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| Issue 4, 2024 |
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Extracts from the Internet | ||
Reactor antineutrino anomaly1 February 2023Since 2011, the problem called the reactor antineutrino anomaly has been known: the measured spectrum of antineutrinos emitted from nuclear reactors in the energy range of 3-4 MeV is lower by 6 % than the spectrum obtained in theoretical calculations. This discrepancy, confirmed in several independent experiments cannot be explained within the Standard Model with allowance for oscillations between the three ordinary types of neutrinos. It was hypothesized that the decrease in the number of antineutrinos is due to their oscillations into the fourth type of neutrinos – sterile neutrinos with masses of ≈1 eV. The new spectrum measurements and the tests of sterile neutrino hypothesis were performed in the STEREO experiment at the Institut Laue-Langevin (Grenoble, France) [1]. Six detectors based on liquid gadolinium-containing scintillator were arranged in a row at distances of 9 to 11 m from a nuclear reactor. The difference in the spectra measured by them would make it possible to reveal the effect of oscillations. 105 antineutrinos have been detected for three years. The spectrum of reactor antineutrinos from 235U decays measured by the STEREO collaboration is currently the most precise. The obtained data confirm the presence of antineutrino anomaly: the difference between the measured spectrum and the theoretical one makes up 5.5 ± 2.1 %. At the same time, the STEREO experiment has not revealed the oscillation effect, and thereby the reactor antineutrino anomaly is most likely not related to sterile neutrino. The recent results of the BEST experiment carried out in the Baksan neutrino observatory of INR RAS [2] confirmed the presence of gallium anomaly pointing to the existence of a sterile neutrino. But the STEREO detector sensitivity in the range of gallium anomaly energy is low, and the STEREO data cannot be directly compared with the BEST results. For neutrino oscillations, see [3-5]. [1] Almazan H et al. Nature 613 257 (2023) [2] Barinov V V et al. Physical Review C 105 065502 (2022) [3] Kudenko Yu G Phys. Usp. 61 739 (2018); UFN 188 821 (2018) [4] Simkovic F Phys. Usp. 64 1238 (2021); UFN 191 1307 (2021) [5] Kolupaeva L D et al. Phys. Usp., accepted Spatial separation of wave and corpuscular photon’s properties1 February 2023In quantum mechanics, the concept of “the quantum Cheshire cat” exists, which consists in separating the object’s physical properties from itself. Such an effect has already been realized to separate the spin of a particle from the particle itself in experiments with neutrons and photons. In their experiment, J.-K Li (University of Science and Technology of China) and their co-authors spatially separated the wave and corpuscular properties of single photons for the first time [6]. This new version of separation was proposed in the theoretical paper by P. Chowdhury and their co-authors in 2021. The wave property of a particle (“cat”) passed along one arm of Mach-Zehnder interferometer, and its corpuscular property (“smile”) passed along the second arm. Superposition of wave-particle states was made preliminarily, and preselection and postselection of states were performed. A scheme called evolution in imaginary time was applied for weak quantum measurements. The results of measurements agree well with the theoretical description. One of the next goals is a triple separation (“quantum Cheshire supercat”) into the particle itself, its wave property, and its corpuscular property. [6] Li J-K et al. Light: Science & Applications 12 18 (2023) Interaction-free quantum measurement1 February 2023The problem of measurement remains one of the fundamental questions of quantum mechanics [7-9]. The measurement can also be interaction-free, when, e.g., the presence of a photon is registered without its absorption. The interaction-free measurement has already been demonstrated for different systems. S. Dogra, J.J. McCord, and G.S. Paraoanu (Aalto University, Finland) proposed and experimentally implemented a new type of interaction-free quantum measurement [10]. A three-level transmon qubit was used. By the population of its zeroth and first levels, one can judge the presence or absence of a microwave pulse with frequency resonant for transition from the first level to the second. Given this, the qubit excitation with transition to the second level is not required, while the mere fact of the presence of the second resonant level is sufficient. [7] Kadomtsev B B Phys. Usp. 37 425 (1994); UFN 164 449 (1994) [8] Pronskikh V S Phys. Usp. 63 192 (2020); UFN 190 211 (2020) [9] Belinsky A V Phys. Usp. 63 1256 (2020); UFN 190 1335 (2020) [10] Dogra S, McCord J J, and Paraoanu G S Nature Communications 13 7528 (2022) Quantum energy teleportation?1 February 2023In previous experiments on quantum teleportation of particle states, information was actually teleported. However, in 2008, M. Hotta (Tohoku University, Japan) proposed a conception of energy teleportation. His idea is based on the fact that when measuring the state of a certain local part of a quantum entangled system, the measuring device transfers energy to the system, and owing to entanglement this energy can be released in another distant part of the system. K. Ikeda (Stony Brook University) reported the first experimental implementation of the above-described effect [11] by performing quantum energy teleportation between superconducting qubits with an IBM quantum processor. The results of the experiment are exactly consistent with M. Hott’s theory. As with ordinary quantum teleportation, quantum energy teleportation requires local operations and information transfer through a classical channel. For quantum technologies, see [12-15]. [11] Ikeda K, arXiv:2301.02666 [quant-ph] [12] Arbekov I M, Molotkov S N Phys. Usp. 64 617 (2021); UFN 191 651 (2021) [13] Klimov V V Phys. Usp. 64 990 (2021); UFN 191 1044 (2021) [14] Sukachev D D Phys. Usp. 64 1021 (2021); UFN 191 1077 (2021) [15] Vladimirova Yu V, Zadkov V N Phys. Usp. 65 245 (2022); UFN 192 267 (2022) Baryonic clouds and galactic halo rotation1 February 2023The extended galactic halos consisting largely of dark matter contain also several percent of gas and dust carried out to the halo by the stellar wind and gas streams. The presence of dust is also noticed in the intergalactic space [16]. F. De Paolis and their co-authors assumed that the gas-dust medium in the halo may partially be in the form of cold virialized clouds, and their motion due to the general halo rotation can be released from the Doppler shift of the relic radiation scattered by clouds. Galaxies begin rotating on the stage of their formation through their interaction with the environment. The observation of several galaxies by WMAP and Planck telescopes actually revealed shifts in the spectra, corresponding to halo rotation. In the new study of N. Tahir and their co-authors [17], different versions of composition, structure, and distribution of cold baryon clouds in the halo were considered for several galaxies. The results were compared with the data of the Planck space telescope. The presence of cold baryon clouds in rotating galactic halos explains well the observations, although other interpretations are not excluded. [16] Yershov V et al. Mon. Not. R. Astron. Soc. 492 5052 (2020) [17] Tahir N et al. Symmetry 15 160 (2023) |
The Extracts from the Internet is a section of Uspekhi Fizicheskih Nauk (Physics Uspekhi) — the monthly rewiew journal of the current state of the most topical problems in physics and in associated fields. The presented News is devoted to the fundamental discoveries of physics and astrophysics. Permanent editor is Yu.N. Eroshenko. It is compiled from a multitude of Internet sources. | |
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