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Issue 12, 2025
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Extracts from the Internet


The first results of JUNO experiment

The JUNO (Jiangmen Underground Neutrino Observatory) collaboration, including Russian researchers from JINR, INR RAS, and MSU, presented the first results of JUNO experiment measurements of parameters responsible for neutrino oscillations [1]. The JUNO detector, constructed in China, registers neutrinos from nuclear reactors. The distance to the group of reactors is 52.5 km, which is optimal to observe the first oscillation maximum. The detector is located under the ground, screening from cosmic radiation, and contains 20 kt of liquid scintillator viewed by the photomultiplier. Owing to unique detector’s possibilities and its thorough calibration, already within the first 59.1 days of observations, the precision of determining two oscillation parameters was 1.6 times higher than the total precision reached in all the preceding experiments. The values sin2θ12 = 0.3092 ± 0.0087 and Δm212 = (7.50 ± 0.12) × 10−5eV2 for the case of direct mass hierarchy was obtained through comparison of the neutrino flux observed in the detector with the known fluxes from the reactors. With increasing statistics, new important results are expected with a possible clarification of ordering (direct or inverse) of mass states of neutrino. [1] Abusleme A et al., arXiv:2511.14593 [hep-ex]

Relation with spin qubits

One of the branches in quantum calculations concerns spin qubits on the basis of impurity atoms in semiconductors. A high quality of the crystal lattice consisting of zero spin atoms facilitates a high time of qubit coherence, up to several seconds. However, a good isolation simultaneously presented a problem of establishing interaction of qubits with each other and with external control systems. T Chang (Bar-Ilan University, Israel) and their co-authors demonstrated a new effective method of interaction with qubit on the basis of bismuth atom in a silicon lattice [2]. Strong magnetic coupling was established through additional superconducting qubits. Using microwave pulses in the resonator, the spin qubit was initialized, and quantum information was transferred from it to the superconducting qubits, that is, the spin qubit in this case represented a quantum memory element. [2] Chang T et al. Nature Communications 16 9832 (2025)

Superconductivity in moire graphene and the Volovik effect

In their experiment, J M Park (Massachusetts Institute of Technology and Princeton University, USA) and their co-authors examined three-layered moire graphene with atomic layers twisted relative to each other at a certain (“magic”) angle, which changes radically the shape of the Fermi surface [3]. Investigation of materials with twisted atomic layers is a new promising area, called “twistronics”. The electron tunneling spectra between layers showed the co-existence of two V-shaped gaps with different energy scales. By different reactions to temperature and magnetic field, one of these gaps was unambiguously identified as a gap with a superconducting-order node parameter. The magnetic-field dependence of the density of states corresponds to the theoretical predictions made by G E Volovik (L D Landau Institute for Theoretical Physics RAS) in 1993 [4]. Thus, a nontraditional type of superconductivity probably takes place in moire graphene, when electron paring is due to their strong interactions and not due to phonons. [3] Park J M et al. Science, îíëŕéí-ďóáëčęŕöč˙ îň 6 íî˙áđ˙ 2025 ă. [4] Volovik G E JETP Lett. 58 469 (1993)

Askaryan radiation in the ice

In 1961, G A Askaryan (P N Lebedev Physical Institute) predicted the Vavilov-Cherenkov radiation generation by an excess of a negative charge in a cascade produced by cosmic rays [5, 6]. The Askaryan effect has already been observed in dielectrics at accelerators, as well as in cosmic-ray showers in the air. The ARA (Askaryan Radio Array) Collaboration reported on the first observation of Askaryan radiation under the ice surface [7]. The experiment aimed at superhigh-energy neutrino detection is being carried out in Antarctic near the South Pole. It includes five independent stations containing vertical and horizontal strings serving as antennas at a depth up to 200 m in ice. 13 radio wave bursts in the near-surface ice layer, which correspond in their spectrum, direction, and shape of signals to the Askaryan radiation from cascade events produced by cosmic rays, were registered for 208 days of observation. [5] Askar’yan G A Sov. Phys. JETP 14 441 (1962) [6] Askar’yan G A Sov. Phys. Usp. 27 896 (1984) [7] Alden N et al., arXiv:2510.21104 [astro-ph.HE]

A possible discovery of population III stars

First stars in the Universe may have been the so-called population III stars formed out of gas with primary chemical composition. Several candidates are known, but no convincing confirmation that these are population III stars has been obtained. One of the candidates - the object LAP1-B at a redshift z ≈ 6.6 - was found in 2025 by J Webb telescope in the region of gravitational lens on the line of sight. As was shown by the new analysis [8], this object satisfies the basic expected characteristics of population III stars. Namely, its spectrum corresponds to an extremely low metallicity and the predicted star mass function, and the total star mass in it makes up several thousand solar masses. This object is most probably a group of population III stars in the halo of dark matter with mass of ≈ 5 × 107M☉. The content of oxygen corresponds to an explosion of one supernova with an ejection of heavy elements. Although LAP1-B is observed at z ≈ 6.6 (the Universe age is 840 mln years), the stars in it must have been formed still earlier. The gravitational lens imaging is expected to give approximately one such object at z ≈ 6.6, and to discover them in earlier epochs is difficult. [8] Visbal E, Hazlett R, Bryan G L, Astrophys. J. Lett. 993 L17 (2025)

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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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