Quantum physics offers a completely new way to protect information. Why is it needed, is it now impossible to lay a secure communication channel? Of course you can. But quantum computers have already been created, and the moment they become ubiquitous, modern encryption algorithms will be useless, since these powerful computers will be able to crack them in a split second. Quantum communication allows you to encrypt information using photons - elementary particles.
Such computers, having gained access to the quantum channel, one way or another will change the real state of photons. And trying to get information will corrupt it. The speed of information transfer is, of course, lower than with other currently existing channels, for example, with telephone communication. But quantum communication provides a much greater level of secrecy. This, of course, is a very big plus. Especially in today's world where cybercrime is on the rise every day.
Quantum communication for dummies
Once the pigeon mail was supplanted by the telegraph, in turn, the telegraph was supplanted by the radio. Of course, today it has not disappeared, but other modern technologies have appeared. Just ten years ago, the Internet was not as widespread as it is today, and it was quite difficult to get access to it - you had to go to Internet clubs, buy very expensive cards, etc. Today, we don’t live an hour without the Internet, and we look forward to 5G.
But the next new communication standard will not solve the problems that are now facing the organization of data exchange using the Internet, receiving data from satellites from settlements on other planets, etc. All this data must be securely protected. And this can be organized using the so-called quantum entanglement.
What is a quantum bond? For "dummies" this phenomenon is explained as a connection of different quantum characteristics. It is preserved even when the particles are separated from each other by a large distance. Encrypted and transmitted using quantum entanglement, the key will not provide any valuable information to crackers who try to intercept it. All they will get is other numbers, as the state of the system, with external intervention, will be changed.
But it was not possible to create a worldwide data transmission system, because after a few tens of kilometers the signal faded. The satellite, launched in 2016, will help implement a quantum key transfer scheme over distances of more than 7,000 km.
First successful attempts to use the new connection
The very first quantum cryptography protocol was obtained in 1984d. Today, this technology is successfully used in the banking sector. Well-known companies offer cryptosystems they have created.
The quantum communication line is carried out on a standard fiber optic cable. In Russia, the first secure channel was laid between Gazprombank branches in Novye Cheryomushki and on Korovy Val. The total length is 30.6 km, errors occur during key transmission, but their percentage is minimal - only 5%.
China launches quantum communications satellite
The world's first such satellite was launched in China. The Long March-2D rocket was launched on August 16, 2016 from the Jiu Quan launch site. A satellite weighing 600 kg will fly for 2 years in a sun-synchronous orbit, 310 miles (or 500 km) high as part of the "Quantum Experiments on a Cosmic Scale" program. The period of revolution of the device around the Earth is one and a half hours.
The quantum communications satellite is called Micius, or "Mo-Tzu", after a philosopher who lived in the 5th century AD. and, as is commonly believed, the first to conduct optical experiments. Scientists are going to study the mechanism of quantum entanglement and conduct quantum teleportation between a satellite and a laboratory in Tibet.
The latter transmits the quantum state of the particle to a given distance. To implement this process, a pair of entangled (in other words, linked) particles located at a distance from each other is needed. According to quantum physics, they are able to capture information about the state of a partner, even when they are far from each other. That is, you can provideimpact on a particle that is in deep space, affecting its partner, who is nearby, in the laboratory.
The satellite will create two entangled photons and send them to Earth. If the experience is successful, it will mark the beginning of a new era. Dozens of such satellites could not only provide the ubiquity of the quantum internet, but also quantum communication in space for future settlements on Mars and the Moon.
Why do we need such satellites
But why even need a quantum communication satellite? Aren't conventional satellites already in existence sufficient? The fact is that these satellites will not replace the usual ones. The principle of quantum communication is to encode and protect existing conventional data transmission channels. With its help, for example, security was already provided during the parliamentary elections in 2007 in Switzerland.
The Battelle Memorial Institute, a non-profit research organization, exchanges information between chapters in the US (Ohio) and Ireland (Dublin) using quantum entanglement. Its principle is based on the behavior of photons - elementary particles of light. With their help, information is encoded and sent to the addressee. Theoretically, even the most careful attempt at interference will leave a mark. The quantum key will change immediately, and an attempted hacker will end up with a meaningless character set. Therefore, all data that will be transmitted through these communication channels cannot be intercepted or copied.
Satellitewill help scientists test key distribution between ground stations and the satellite itself.
Quantum communication in China will be implemented thanks to fiber optic cables with a total length of 2 thousand km and uniting 4 cities from Shanghai to Beijing. Series of photons cannot be transmitted indefinitely, and the greater the distance between stations, the greater the chance that information will be corrupted.
After a certain distance, the signal fades, and scientists need a way to update the signal every 100 km in order to maintain the correct transmission of information. In cables, this is achieved through proven nodes, where the key is analyzed, copied by new photons, and moves on.
A bit of history
In 1984, Brassard J. of the University of Montreal and Bennet C. of IBM suggested that photons could be used in cryptography to obtain a secure fundamental channel. They proposed a simple scheme for quantum redistribution of encryption keys, which was called BB84.
This scheme uses a quantum channel through which information is transmitted between two users in the form of polarized quantum states. A hacker eavesdropping on them might try to measure these photons, but he can't do it, as mentioned above, without distorting them. In 1989, at the IBM Research Center, Brassard and Bennet created the world's first working quantum cryptographic system.
What does a quantum-opticalcryptographic system (KOKS)
The main technical characteristics of COKS (error rate, data transfer rate, etc.) are determined by the parameters of the channel-forming elements that form, transmit and measure quantum states. Usually COKS consists of receiving and transmitting parts, which are connected by a transmission channel.
Radiation sources are divided into 3 classes:
- lasers;
- microlasers;
- light emitting diodes.
For the transmission of optical signals, fiber-optic LEDs are used as a medium, combined in cables of various designs.
The nature of quantum communication secrecy
Going from signals in which transmitted information is encoded by pulses with thousands of photons to signals in which, on average, there are less than one per pulse, quantum laws come into play. It is the use of these laws with classical cryptography that achieves secrecy.
The Heisenberg Uncertainty Principle is used in quantum cryptographic devices and thanks to it, any attempts to change the quantum system make changes to it, and the formation resulting from such a measurement is determined by the receiving party as false.
Is quantum cryptography 100% hack-proof?
Theoretically yes, but technical solutions are not entirely reliable. Attackers began to use a laser beam, with which they blind quantum detectors, after which they stop responding toquantum properties of photons. Sometimes multi-photon sources are used, and hackers may be able to skip one of them and measure identical ones.
