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Honestly, until recently I thought that we were somewhat closer to creating a quantum computer and quantum computation of real systems. It turned out that while this is more like the calculation of the shape of a spherical horse in a vacuum. Moreover, despite the fact that the shape of such a “horse” is known initially, the output sometimes turns out to be something between a “cube” and a “jellyfish”. And only now, physicists are slowly beginning to be chosen for something that truly resembles reality.

Professor Alexei Ustinov, head of the Superconducting Metamaterials Laboratory at NRT MISiS, enlightened me about the real possibilities of quantum mechanical calculations, with whom we spoke about the publication of an article with his participation in Nature Communcations. It turned out that one cannot correctly introduce energy losses in a quantum system. And they are, and this fact clearly protruding clearly cannot be ignored indefinitely. Moreover, they are always there - any measurement of a quantum system leads to its change and, as a result, energy exchange with the external environment. That is, any quantum system is open. And how can you not take into account the loss?

Nevertheless, by cunning fabrications, physicists came up with several options for how not to take into account energy losses during the interaction of a quantum of light and matter. To begin with, they remembered that almost any substance consists of atoms that interact in some way with each other. Quite often, these very atoms form fairly strong bonds with each other and form molecules. But the last consideration is not so important for us as the fact that new bonds are formed between atoms - molecular ones. And the length of this connection varies with a certain periodicity. Accordingly, a system of two atoms can be mathematically described as a harmonic oscillator. This is the set of harmonic oscillators that represents matter in quantum mechanics.

The next pass with my hands is similar to the fact that my eldest daughter got up periodically when solving problems in geometry, saying: "Let this angle be equal to 30 degrees." Approximately also sounds the assumption "Let the force of the interaction of a quantum of light and matter is negligible." The steeper is only the symbol of faith of modern quantizers - the Schrödinger equation, which in itself is not derived, but postulated. Nevertheless, such mind games allowed to somehow describe the processes occurring in quantum mechanical systems. The key word here, of course, "somehow." This definition also includes the James-Cummings model, which describes the interaction of only one, and then a two-level atom with one oscillator under the conditions rigidly limiting the system.

It would seem, what's the problem? Once there is interaction, it is necessary to take it into account. But even for the “spherical horse in vacuum” described above, this very Schrödinger equation, which, in essence, is trying to describe the structure of the atom, was solved only for the system “one proton - one electron”. Everything else is an approximation. Nevertheless, I want to understand in detail what happens in the same lasers, for example. This is if it says a peaceful quantum. In addition, the lack of understanding of the fundamental properties of quantum systems can lead to a compromise of communication channels based on quantum cryptography methods. And this paranoid argument from the military arsenal.

Although, let's still about peace technologies. The most peaceful quantum process is photosynthesis. Actually, it became the mechanism that quantum physicists tried to understand. Again, while on the simplest model - a two-level atom and one mode. But taking into account the strong interaction of light and matter, which is about 60% of the energy level. As we remember, for cases where the force of interaction between light and matter is large, there are no calculation methods. Therefore, a simulation called a quantum simulation came to the rescue. With the help of superconducting circuits, scientists have created a model where you can see how a strong interaction arises. You can track it due to such oscillations or, scientifically, beat - this is not only when the oscillator oscillates with a certain period, but also when the magnitude (amplitude) of oscillator oscillations begins to oscillate with its period (see the figure below). These are the beats and managed to fix in the experiment.

You may ask, how did it become known that the beats were supposed to appear there? Such simple systems, when a particle can make only one energy transition between levels, can still be calculated on a computer. Something more complicated is almost impossible. Only handles collect the system of qubits, cool them to hundredths of a Kelvin and take measurements. So the basements of NITU "MISIS" continue to periodically turn into the coldest place in Moscow.

Professor Alexei Ustinov, head of the Superconducting Metamaterials Laboratory at NRT MISiS, enlightened me about the real possibilities of quantum mechanical calculations, with whom we spoke about the publication of an article with his participation in Nature Communcations. It turned out that one cannot correctly introduce energy losses in a quantum system. And they are, and this fact clearly protruding clearly cannot be ignored indefinitely. Moreover, they are always there - any measurement of a quantum system leads to its change and, as a result, energy exchange with the external environment. That is, any quantum system is open. And how can you not take into account the loss?

Nevertheless, by cunning fabrications, physicists came up with several options for how not to take into account energy losses during the interaction of a quantum of light and matter. To begin with, they remembered that almost any substance consists of atoms that interact in some way with each other. Quite often, these very atoms form fairly strong bonds with each other and form molecules. But the last consideration is not so important for us as the fact that new bonds are formed between atoms - molecular ones. And the length of this connection varies with a certain periodicity. Accordingly, a system of two atoms can be mathematically described as a harmonic oscillator. This is the set of harmonic oscillators that represents matter in quantum mechanics.

The next pass with my hands is similar to the fact that my eldest daughter got up periodically when solving problems in geometry, saying: "Let this angle be equal to 30 degrees." Approximately also sounds the assumption "Let the force of the interaction of a quantum of light and matter is negligible." The steeper is only the symbol of faith of modern quantizers - the Schrödinger equation, which in itself is not derived, but postulated. Nevertheless, such mind games allowed to somehow describe the processes occurring in quantum mechanical systems. The key word here, of course, "somehow." This definition also includes the James-Cummings model, which describes the interaction of only one, and then a two-level atom with one oscillator under the conditions rigidly limiting the system.

It would seem, what's the problem? Once there is interaction, it is necessary to take it into account. But even for the “spherical horse in vacuum” described above, this very Schrödinger equation, which, in essence, is trying to describe the structure of the atom, was solved only for the system “one proton - one electron”. Everything else is an approximation. Nevertheless, I want to understand in detail what happens in the same lasers, for example. This is if it says a peaceful quantum. In addition, the lack of understanding of the fundamental properties of quantum systems can lead to a compromise of communication channels based on quantum cryptography methods. And this paranoid argument from the military arsenal.

Although, let's still about peace technologies. The most peaceful quantum process is photosynthesis. Actually, it became the mechanism that quantum physicists tried to understand. Again, while on the simplest model - a two-level atom and one mode. But taking into account the strong interaction of light and matter, which is about 60% of the energy level. As we remember, for cases where the force of interaction between light and matter is large, there are no calculation methods. Therefore, a simulation called a quantum simulation came to the rescue. With the help of superconducting circuits, scientists have created a model where you can see how a strong interaction arises. You can track it due to such oscillations or, scientifically, beat - this is not only when the oscillator oscillates with a certain period, but also when the magnitude (amplitude) of oscillator oscillations begins to oscillate with its period (see the figure below). These are the beats and managed to fix in the experiment.

You may ask, how did it become known that the beats were supposed to appear there? Such simple systems, when a particle can make only one energy transition between levels, can still be calculated on a computer. Something more complicated is almost impossible. Only handles collect the system of qubits, cool them to hundredths of a Kelvin and take measurements. So the basements of NITU "MISIS" continue to periodically turn into the coldest place in Moscow.

Source: https://habr.com/ru/post/408739/