Optical computers

2023

Development of a nanodevice used as a transistor for an optical computer

Physicists of ITMO and the Academic University named after Zh.I. Alferov have developed a device that can be used as a transistor for an optical computer. The development allows without the use of electrical conductors to create an electric field in a nanostructure. Scientists were able not only to theoretically describe this process, but also to experimentally demonstrate it in a nanoantenne. The results of the study are published in the journal Light: Science & Applications. This was reported on September 21, 2023 in ITMO. Read more here.

The discovered nanoparticle effect will allow the creation of nanoantennes for quantum and optical computers

An international team of physicists has shown that a certain shape allows nanoparticles to be in an electromagnetic sense larger than their geometric dimensions. This was announced on August 14, 2023 by representatives of the Moscow Institute of Physics and Technology. The discovered effect will help in the creation of biological sensors, materials for solar panels and elements of optical and quantum computers. The results of the study are published in the journal Nature Communications.

In dielectric photonics studying how light interacts with nanoparticles from various nonconductive structures, there was a theoretical limit to nanoparticle light scattering.

"When radiation laser hits the nanoparticle, it scatters electromagnetic energy as a set of well-defined spherical waves -- multipoles. Each multipole is a scattering channel through which some of the scattered energy flows. In the scientific community, it was widely recognized that each such channel cannot carry power more than a certain limit, "says Adria Canos Valero, first author of the study, a researcher. ITMO

A scientific team led by Alexander Shalin of MIPT investigated how to maximize scattering from nanoparticle clusters. In the course of the work, scientists found that in most situations, scattering is greater than expected. At first, the researchers thought it was a numerical error. But then they quickly realized that the physical principle was at the heart.

It turned out that the pre-existing scattering limit is well defined for ideal scenarios: when light is scattered on a spherical particle or on an infinitely long nanowire. In general, scattering produces multiple multipole channels that can interfere by increasing or decreasing the power they carry. Scientists have wondered how much more it is possible to go beyond the scattering limit.

The key to answering this question lay in the physics of related states in the continuum. Namely, in a special form of interfering resonances known as the Friedrich-Wyntgen resonance mechanism. Previously, quasi-states with highly suppressed scattering have been described. Destructive interference occurs in them, when waves from multipoles fold "in antiphase," suppressing each other. The researchers realized that in their case, resonances with increased scattering follow the same physics. Only interference is constructive: when the waves add up "in phase," amplifying each other.

The scientists built the model and calculated the shape of the nanoparticles, at which it is possible to "break" the limit and achieve super-scattering. The theorists' recipe experimenters then produced suitable ceramic particles and tested the predictions using microwave spectroscopy.

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Nature Communications

"This is, above all, a fundamental effect. Some colleagues, to whom I briefly talked about our results, did not believe: they said that this could not be the case. Now they can read the article and make sure that they can, "says Alexander Shalin, research leader, leading researcher at the MIPT Laboratory of Controlled Optical Structures.

In addition to the fundamental importance, super-scattering has potential practical applications. Since this effect is very sensitive, it will be possible to develop biosensors and materials for solar panels, as well as optical nanoantennes for quantum and optical computers.

"One potential practical application that illustrates the effect found well is to create some shield against electromagnetic forces and radiation. The picture shows that the light goes around the particle, and the shadow is much larger than the particle itself. It turns out that behind it you can "hide" something larger than the particle itself, "explains Alexander Shalin.

The study was supported by the Priority 2030 Federal Academic Leadership Program.

Russian physicists have discovered material for creating compact light computers

In early June 2023, physicists from Russia and Europe revealed that a two-dimensional form of boron nitride could be used to create ultraviolet waveguides and various other nanophoton devices.

According to the press service of the Moscow Institute of Physics and Technology (MIPT), researchers have long believed that all solid materials in nature have only a three-dimensional shape. But by the middle of the century, mathematicians and theoretical physicists had proved the opposite: "flat" atomic structures can exist in principle and that they can be stable.

Physicists in the Russian Federation have discovered material for creating compact light computers

Researcher at MIPT Georgy Dolgoprudny said that ultraviolet nanophotonics is just emerging. It is necessary to reduce the wavelength of light in order to reduce the size of photon devices. Scientists have demonstrated that boron nitride is perfectly suitable for this due to the fact that it has a very high optical anisotropy. Dolgoprudny added that scientists from MIPT and colleagues from the Institute of Physics of the Russian Academy of Sciences came to this conclusion in the course of experiments with hexagonal boron nitride, one of the forms of two-dimensional materials with unusual physical and optical properties. Dolgoprudny said that they managed to find a transition bridge that would allow them to move from electronics to photonics. For June 2023, scientists continue their work to show this superiority of light compared to the electron in a real quantum integrated circuit.

According to MIPT, scientists were able to measure the optical properties of hexagonal boron nitride for the first time. The researchers found that this material has a record high refractive index - 2.75 when interacting with ultraviolet radiation. According to the researchers, hexagonal boron nitride can be used to create photonic elements of the order of tens of nanometers, and this is comparable to the size of transistors in integrated circuits of computer circuits.

The first research material called graphene was discovered in 2004. Later, many other flat materials were discovered in physics and chemistry, which were not inferior in their properties to this material: sulfur and molybdenum compounds, hexagonal boron nitride and other substances simple in structure.^[1]

2021: Scientists create structure to develop compact optical computer parts

A group of scientists from the National ITMO University University of Colombia and the University of Siena have developed a structure that is special in its properties. With its help, it is possible to control electromagnetic surface waves much more efficiently - localized waves that propagate along various surfaces. This opens up other possibilities in creating compact optical devices for transmission and processing. data ITMO University announced this on August 19, 2021.

The phenomenon of surface waves has been studied by scientists for a long time. A visual example of this phenomenon is surface waves on water, which look like diverging circles from an abandoned stone. Electromagnetic surface waves in optics are a promising way to transmit localized light in a plane, which is important for the development of miniature optical and optoelectronic data transmission and processing systems - antennas and amplifiers, optical circuits and transmitters, screens and sensors, as well as elements of an optical computer. However, there are a number of problems that prevent this method from being implemented into real devices.

Since surface waves diverge in circles, at long distances from the source they lose almost all energy. Then the scientists learned to transmit an optical signal from point to point in channeling mode, when the wave propagates in a narrow beam along a given direction. But using this mode, it is quite difficult to switch between different directions of light propagation. And, in addition, in the channeling mode, no one has previously been able to control the polarization of waves transmitted in the plane. Light polarization is actually an optical bit, that is, polarization control allows you to "sew" information into the light, "explained Oleg Ermakov, a researcher at the New Physics and Technology Department of ITMO.

ITMO scientists managed to solve all these problems using a special type of two-dimensional structure - a self-reinforcing metasurface consisting of two periodically repeating elements: a dipole antenna and a slot in a metal layer of the same shape.

Our structure obeys the Babine principle, due to which metasurface elements pass into themselves during inversion, revealing special properties. It is surprising that following this fundamental and long-known law of optics, we managed to implement a fairly simple structure and immediately solve many problems over which scientists fought for years, "added Oleg Ermakov.

So far, the proposed structure can only work in the microwave, terahertz and far infrared bands. That is, the resulting metasurface can be reduced only by a thousand times, and, for example, not by a million. At the same time, scientists are confident that this technology can be implemented in the visible range using dielectric structures, which they continue to work on.

The study was supported by the Russian Science Foundation, the Russian Foundation for Basic Research and the BASIS Foundation for the Development of Theoretical Physics and Mathematics.

See also

• Optical transistors
• Optical reflectometer
• Reflectogram
• Halide perovskites