The international team of scientists announced the firstsimultaneous transmission of an encrypted quantum message that was sent from a space satellite to two ground-based telescopes located at a distance of 1120 kilometers from each other. In such a safe communication channel, scientists were able to connect the cities of Nanshan and Delinha. However, while the data is transmitted rather slowly, it takes about one and a half minutes to send one byte. As the Spanish El Pais writes, despite the fact that quantum phenomena occur on a microscopic scale, they can affect the visible world.
What is a quantum communication channel?
Using the Mo-Tzu satellite of physics from China,Great Britain and Singapore created a quantum channel of communication between the two Chinese cities. It should be noted that one of the main problems in the operation of modern quantum communication systems is that the light gradually “dies” when moving through an optical fiber, therefore, the Mo-Tz satellite (Micius) was used for the repeater:
Using the communication satellite "Mo-Tzu" we managedproduce a quantum key exchange between two ground stations. This was made possible by increasing the transmission efficiency of entangled photons by about four times and achieving a speed of 0.12 bits per second. But using ground-based data transmission systems, the distance between the nodes of quantum networks is only a few hundred kilometers, the authors write in a new work.
Theoretically, the quantum distribution isAn absolutely safe way to exchange secret keys between remote users. The method is based on the fundamental laws of quantum physics: the process of measuring a quantum system changes its state. According to The Conversation, two particles can be intertwined in such a way that what happens to one instantly happens to the other, even if they are separated by billions of kilometers. If someone tries to observe these particles during transmission, their state changes and entanglement is violated. This property allows you to create a communication system, theoretically impossible for hacking, since the fact of observation destroys the message.
If everything that happens seems somewhatsurprising, you will be interested to know that for many years China, Europe and the United States have been working on the development of quantum communication networks to send official messages or create cybersecurity systems at strategic sites. Earlier in the laboratory, researchers demonstrated experimental key distribution using 421 km of optical fiber.
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In a study published in the journal Nature,scientists describe in detail the transmission of a secret key written in pairs of entangled photons - particles of light using the Mo-Tzu satellite, which rotates at a distance of 500 kilometers from the Earth. Using a satellite is crucial because transmitting these messages using optical fiber loses a lot of photons, so repeaters are required every 100 or 150 kilometers. Moreover, the repeater with all its mechanical components can be hacked.
World of quantum information
It is noteworthy that in a published studyscientists demonstrate the protection of their communications system from various types of attacks and show that it is safe. Its speed and efficiency are 100 million times higher than that of terrestrial optical fiber. The work lays the foundation for a global quantum communications network, emphasize the authors of the study. And indeed, so far no one has succeeded in transmitting a quantum message at such a great distance.
For many years, the Celestial authorities have been investing largeamounts of money in new technologies of quantum communication both in space and on earth. In a previous experiment, researchers were able to connect Beijing and Shanghai to a fiber optic network to transmit quantum keys. In addition, the country set several records in the field of communications from space, for example, the transmission of a quantum key in 2017, which made it possible to maintain a teleconference between Vienna and Beijing at a distance of more than 7,000 kilometers, by the way, also using the satellite of the Mo-Tzu satellite.
The difference is that last timethe satellite acted as a safe for storing the key when moving from point A to point B. It is during transmission that the signal becomes vulnerable to espionage. Recall that the concept of quantum communication was invented in Europe, and it was here that the first fundamental experiments in this field were carried out. But since China is betting on the adoption of this technology, this area of research is generously funded. The authors of the study also believe that the success of the last experiment will push Europe to develop its own network, although using its own technologies. Which, I cannot but note, is somewhat strange, since science has no boundaries.
See also: Launched the first in Russia multinode quantum network
Anyway, the next milestone will bethe use of geostationary satellites located at a distance of about 35,000 kilometers from the Earth will increase the distance over which encrypted messages can be transmitted using quantum technology. And what do you think, what will lead us to create a quantum communication system? We will wait for the answer here!