A group of researchers in Beijing has established a new world record in direct communication protected by quantum encryption. This team has managed to establish them in this way at a distance of 102.2 kilometerssignificantly exceeding the distance reached in the previous record, which was 18 kilometers, as reflected in the publication of the study on achieving the record in Nature.
Of course, the maximum data transfer speed achieved in this communication with quantum encryption is not high at all. Quite the contrary, since it has only been possible to reach 0.54 bits per second. Despite the slowness, yes, it was possible to make encrypted phone calls and send text messages at a distance of 30 kilometers.
The achievement represents an important advance in secure communications through quantum computing with a view to its application in certain scenarios that require that the communications established be proof against attacks and hackers, such as those related to national security or those that have to establish between governments and official institutions. With its establishment across quantum lines, any eavesdropping attempts that try to go unnoticed will be detected the moment they occur.
This type of communication uses the principle of interleaving to secure networks. Quantum physics says that entangled particles are related, so if you change the property of one of them by measuring it, the other will instantly change too, making hacking impossible. Theoretically, particles remain bound even when they are several light-years apart, so systems of this type should work over large distances.
The researchers who have broken this record are the same ones who established the previous one, which is why they have been working on improving this type of secure communication for some time now. To achieve this, they have developed a design of a new physical system, which also has a new protocol. The team further simplified the system by removing one of the subsystems used by the previous model, the one that set the previous record. Specific, got rid of an active compensation subsystem, which was quite complex. In doing so, they also made the system have an extremely low quantum bit error rate, as well as long-term stability against environmental noise.
Thanks to all this, the system can withstand so-called channel losses much better, which makes it impossible to decode encrypted messages. In addition, it allowed the researchers to extend the fiber from the 28.3 kilometers with which they were working in principle to the record distance achieved, which, as we mentioned, is 102.2 kilometers.
