Professor of Aston University (England) Mikhail Sumetsky and research engineer from ITMO University (St. Petersburg National Research University of Information Technologies, Mechanics and Optics) Nikita Toropov have created a practical and inexpensive technology for the production of optical microcavities with record high accuracy. Microresonators can become the basis for the creation of quantum computers, this was reported last Friday, July 22, by the popular science portal "Cherdak" with reference to the press service of ITMO.
The relevance of work in the field of creating quantum computers is due to the fact that a number of very important problems cannot be solved using classical computers, including supercomputers, in a reasonable period of time. We are talking about the problems of quantum physics and chemistry, cryptography, nuclear physics. Scientists predict that quantum computers will become an important part of the distributed computing environment of the future. Building a quantum computer in the form of a real physical object is one of the fundamental problems of physics in the 21st century.
A study by Russian scientists on the production of optical microcavities was published in the Optics Letters journal. “The technology does not require the presence of vacuum installations, is almost completely free from processes that are associated with the treatment of caustic solutions, while being relatively inexpensive. But the most important thing is that this is another step towards improving the quality of data transmission and processing, the creation of quantum computers and ultrasensitive measuring devices,”says a press release from ITMO University.
An optical microcavity is a kind of light trap in the form of a very small, microscopic thickening of an optical fiber. Since photons cannot be stopped, it is necessary to somehow stop their flow in order to encode information. This is exactly what chains of optical microcavities are used for. Thanks to the "whispering gallery" effect, the signal slows down: getting into the resonator, the light wave is reflected from its walls and twisted. At the same time, due to the rounded shape of the resonator, light can be reflected inside it for a long time. Thus, photons move from one resonator to another at a much lower speed.
The trajectory of the light can be adjusted by changing the size and shape of the resonator. Taking into account the size of the microcavities, which is less than a tenth of a millimeter, changes in the parameters of such a device must be extremely precise, since any defect on the surface of the microcavity can introduce chaos into the photon flux. “If the light spins for a long time, it begins to interfere (conflict) with itself,” emphasizes Mikhail Sumetsky. - In the event that an error was made in the production of resonators, confusion begins. From this you can get the main requirement for resonators: the minimum deviation in size."
Microresonators, which were made by scientists from Russia and Great Britain, are made with such high precision that the difference in their dimensions does not exceed 0.17 angstroms. To imagine the scale, we note that this value is approximately 3 times less than the diameter of a hydrogen atom and immediately 100 times less than the error that is allowed in the production of such resonators today. Mikhail Sumetsky created the SNAP method especially for the production of resonators. According to this technology, the laser anneals the fiber, removing the stresses frozen in it. After exposure to a laser beam, the fiber slightly "swells" and a microcavity is obtained. Researchers from Russia and England are going to continue improving the SNAP technology, as well as expanding the range of its possible applications.
Work on microcavities in our country has not stopped for the past several decades. In the village of Skolkovo near Moscow, on Novaya Street, a house number 100 was built. This is a house with mirrored walls, which in their blue can compete with the sky. This is the building of the Skolkovo School of Management. One of the tenants of this unusual house is the Russian Quantum Center (RQC).
Microcavities today are a fairly topical topic in quantum optics. Several groups around the world are continuously studying them. At the same time, initially, optical microcavities were invented in our country at the Moscow State University. The first article about such resonators was published back in 1989. The authors of the article are three physicists: Vladimir Braginsky, Vladimir Ilchenko and Mikhail Gorodetsky. At the same time, Gorodetsky was a student at that time, and his leader Ilchenko later moved to the United States, where he began to work in the NASA laboratory. In contrast, Mikhail Gorodetsky remained at Moscow State University, devoting many years to studying this area. He joined the RCC team relatively recently - in 2014, in the RCC his potential as a scientist can be revealed more fully. For this, the center has all the equipment necessary for experiments, which is simply not available at Moscow State University, as well as a team of specialists. Another argument that Gorodetsky brought in favor of the RCC was the ability to pay decent wages to employees.
Currently, Gorodetsky's team includes several guys who were previously engaged in scientific activities under his leadership at Moscow State University. At the same time, it is no secret to anyone that it is not easy to keep promising young scientists in Russia today - the doors of any laboratories around the world are open to them these days. And the RCC is one of the opportunities to make a brilliant scientific career, as well as receive an adequate salary, without leaving the Russian Federation. Currently, in the laboratory of Mikhail Gorodetsky, research is underway, which, with a favorable development of events, can change the world.
Optical microcavities are the basis of a new technology that can increase the density of data transmission over fiber optic channels. And this is just one of the possible applications of microcavities. Over the past few years, one of the RCC laboratories has learned how to produce microresonators, which are already being purchased abroad. And Russian scientists who previously worked at foreign universities even return to Russia to work in this laboratory.
According to the theory, optical microcavities could be used in telecommunications, where they would help increase the data transmission density over fiber optic cable. Currently, data packets are already transmitted in a different color range, but if the receiver and transmitter are more sensitive, it will be possible to branch one data line into even more frequency channels.
But this is not the only area of their application. Also, using optical microcavities, one can not only measure the light of distant planets, but also determine their composition. They can also make it possible to create miniature detectors of bacteria, viruses or certain substances - chemical sensors and biosensors. Mikhail Gorodetsky outlined such a futuristic picture of the world in which microresonators are already used: “With the help of a compact device based on optical microcavities, it will be possible to determine the composition of air exhaled by a person, which carries information about the state of almost all organs in the human body. That is, the speed and accuracy of diagnostics in medicine can simply increase many times over."
However, so far these are just theories that still need to be tested. There is still a long way to go to ready-made devices based on them. However, according to Mikhail Gorodetsky, according to the approved plan, his laboratory should figure out exactly how to use microresonators in practice in a couple of years. Currently, the most promising areas are telecommunications, as well as the military. Microresonators may indeed be of interest to the Russian military. For example, they can be used in the development and production of radars, as well as stable signal generators.
So far, the mass production of microcavities is not required. But a number of companies in the world have already started producing devices using them, that is, they were really able to commercialize their developments. However, we are still talking only about piece machines designed to solve a narrow range of tasks. For example, the American company OEWaves (which today employs one of the inventors of microresonators, Vladimir Ilchenko), is engaged in the production of superstable microwave generators, as well as excellent lasers. The company's laser, which produces light in a very narrow range (up to 300 Hz) with very low phase and frequency noise, has already won the prestigious PRIZM award. Such an award is practically an Oscar in the field of applied optics, this award is given annually.
In the medical field, the South Korean group of companies Samsung, together with the Russian Quantum Center, is engaged in its own developments in this area. According to the Kommersant publication, these works in 2015 were at the very initial stage, so it is too early and premature to say something about inventions that would have applied applications.
