Quantum Internet on silicon carbide

Significant electrolyuminescence of color centers in silicon carbide SIC Designer Elena Havina, Press Service of MIFT

Physicists from the Moscow Physics and Technical Institute have found a “forgotten” material that can become the basis for a high-speed quantum Internet. The article published in the leading journal of quantum technologies Nature Partner Journal Quantum Information shows how to increase to more than 1 Gbit/s transmitting information on the channel completely protected by physics laws, and make quantum Internet as fast as classic. Briefly about the study is described in a press release from MIPT.

The whole world leads a race to create quantum computers. The industrial giants of Google, IBM, Microsoft and leading international research centers and universities have long been included in it. It is still unknown when such devices appear, but the world is preparing for their appearance. The fact is that the quantum computer can cause a coup in the field of information security. Confidestial of the information transmitted (personal correspondence, banking information, etc.), is provided today by encryption algorithms, for the hacking of which the classic supercomputer will need years. It is expected that the quantum computer can do this in a split second.

Fortunately, an “antidote” has already been proposed, which allows 100% to protect the transmitted information from quantum computers and generally all kinds of attacks. We are talking about quantum cryptography, the resistance of which is ensured not by the complexity of the decoding, but by the laws of quantum physics. Its principle is based on the impossibility of creating a copy of an unknown quantum state without changing the original. Therefore, the quantum communication line cannot be listened unnoticed by the sender and recipient. The quantum computer here will not help the attackers - even if they intercept the transmitted data, it immediately becomes known about this, and it will not work out of the information imperceptibly.

It is best to transmit information to a distance with the help of light quanta - photons - carrying quantum bits. It is extremely important to use single photons, otherwise the attacker will be able to intercept additional photons and get a copy of the message. The principle of generating single photons is quite simple. An excited quantum system can go into the main state with the emission of exactly one quantum of light. It remains only to find a quantum system suitable for practical use. This is the whole complexity. For example, quantum points work well only at very low temperatures (the order of −200 ℃), and ultramodern two -dimensional materials, such as graphene, simply cannot often radiate photons with electric excitement.

The solution of researchers from MIPT is to use the material already forgotten today in the optoelectronics - silicon carbide. “In 2014, we almost accidentally drew attention to silicon carbide and immediately praised its potential,” says Dmitry Fedyanin, senior researcher at the nanooptics and plasmonics laboratory. However, according to him, for the first time, a single -photograph electrolyminescence in this semiconductor managed to get a group of scientists from Australia in 2015.

Oddly enough, it was from silicon carbide that the whole modern optoelectronics began much nor less: it was first observed in it electrolyminescence (glow when passing electric current), in the 1920s, the first LEDs in the world were demonstrated on its basis, and in the 1970s they were produced on an industrial scale in the USSR. However, in the 1980s, silicon carbide was completely replaced from optoelectronics with light semiconductors and is almost forgotten, so today it is better known as very hard and heat-resistant material from which electrical elements, body armor and brake pads of Porsche, Lamborghini and Ferrari supercars are made.

Dmitry Fedyanin and colleagues from the laboratory of nanooptics and plasmonics of the Center of Photonics and two -dimensional materials of the MIPT in their work studied the physics of single -photograph electro -luminescence of coloring centers in silicon carbide and developed a theory that explains and accurately reproduces experimental results. Color centers are point defects of a crystal lattice with an optical transition in the spectrum area where the infectious crystal is transparent. It is they who play a key role in a single -photon electrolyminescence. Using the developed theory, the researchers showed how to improve the carbide-cream single-photon LED to increase the radiation rate of photons to several billion per second. This is what is required for the implementation of quantum cryptography protocols at a speed of about 1 Gb/s. Two other authors of the study, Igor Khramtsov and Andrei Vishovaya, pay attention to the fact that, most likely, in the future there are other materials that are approaching silicon carbides in terms of brightness of single -photon radiation, but, unlike silicon carbide, devices from them will not be able to be industrially manufactured in the same technological process as most modern microdrows. Due to its compatibility with the CMOP process, single -photograph sources based on silicon carbide are almost inaccessible to the materials competing with it and can solve the problem of low throughput of quantum communication lines.