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| Issue 9, 2026 |
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Extracts from the Internet | ||
Search for millicharged particles1 August 2026According to one hypothesis, dark-matter particles may carry electric charges several orders of magnitude smaller than the electron charge. Despite the electromagnetic interactions of millicharged particles (MCP) and their possible accumulation near the Earth, the MCP model has not yet been stringently constrained. Experiments on MCP direct detection and accelerator-production, as well as constraints on the properties of supernova SN 1987A, still leave open a broad range of MCP parameters. Thus, these particles, which are absent from the Standard Model, therefore remain viable dark-matter candidates. A Berlin (Fermi National Accelerator Laboratory, USA) and their co-authors demonstrated that MCPs could, in principle, be detected in Cavendish-type experiments that measure the electric field inside a metal cavity [1]. Unlike ordinary atomic ions, MCPs could penetrate such cavities and produce a volume electric charge there. Using historical data concerning such experiments of this type conducted with an alternating electric field, A Berlin et al. obtained new constraints on MCPs, extending the excluded parameter region for masses from MeV to GeV. Moreover, the authors of [1] proposed combining a Cavendish experiment with a Van de Graaff generator. Under the action of field of several million volts, the MCP concentration must increase by ≈ 12 orders of magnitude. This would make it possible to detect MCPs produced by cosmic rays in the atmosphere independently of a dark-matter model. Such an experiment could, moreover, set stronger constraints than those expected from planned accelerator experiments. [1] Berlin A et al. Phys. Rev. D 114 015016 (2026) Emergence of coherence in a Bose – Einstein condensate1 August 2026M Koster (RPTU University Kaiserslautern-Landau, Germany) and their coauthors have, for the first time, followed in detail how coherence develops in a magnon system during Bose – Einstein condensation (BEC) in a ferrimagnetic yttrium iron garnet film, Y3Fe5O12 in a magnetic field [2]. A parametric pumping and detection of the magnetic response (a free-precession signal) were both performed with a microstrip antenna. During pumping, the magnon concentration increased, and the system underwent a spontaneous transition to a coherent BEC state. The phase evolved linearly with time, demonstrating coherence; the initial phase value occurred randomly from shot to shot and was correlated with neither the pump phase nor the phase of an external reference oscillator. This method opens new possibilities for controlling coherent magnon flows in spintronic devices. [2] Koster M et al. Nat. Phys., online publication of July 13, 2026 Quantum entanglement through a nonlocal reservoir1 August 2026Quantum entanglement of systems, one of the fundamental concepts of quantum mechanics, is usually generated either by creating entangled particle pairs at a common source or by transferring particles. In 2004, however, B Kraus and J I Cirac proposed a different way of entanglement: spatially separated particles could be entangled through their interaction with a nonlocal reservoir containing photons in squeezed states. A Andrés-Juanes (Institute of Science and Technology Austria, ISTA) and their coauthors were the first to realize this method for entanglement distribution experimentally [3]. A Josephson parametric converter generated an entangled state of propagating microwave fields, which drove two spatially separated superconducting qubits into a stationary entangled state. Neither active control nor postselection was required and entanglement occurred autonomously. Measurement of entanglement by quantum tomography showed full agreement with the theoretical model. [3] Andres-Juanes A et al. Phys. Rev. X 16 031005 (2026) The Casimir effect in a nonlinear regime1 August 2026The Casimir effect is of fundamental interest in searches for new interactions and may also have practical applications in micromechanics [4]. When the Casimir force is measured between superconductors, the problem of accurate positioning the surfaces can be solved by observing nonlinear oscillations associated with the anharmonic Casimir potential. M H J de Jong (Aalto University, Finland) and their co-authors used this approach to carry out new, high-precision measurements of a Casimir force [5]. They investigated the oscillations of a superconducting aluminum membrane integrated into a microwave resonator at a temperature of 1010 mK. Because of the nonlinearity, the resonance oscillation frequency decreases with increasing amplitude. A detailed analysis excluded any appreciable contribution from other nonlinear effects that had hampered earlier experiments. Owing to small transverse scales, the Casimir force was substantial: its effect was equivalent to a pressure of approximately 1/10 atm. In the future, a similar technique can be used to investigate quantum levels of an oscillating membrane. [4] Mostepanenko V M, Trunov N N Sov. Phys. Usp. 31 965 (1988) [5] de Jong M H J et al. Nature Communications 122 153601 (2025) Determining the order of neutrino mass states from cosmological observations1 August 2026Neutrino-oscillation experiments have not yet determined the neutrino mass hierarchy, although they have now closely approached this goal. At the same time, independent information about the ordering can also be obtained from cosmological data. Light neutrinos undergo free streaming, which makes galaxy clustering sensitive to the sum of the mass of three states: ∑ mν=m1+m2+m3. The data of the review of galaxies DESI DR2 and Planck telescope give ∑ mν < 0,0642 eV. Simultaneously, observations of neutrino oscillations give the following restrictions from below ∑ mν ≈ 0,059 0.059 eV for direct hierarchy and ∑ mν ≈ 0,099 eV to inverse one. Thus, cosmological data are already difficult to reconcile with inverted ordering but admit direct hierarchy. This conclusion depends considerably on the method of reliability analysis and Bayesian models. In paper [6], a detailed methodology for such an analysis was developed and it was found that the Bayes factor in favor of the direct hierarchy compared to the inverse one is K > 460 in a fairly conservative case, although the result weakens to K > 40 in models with a variable equation of state of dark energy. Therefore, the direct mass ordering is much more probable from the point of view of cosmology. Determination of the character of hierarchy may significantly constrain the possible mechanisms of neutrino mass origin. [6] Jimenez R et al., arXiv:2606.18987 [astro-ph.CO] |
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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