Scientists have recently succeeded in transmitting coherent quantum messages over 254 kilometers of commercial optical fiber. This sets a new world record for quantum communication. The researchers did not use cryogenic systems for this, but instead utilized an existing telecommunications infrastructure in Germany. Are you curious about how this project was set up? In this article, we’ll tell you all about it!
A new speed record for fiber-optic cables
A team of scientists in Germany successfully transmitted quantum messages over 254 kilometers of conventional fiber-optic cables. These cables connect the German cities of Frankfurt, Kehl, and Kirchfeld. This is the first time this has been achieved without the use of expensive cryogenic cooling systems. The system the researchers used for this was developed by Toshiba Europe. During the tests, this system transmitted quantum-encoded messages at a speed of 110 bits per second. Is that fast? Absolutely—it’s actually a record speed for quantum technology.
How does this revolutionary system work?
But how exactly does this newly developed system work? Toshiba based it on a technique known as “Twin Field Quantum Key Distribution.” In this technique, two parties send light pulses to an intermediate point that measures the interference between the two signals. This method effectively doubles the secure transmission distance without requiring physical protection of the central node. This makes expanding urban quantum networks a whole lot easier!
Long distances
The biggest obstacle to quantum communication is maintaining the coherence of quantum states over long distances. This is quite a challenge, as it’s akin to whispering a secret to someone during a violent thunderstorm. Yet these German scientists have succeeded. Thanks to innovative phase stabilization techniques, they managed to maintain coherence over hundreds of kilometers of fiber-optic cables. A successful proof of concept, then, from the scientists. With this, they are paving the way toward an unbreakable “quantum internet.” This means that quantum communication can be integrated via the fiber-optic cables that have already been installed in all our cities. No entirely new networks are needed; we can simply use the existing infrastructure. This would allow the technology to be deployed much more quickly worldwide.