropping-proof encryption QuNET With quantum technology against the hackers of the future As of: October 28, 2026 • 4:39 p.m

Quantum computers and AI will probably soon be able to crack digital encryption. In the future, quantum networks such as QuNET will therefore protect communication. The technology works, but not yet perfect.

Bank transfers, health data, power grids and much more are now at risk of attacks from hackers. To date, the protection of data and network access has been based on mathematics: If the encryptions are complex enough, even supercomputers cannot solve them in a reasonable amount of time. But this security is beginning to falter, warns Andreas Reiserer, professor of quantum networks at the Technical University of Munich.

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Laboratories around the world are working on quantum computers that can solve computing tasks many times faster than previous computers. This would allow them to crack any conventional code, says Christoph Marquardt, Professor of Optical Quantum Technologies at the Friedrich-Alexander University Erlangen-Nuremberg (FAU). He is working on a so-called quantum network that should also withstand attacks from quantum computers.

These quantum computers don't exist yet, but that could change soon: "We have estimates from the Federal Office for Information Security that it will be very risky in four years," says Marquardt.

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On October 28, 2026, a quantum network with QuNET was tested in practice. Data encrypted using quantum technology was sent from Berlin via Thuringia to Bavaria. QuNET is being developed on behalf of the Federal Ministry of Research. Institutes of the Max Planck Society, the Fraunhofer Society, the German Aerospace Center and FAU are involved.

It consists of smaller quantum networks in Berlin, Thuringia and Bavaria. These were connected together to demonstrate that this is possible.

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QuNET's encryption technology is based on principles of quantum mechanics. Light pulses (photons) are transmitted via conventional fiber optic cables. These photons are set into specific vibrations. From this, the sender and receiver can generate a common key.

If someone tries to listen in and observes the state of the photons, it changes. This is noticed by the sender and receiver and they can cancel and restart the data transfer.

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The QuNET initiative warns on its website: Hackers are already storing confidential data in order to decrypt it using future methods, such as quantum computers, once they become available. A quantum network like QuNET offers the advantage that its quantum keys cannot be copied, says Andreas Reiserer.

But the transmission of quantum information with photons has its pitfalls. The quantum states of photons are fragile and light particles can be lost, according to the two scientists.

It is impressive how cleanly glass fibers can be produced these days, says Reiserer. Nevertheless, they would absorb the photons over the course of the route: "After a few hundred kilometers, nothing gets through and the quantum-encrypted communication comes to a standstill."

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Andreas Reiserer is therefore involved in the development of quantum repeaters. These are amplifiers that amplify the quantum information on the go. Similar to what a WLAN repeater does in the home radio network. But there are technical problems that have not yet been solved, says Reiserer.

If light particles are lost on the way over glass fibers, then you have to send out a lot of them. This so-called multiplexing is very difficult to implement in quantum systems. In addition, it is also difficult to produce large numbers of individual light particles. But he is still confident that “it could work out one day.”

At QuNET, however, so-called trusted nodes are set up. These are intermediate stations in which the quantum key is decrypted and converted into a classic, digital key. Then it is encrypted again with quantum physics and sent to the next stage. This means that data can also be transferred over a route from Berlin to Bavaria.

However, Andreas Reiserer criticizes this technology for not achieving end-to-end security. It does not offer the level of security that is ultimately desired for highly sensitive applications.

This topic in the program: tagesschau.de | Quantum network QuNet - how quantum technology protects against eavesdropping | Oct 28, 2026 | 4:09 p.m