On Monday 22 November, researchers from the Technical University of Denmark and the University of Copenhagen successfully demonstrated an absolutely secure connection – in this case a video connection – between DTU and the Niels Bohr Institute.

It wasn’t just any connection though. It was a so-called quantum encrypted connection in the form of a single-photon-based quantum encryption link between DTU in Lyngby and NBI on Blegdamsvej in Copenhagen.

What is quantum encryption?

Quantum encryption is an encryption technology that uses quantum mechanical properties to encrypt communication – specifically, it is based on the exchange of so-called quantum keys between sender and receiver protected by quantum technology. Quantum key distribution systems can never be broken, even by the most powerful, future quantum computers.

The core of such a system is the sharing of the key using so-called single photons (light “particles”).

Any attempt to eavesdrop on the system would require intercepting a photon – which is indivisible – i.e. that any attempt at eavesdropping will be detected.

Source: University of Copenhagen


Prevents hostile eavesdropping

The encryption technologies used today can be broken with a quantum computer. But it is precisely also quantum computers that can solve the very same problem. Quantum encryption is expected to become the foundation for future cyber security and the protection of digital communication.

This is because any attempt to eavesdrop on a quantum-encrypted connection will be revealed. Therefore, quantum encryption can provably resist all attacks, explains Peter Lodahl, who is a professor at the Niels Bohr Institute and head of the project and the basic research center Hybrid Quantum Networks (Hy-Q).

Photo: Ola J. Joensen, NBI

20 years of Danish basic research

Denmark is at the forefront globally when it comes to research in quantum mechanics. 20 years of basic research, which has been supported by Denmark’s Basic Research Foundation through the centers Silicon Photonics for Optical Communication (SPOC) and Hybrid Quantum Networks (Hy-Q,), has led to the implementation of the tests under the project FIRE-Q, which is supported by the Innovation Fund.

With yesterday’s successful demonstration, we are one step closer to a quantum internet, where quantum computers can be linked together and become even more powerful. Now the academic and industrial partners in the project are ready to commercialize the technologies.


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