Chinese scientists have successfully tested a highly secure quantum data link between two cities. The two cities are located at a distance of 511 km from each other. However, there was a traditional relay system in between. In the future, however, it could become a secure quantum network.
This process is performed thanks to a feature of quantum mechanics, namely quantum entanglement. In it, two particles affect each other even when they are at a distance, ie when the condition of one particle is known, it becomes easier to detect the properties of the other particle.
In the experiment, when two particles of light, a photon, are passed through quantum entanglement, the process of quantum encryption takes place. This way, highly confidential and secure information can be sent over long distances. Several months ago, Chinese experts exchanged simple quantum information with two drones.
In this way, safe ‘keys’ can be formed at the quantum level. Now scientists at the University of Science and Technology have experimented with long-distance quantum communication using a cable. There are several steps involved, but they do not read the data or reveal the secrets.
Laser photons were sent on both sides of the fiber optic wire. The states (phases) of these particles were random, that is, their waves were sloping and moving. When a pair of photons in the middle path met with particles of the same phase, the system immediately alerted the sender and recipient of the conventional data link.
Since it is known from each side what is being sent and what is being received or whether one particle matches another, experts can exchange quantum keys with this process. It can now encrypt data even if it is sent over a traditional network. In the meantime, none of the data can be identified.
Recently in Cambridge, Toshiba Europe also exchanged quantum information with the same technology at a distance of 600 km, but all the equipment was kept in one place. However, the Chinese team actually exchanged quantum information 511 km away between the two cities. Jinan and Qingdao have been selected for this while the main receiver was installed in Mazan city.
However, experts at the Cambridge Experience have praised the Chinese effort, saying that in the meantime, the exchange of information hundreds of kilometers away, despite temperature and other external factors, is a significant achievement.