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Physics, Volume 8, Issue 2 (June 2026) – 21 articles

Cover Story (view full-size image): Precise control over magnetic and dielectric properties is essential for advancing next-generation sensors and memory devices. This study investigates how thermal treatment tunes coercivity and magnetodielectric coupling in nickel-substituted lanthanum ferrite (LaFe0.7Ni0.3O3). By varying the sintering temperature, the authors demonstrate controlled structural distortions of the FeO6 octahedra accompanied by a significant relaxation of internal microstrain. A semi-empirical magnetocrystalline anisotropy model is proposed to explain the evolution of coercivity and the associated multiferroic behavior. These findings highlight the potential of functional ferrites as sustainable alternatives to rare-earth-based magnetic materials for future electronic components. View this paper
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22 pages, 564 KB  
Article
Deep Gas Sources in Deformable Porous–Fractured Media: Volcanic and Tectonic Systems
by Sebastiano Ettore Spoto
Physics 2026, 8(2), 53; https://doi.org/10.3390/physics8020053 - 11 Jun 2026
Cited by 3 | Viewed by 558
Abstract
Deep gas emissions in volcanic and tectonic environments are commonly interpreted as the surface expression of localized deep emitters. This representation is adequate for first-order description, but it is not physically complete. Deep degassing is more appropriately represented as a coupled source–storage–pathway system [...] Read more.
Deep gas emissions in volcanic and tectonic environments are commonly interpreted as the surface expression of localized deep emitters. This representation is adequate for first-order description, but it is not physically complete. Deep degassing is more appropriately represented as a coupled source–storage–pathway system in which volatile generation, compressible accumulation, phase change, hydraulic communication, and permeability evolution are dynamically linked. Starting from phase-wise mass conservation in deformable porous–fractured media, reduced equations for gas migration, pore-pressure diffusion, and thermo-poro-mechanical coupling are derived, showing how the distinction between gas-mass transport and pressure propagation provides a unified framework for volcanic and tectonic degassing. Deep pressure gradients are shown to arise from the competition between volatile supply and pathway leakance, while episodic discharge can occur when permeability evolves under effective stress, sealing, and failure. A minimal analytical source–storage–pathway model is further derived, yielding explicit criteria for valve onset, source charging and discharge times, and the distinction between pressure-led and mass-led responses. The framework is then applied to the published Campi Flegrei carbon dioxide (CO2) diffuse total output record, providing a real-data illustration of slow storage loading and rapid transient discharge. The analysis considers magmatic exsolution, hydrothermal mediation, metamorphic devolatilization, advective–diffusive near-surface filtering, and the inverse problem through which surface fluxes and gas compositions are used to infer deep source properties. The formulation links magmatic degassing, hydrothermal pressurization, tectonic fluid ascent, and fault-valve behavior within a common continuum-physics perspective and identifies the constitutive assumptions that most strongly control interpretation. Full article
(This article belongs to the Section Classical Physics)
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11 pages, 249 KB  
Article
A Minimal Operational Criterion for No-Signaling Assessment and Near-Identity Binary Transmission
by Lorenzo Albanese
Physics 2026, 8(2), 52; https://doi.org/10.3390/physics8020052 - 11 Jun 2026
Viewed by 343
Abstract
Possible violations of the no-signaling constraint in Weinberg-type nonlinear extensions motivate the question of whether entanglement could, under suitable conditions, become a resource for operational signaling. A minimal binary model is introduced in which, in each run, a sender selects a binary input [...] Read more.
Possible violations of the no-signaling constraint in Weinberg-type nonlinear extensions motivate the question of whether entanglement could, under suitable conditions, become a resource for operational signaling. A minimal binary model is introduced in which, in each run, a sender selects a binary input bit and a receiver locally records a binary output bit. Signaling is defined operationally as a dependence of the local output statistics on the remote input and is summarized by a single channel parameter that can be estimated from data. An estimator and a corrected confidence interval are then introduced to assess this dependence quantitatively, while transmission reliability is expressed through the minimum decision error. On this basis, a conservative criterion is formulated, using an upper bound on the error and a threshold fixed in advance, to characterize a near-identity channel regime. Minimal reporting requirements are also proposed to document the conditions under which artifacts and classical leakage may reasonably be excluded. Full article
27 pages, 7899 KB  
Article
Thermal Treatment-Induced Coercivity Modulation in Magnetodielectric LaFe0.7Ni0.3O3
by Ximena Jocelyn Téllez-Tovar, Félix Sánchez-De Jesús, Claudia Alicia Cortés-Escobedo, María Isabel Reyes-Valderrama and Ana María Bolarín-Miró
Physics 2026, 8(2), 51; https://doi.org/10.3390/physics8020051 - 8 Jun 2026
Viewed by 656
Abstract
This study investigates the modulation of coercivity and magnetodielectric coupling in heat-treated, nickel-substituted lanthanum ferrite. LaFe0.7Ni0.3O3 samples were synthesized by high-energy ball milling and sintered at temperatures between 1073 and 1473 K. Chemical composition, crystalline structural evolution, surface [...] Read more.
This study investigates the modulation of coercivity and magnetodielectric coupling in heat-treated, nickel-substituted lanthanum ferrite. LaFe0.7Ni0.3O3 samples were synthesized by high-energy ball milling and sintered at temperatures between 1073 and 1473 K. Chemical composition, crystalline structural evolution, surface morphology, magnetic, dielectric, and electrical properties, as well as magnetodielectric coupling, were analyzed. The XPS spectra revealed the presence of adsorbed oxygen, associated with the high oxygen affinity of the material. This behavior is interpreted as a charge-compensation mechanism, related both to the formation of oxygen vacancies and to the partial oxidation of Fe3+ to Fe4+. XRD and Rietveld refinement confirmed a single-phase orthorhombic Pnma structure, and structural simulations revealed progressive octahedral distortions with increasing temperature, affecting the octahedral tilting and electronic bandwidth. Magnetic characterization revealed that thermal processing modifies the magnetic behavior, inducing weak ferromagnetism and a significant increase in coercivity, correlating with progressive densification, greater domain stability, and reduced microstrain. Impedance measurements revealed magnetodielectric coupling, the Maxwell–Wagner interfacial polarization mechanism, and reduced dielectric losses. These findings demonstrate that the coercivity and magnetodielectric response in cationic nickel-substituted lanthanum ferrite can be tuned through thermal processing. A semi-empirical magnetocrystalline anisotropy model is proposed to explain the coercivity evolution and associated multiferroic behaviors, thus contributing to the study of functional ferrites as sustainable alternatives to rare-earth magnetic materials with potential in sensors and memory devices. Full article
(This article belongs to the Section Applied Physics)
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22 pages, 3084 KB  
Article
Quantum Bianisotropy in Light–Matter Interaction
by Eugene O. Kamenetskii
Physics 2026, 8(2), 50; https://doi.org/10.3390/physics8020050 - 5 Jun 2026
Viewed by 654
Abstract
Quantum bianisotropy and chirality are fundamental concepts in light–matter interaction that describe how materials with broken symmetries respond to electromagnetic fields at the level of macroscopic quantum electrodynamics. In quantum bianisotropy, magnetoelectric (ME) energy plays a critical role in mediating and enhancing light–matter [...] Read more.
Quantum bianisotropy and chirality are fundamental concepts in light–matter interaction that describe how materials with broken symmetries respond to electromagnetic fields at the level of macroscopic quantum electrodynamics. In quantum bianisotropy, magnetoelectric (ME) energy plays a critical role in mediating and enhancing light–matter interactions. This concept is essential for bridging the gap between classical electromagnetics (where bianisotropy often involves field non-locality) and quantum mechanics in metamaterials. The precise manipulation of a quantum emitter’s properties at a subwavelength scale is due to near fields, which effectively function as a tunable environment. In this paper, it is shown that the ME near field, interpreted as a structure combining the effect of bianisotropy/chirality with a quantum atmosphere, is a non-Maxwellian field with space–time symmetry breaking. Quantum ME fields arise from the dynamic modulation and topological coupling of magnetization and electric polarization within ME meta-atoms—specific subwavelength structural elements with magnetic and dielectric subsystems in magnetic insulators, which are assumed to have quantum properties. Full article
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32 pages, 1345 KB  
Article
Finite-Capacity Spacetime and Entropic Contributions to Cosmological Structure Formation
by Florian Neukart, Eike Marx and Valerii Vinokur
Physics 2026, 8(2), 49; https://doi.org/10.3390/physics8020049 - 2 Jun 2026
Viewed by 708
Abstract
We investigatewhether a finite local information capacity of spacetime can account for the gravitational phenomena commonly attributed to cold dark matter. Starting from a covariant effective-field-theory description, we modelcoarse-grained entropy deposition as a dynamical scalar field S(x) whose stress–energy tensor [...] Read more.
We investigatewhether a finite local information capacity of spacetime can account for the gravitational phenomena commonly attributed to cold dark matter. Starting from a covariant effective-field-theory description, we modelcoarse-grained entropy deposition as a dynamical scalar field S(x) whose stress–energy tensor contributes to structure formation. The macroscopic action contains a single dimensionless coupling λ multiplying the canonical kinetic term, ensuring ghost-free dynamics and conservation of the associated stress–energy tensor. In a slow-roll regime, defined by a covariant source term ΓS¨+3HS˙=0, where H is the Hubble parameter and overdot denotes derivative with respect to cosmic time, and |S¨|H|S˙|, the entropy sector behaves as pressureless dust at background and in linear order. Implemented in a modified Cosmic Linear Anisotropy Solving System (CLASS) Boltzmann solver, the entropy component fits Planck satellite 2018 cosmic microwave background (CMB) data, baryon acoustic oscillation (BAO) measurements, and the Pantheon + Type Ia supernova sample for 0.5λ2, while preserving the linear growth factor to within 0.2% over Euclid space telescope scales. To regulate ultraviolet contributions, we introduce a holographically motivated prescription in which gravitationally active entropy deposition is confined to causal two-surfaces, yielding a ρr2 halo envelope with a finite-density core determined by local entropy saturation. Fixing the flux scale A from astrophysical entropy budgets reproduces Milky-Way-mass halos without introducing fine-tuned length scales. Pilot N-body simulations that evolve the entropy field on a staggered grid reproduce the halo mass function down to 1010.5M, mitigate the cusp–core and missing-satellite tensions, and remain consistent with cluster lensing constraints. On linear scales, the model predicts percent-level, scale-dependent deviations in the lensing convergence and matter power spectra, testable by Euclid space telescope, the Roman Space Telescope High Latitude Survey, and the CMB-S4 experiment. Full article
(This article belongs to the Section Astrophysics, Astronomy and Planetology)
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20 pages, 374 KB  
Article
Equation of State Parameters for Fluid of Stringy Extended Objects in Cosmology with Cosmological Constant
by Soon-Tae Hong and Bum-Hoon Lee
Physics 2026, 8(2), 48; https://doi.org/10.3390/physics8020048 - 2 Jun 2026
Viewed by 517
Abstract
We construct the strong energy conditions (SECs) for both massive and massless stringy extended objects in the higher dimensional cosmology (HDC) with cosmological constant Λ. Exploiting these conditions, we find the equation of state (EoS) parameters [...] Read more.
We construct the strong energy conditions (SECs) for both massive and massless stringy extended objects in the higher dimensional cosmology (HDC) with cosmological constant Λ. Exploiting these conditions, we find the equation of state (EoS) parameters w(D4)/D for both the massive and massless stringy extended objects in D (D5) dimensional cosmology. The stringy SECs impose a universal constraint on w that remains valid across both radiation- and matter-dominated eras. We elucidate the relations between the EoS parameter in the HDC with cosmological constant and that of Hawking–Penrose limit for the massive and massless point particles in the four dimensions. We evaluate the EoS parameters in terms of the contributions from the point particle property, cosmological constant, and extended object degrees of freedom, respectively. We also investigate the weak energy condition for the massive and massless stringy extended objects in the HDC, and those for the massive and massless point particles in the four dimensions, respectively. Full article
(This article belongs to the Section Gravitation and Cosmology)
24 pages, 4479 KB  
Article
Inclination-Driven Thin-Film Dynamics: Geometry-Induced Regime Ordering in the (Bo, Pe, Da) Space
by Helena Cristina Vasconcelos, Reşit Özmenteş and Maria Meirelles
Physics 2026, 8(2), 47; https://doi.org/10.3390/physics8020047 - 1 Jun 2026
Viewed by 647
Abstract
We develop a leading-order continuum framework for thin-film hydrodynamics on inclined solid substrates, integrating capillarity, intermolecular forces, gravitational symmetry breaking, confined transport, and stochastic wetting into a single formulation. Starting from lubrication theory with capillary curvature and disjoining-pressure interactions, we obtain a lubrication-scale [...] Read more.
We develop a leading-order continuum framework for thin-film hydrodynamics on inclined solid substrates, integrating capillarity, intermolecular forces, gravitational symmetry breaking, confined transport, and stochastic wetting into a single formulation. Starting from lubrication theory with capillary curvature and disjoining-pressure interactions, we obtain a lubrication-scale thin-film equation that incorporates inclination-driven advection, nanoscale stabilization, and humidity-controlled source–sink fluxes. A dimensionless analysis shows that, within the long-wave lubrication approximation, inclination induces a coordinated leading-order coupling among the Bond (Bo), Péclet (Pe), and Damköhler (Da) numbers. This coupling defines a characteristic inclination-angle-dependent scaling trajectory Γ(θ) in the (Bo, Pe, Da) space: material parameters set the system’s position along this curve, while the geometric constraint organizes the ordering of hydrodynamic, transport, and confinement regimes. We further derive leading-order crossover criteria associated with transport transitions (Pe ≃ 1) and reactive-confinement loss (Da ≃ 1), providing explicit regime boundaries that can be evaluated for representative parameter ranges. A representative parameterization of an ultrathin atmospheric electrolyte film is then used to make these crossovers explicit, yielding illustrative inclination thresholds that depend on the chosen parameter set. Coupling the deterministic structure to a minimal stochastic closure captures intermittent wet–dry dynamics under environmental forcing. In this closure, inclination selectively accelerates the drying pathway through the drainage time (and thus drying rate λdry), while rewetting remains primarily humidity-controlled, to leading order, providing a scaling-based description of wet-state persistence and time-of-wetness versus θ. The resulting framework provides a continuum-scale physical description of confined films under geometric asymmetry, relevant to wetting, interfacial drainage, confined transport, and thin-film systems in which symmetry breaking and coupled interfacial–transport processes coexist. Full article
(This article belongs to the Section Classical Physics)
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14 pages, 1621 KB  
Article
Entropy Redistribution Induced by Substitutional Doping in Bilayer Graphene
by Juan A. Lazzús
Physics 2026, 8(2), 46; https://doi.org/10.3390/physics8020046 - 26 May 2026
Viewed by 373
Abstract
This study investigates the thermodynamic consequences of substitutional doping in bilayer graphene using a minimal tight-binding model in which doping is encoded as a reduction in the intralayer hopping amplitude α in one sheet. The interlayer coupling Δ fixes the low-energy window, while [...] Read more.
This study investigates the thermodynamic consequences of substitutional doping in bilayer graphene using a minimal tight-binding model in which doping is encoded as a reduction in the intralayer hopping amplitude α in one sheet. The interlayer coupling Δ fixes the low-energy window, while 0<α<1 introduces spectral asymmetry without generating new energy scales. The results show that decreasing α redistributes the density of states toward the Fermi level, producing an enhancement of the low-energy density of states within the hybridized inner branches. As a consequence, the total electronic entropy vanishes in the limit of zero temperature (T0) and increases smoothly with temperature for all α, consistent with the third law of thermodynamics. Layer-resolved analysis reveals that the doped sheet acquires a larger electronic entropy than the pristine one for 0<α<1, giving rise to a finite entropic polarization. The maximum polarization follows a linear scaling, demonstrating that the entropy imbalance is continuously controlled by the hopping asymmetry and does not involve critical behavior. These results establish a direct connection between doping-induced spectral redistribution and thermodynamic layer polarization in bilayer graphene. Full article
(This article belongs to the Section Condensed Matter Physics)
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22 pages, 3405 KB  
Article
A Simple Argument That Small Hydrogen May Exist
by J. Va’vra
Physics 2026, 8(2), 45; https://doi.org/10.3390/physics8020045 - 7 May 2026
Viewed by 1073
Abstract
This paper examines whether a compact electron–proton configuration (“small hydrogen”) with a characteristic radius of a few femtometers is excluded by basic relativistic kinematics and simple stationarity constraints. Motivated by earlier discussions of formally deep relativistic energy scales in Dirac-based treatments, a phenomenological, [...] Read more.
This paper examines whether a compact electron–proton configuration (“small hydrogen”) with a characteristic radius of a few femtometers is excluded by basic relativistic kinematics and simple stationarity constraints. Motivated by earlier discussions of formally deep relativistic energy scales in Dirac-based treatments, a phenomenological, virial-inspired energy-balance framework that incorporates relativistic kinetic energy, finite-size regularization of the central field, and order-of-magnitude spin–magnetic and spin–orbit contributions is developed in this paper. Within this framework, self-consistent characteristic scales associated is obtained with a hypothetical compact configuration without invoking Dirac or quantum-electrodynamics (QED) bound-state eigenvalues. The resulting scales—namely, a central energy scale of about 260 keV and a characteristic spin-dependent scale of order ΔEspin ≈ 100 ± 20 keV—define concrete experimental and observational energy ranges of interest. The present study does not establish the existence, formation probability, lifetime, or dynamical stability of such states. Rather, it shows that relativistic kinematics, finite-size effects, and virial-inspired stationarity constraints do not, by themselves, rule out compact stationary electron–proton configurations within the assumptions of the model. If such states were realized in nature and possessed radiative or interaction channels, those states may have implications for astrophysics, fusion concepts, and dark-matter phenomenology. Full article
(This article belongs to the Section Quantum Mechanics and Quantum Systems)
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18 pages, 1233 KB  
Article
Transverse Dynamics of Strange Hadrons in Relativistic Heavy-Ion Collisions
by Diana Deară, Oana Ristea, Cătălin Ristea and Alexandru Jipa
Physics 2026, 8(2), 44; https://doi.org/10.3390/physics8020044 - 7 May 2026
Viewed by 737
Abstract
We present a study of the mean transverse momentum pT of identified strange hadrons (KS0,Λ,Λ¯,Ξ,Ξ¯+,ϕ,Ω,Ω¯+) produced in [...] Read more.
We present a study of the mean transverse momentum pT of identified strange hadrons (KS0,Λ,Λ¯,Ξ,Ξ¯+,ϕ,Ω,Ω¯+) produced in Au+Au collisions at RHIC-BES energies (the nucleon–nucleon center-of-mass energy sNN=7.7 GeV,11.5 GeV,19.6 GeV,27 GeV and 39 GeV). The mean transverse momentum is obtained from transverse momentum spectra of the strange hadrons as measured by the STAR experiment and its dependence on the number of participants Npart is studied. For RHIC-BES energies, experimental data indicate a centrality dependence of pT, with an increase towards central collisions. This dependency is described using a power-law function to fit the data. The power-law exponent α is used to characterize the degree of flattening of pT with respect to Npart and its dependency on the collision energy and particle mass is studied. Special emphasis is placed on ϕ-meson that has a smaller interaction cross-section, thus reflecting the properties of the early stages of the system’s evolution. The pT of ϕ-mesons produced in Au+Au collisions at RHIC-BES energies are compared with the results obtained in Au+Au collisions at higher RHIC energies and in Pb+Pb collisions at SPS and LHC energies. A distinct energy dependence of ϕpT values is identified. Furthermore, data indicate, when comparing peripheral and central heavy-ion collisions, that ϕ-meson pT increases with system size, following two distinct trends. The results are compared with the predictions of the default and string-melting versions of the AMPT generator. We observe that the string-melting AMPT version describes the strange meson pT, but underpredicts the strange baryon pT centrality dependence. The default AMPT overpredicts the KS0 and ϕ meson pT centrality dependence, while the strange baryon data are in general better described by this version of the model. The exponent α obtained from AMPT-simulated results does not describe the measurements satisfactorily. Full article
(This article belongs to the Special Issue High Energy Heavy Ion Physics—Zimányi School 2024)
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16 pages, 35402 KB  
Article
JefiFast: Accelerating Jefimenko’s Equations with Memory-Centric Optimizations and Multi-GPU Parallelism
by Bing He, Shengyu Peng, Nan Sun, Guoliang Li, Xiaofei Zhu, Peng Xu and Xiaowei Shen
Physics 2026, 8(2), 43; https://doi.org/10.3390/physics8020043 - 7 May 2026
Viewed by 537
Abstract
As a foundation for numerical solvers in computational electromagnetics, particularly for multiphysics and electromagnetic compatibility applications, Jefimenko’s equations offer a generalized solution to Maxwell’s equations, enabling the direct computation of electromagnetic fields from time-dependent source distributions without the boundary-condition artifacts inherent to grid-based [...] Read more.
As a foundation for numerical solvers in computational electromagnetics, particularly for multiphysics and electromagnetic compatibility applications, Jefimenko’s equations offer a generalized solution to Maxwell’s equations, enabling the direct computation of electromagnetic fields from time-dependent source distributions without the boundary-condition artifacts inherent to grid-based methods. However, the numerical integration of these equations is computationally intensive, typically scaling as O(NsNo) for Ns source points and No observation points. In this paper, we present JefiFast, a highly optimized graphics processing unit (GPU) implementation that significantly outperforms the state-of-the-art JefiGPU algorithm. We identify that previous implementations are strictly memory-bound due to inefficient global memory transactions and a lack of data reuse. JefiFast addresses these bottlenecks through four key optimizations: (i) a packed memory layout (PML) using an array-of-structures approach to ensure coalesced memory access for source densities and their derivatives; (ii) geometry-aware shared memory tiling strategies that maximize L2 (level-2) cache hit rates and on-chip data reuse; (iii) pre-computation of time derivatives to minimize redundant arithmetic operations; and (iv) a robust observation domain decomposition strategy that enables linear scaling across multiple GPUs. Benchmarks demonstrate that JefiFast achieves speedups ranging from 4.08 times (for 303 grids on a single NVIDIA V100 graphic processor) to 84.51 times (for 503 grids on 4 NVIDIA V100 processors) compared to the baseline. Notably, for a 503 grid on a single GPU, JefiFast reduces execution time from about 51 min to just about 2.6 min (19.54 times speedup). These performance advances make high-resolution relativistic heavy-ion collision simulations feasible in near real-time. Full article
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7 pages, 545 KB  
Communication
A Simple Introduction to Gravitomagnetic Effects
by Elmo Benedetto
Physics 2026, 8(2), 42; https://doi.org/10.3390/physics8020042 - 1 May 2026
Viewed by 759
Abstract
General relativity is often perceived by undergraduate and advanced high-school students as conceptually and mathematically inaccessible. This paper does not provide new results in gravitation but rather introduces a lucid pedagogical framework for understanding gravitomagnetic effects in rotating systems. Starting from the Langevin [...] Read more.
General relativity is often perceived by undergraduate and advanced high-school students as conceptually and mathematically inaccessible. This paper does not provide new results in gravitation but rather introduces a lucid pedagogical framework for understanding gravitomagnetic effects in rotating systems. Starting from the Langevin metric, which describes flat spacetime in a uniformly rotating reference frame, the paper considers an apparent paradox: two clocks moving with identical velocities in an inertial frame but located at different radii on a rotating platform. While the equality of proper time of the clocks is expected in the inertial frame, its reconstruction in the rotating frame is not immediately transparent. It is shown here that this equality emerges from an exact compensation between three distinct contributions: a centrifugal potential term, a kinematic time dilation term, and a velocity-dependent term being formally analogous to a gravitomagnetic potential. The explicit identification and interpretation of these contributions constitute the pedagogical significance of this paper. Although the consideration presented is performed in flat spacetime, the formal analogy with gravitomagnetic effects provides students with an accessible pathway to more advanced concepts such as frame-dragging and the Sagnac effect, while highlighting the importance of velocity-dependent interactions in relativistic physics. Full article
(This article belongs to the Section Physics Education)
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13 pages, 476 KB  
Article
Albedo-Induced Perturbation in the Sitnikov Three-Body Problem
by M. Shahbaz Ullah, M. Javed Idrisi and Sergey Ershkov
Physics 2026, 8(2), 41; https://doi.org/10.3390/physics8020041 - 13 Apr 2026
Viewed by 853
Abstract
In this paper, the circular Sitnikov three-body problem is studied under the combined influence of radiation pressure and albedo. The model consists of two equal-mass primaries moving in circular orbits about their center of mass and an infinitesimal body constrained to oscillate along [...] Read more.
In this paper, the circular Sitnikov three-body problem is studied under the combined influence of radiation pressure and albedo. The model consists of two equal-mass primaries moving in circular orbits about their center of mass and an infinitesimal body constrained to oscillate along the perpendicular axis. The radiative emission from one primary and the reflected radiation from the other are incorporated into the effective potential through radiation and reflectivity parameters. Using the Jacobi integral, we determine the energetically admissible region for vertical motion and examine how radiative effects modify the accessible phase space. The study shows that the system admits a single vertical equilibrium point at the origin, which remains linearly stable within the physically admissible parameter range. Radiation and albedo reduce the effective restoring force and increase the oscillation period, producing a measurable rescaling of the physical time without altering the geometrical structure of the phase trajectories. The phase-space dynamics are further explored by means of Poincare (first-return) maps obtained from numerical integration of the nonlinear equation of motion. The resulting invariant curves confirm that the motion remains regular and bounded, while their progressive contraction reflects the reduction in the oscillation amplitude with increasing radiative effects. Overall, the results show that albedo acts as a quantitative modifier of the vertical Sitnikov dynamics by changing the effective potential, the admissible energy domain, and the observable time scale, without generating new qualitative phase-space structures. Full article
(This article belongs to the Section Mathematical Physics and Mathematical Methods)
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16 pages, 6395 KB  
Review
Casimir Effect with Dielectric Matter in Salted Water and Implications at the Cell Scale
by Larissa Inácio, Felipe S. S. Rosa, Astrid Lambrecht, Paulo A. Maia Neto and Serge Reynaud
Physics 2026, 8(2), 40; https://doi.org/10.3390/physics8020040 - 10 Apr 2026
Viewed by 1549
Abstract
The Casimir interaction in salted water contains a universal contribution of electromagnetic fluctuations that makes it of a longer range than previously thought. The universal contribution dominates non-universal ones at the distances relevant for actin fibers inside the cell. We discuss universal and [...] Read more.
The Casimir interaction in salted water contains a universal contribution of electromagnetic fluctuations that makes it of a longer range than previously thought. The universal contribution dominates non-universal ones at the distances relevant for actin fibers inside the cell. We discuss universal and non-universal contributions with a model mimicking biological matter. We also show that the universal Casimir effect should have crucial implications at the cell scale. Full article
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19 pages, 1610 KB  
Article
First- and Second-Order Raman Scattering and Photorefraction in Nonlinear Optical Crystal LiNbO3:Y3+(0.46 wt%)
by Nikolay V. Sidorov, Mikhail N. Palatnikov, Alexander Y. Pyatyshev and Alexander V. Skrabatun
Physics 2026, 8(2), 39; https://doi.org/10.3390/physics8020039 - 9 Apr 2026
Viewed by 1529
Abstract
It is found that the speckle structure of the photoinduced light scattering indicatrix of the LiNbO3:Y3+(0.46 wt%) crystal and its behavior with the time of crystal irradiation with a laser undergo an atypical behavior caused by the features of [...] Read more.
It is found that the speckle structure of the photoinduced light scattering indicatrix of the LiNbO3:Y3+(0.46 wt%) crystal and its behavior with the time of crystal irradiation with a laser undergo an atypical behavior caused by the features of the dissipation processes of laser-induced defects in the crystal. In the frequency range of 100–4000 cm−1, the Raman spectra of the LiNbO3:Y3+(0.46 wt%) single crystal were recorded upon excitation by visible (532 nm) and near-IR (785 nm) laser radiation. Five second-order Raman scattering lines were detected in the frequency range of 1000–2100 cm−1, with the frequencies of two of them (of about 1790 cm−1 and 1940 cm−1) somewhat exceeding the doubled value of the frequencies of fundamental vibrations of the 4A1(z)LO (longitudinal optical) and 9E(x,y) symmetry types, which allows us to attribute these lines to the overtones of the fundamental vibrations of 4A1(z)LO and 9E(x,y). It is found that only one Raman scattering line is observed in the region of stretching vibrations of OH-groups (3200–3800 cm−1). The frequency of this line is found to depend on the scattering geometry, varied within 3431–3438 cm−1, and to be shifted to the low-frequency region by about 30–50 cm−1 relative to the frequencies in the IR absorption spectrum. This finding may be due to the alternative prohibition rule due to the presence of the center of symmetry of the oxygen octahedra O6 of the crystal structure. Full article
(This article belongs to the Section Condensed Matter Physics)
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16 pages, 597 KB  
Communication
The Influence of a Magnetic Field on Wave Processes in a Viscous Conductive Liquid on a Rotating Wall
by Anatoly A. Gurchenkov and Ivan A. Matveev
Physics 2026, 8(2), 38; https://doi.org/10.3390/physics8020038 - 8 Apr 2026
Viewed by 593
Abstract
The evolution of the flow of a viscous, electrically conductive, incompressible fluid on a rotating wall in the presence of a magnetic field is studied. The wall forms an arbitrary angle with the axis of rotation. The unsteady flow is induced by longitudinal [...] Read more.
The evolution of the flow of a viscous, electrically conductive, incompressible fluid on a rotating wall in the presence of a magnetic field is studied. The wall forms an arbitrary angle with the axis of rotation. The unsteady flow is induced by longitudinal oscillations of the wall and a suddenly applied magnetic field directed normal to the wall. An analytical solution to the three-dimensional unsteady magnetohydrodynamic equations is presented for the case of infinitely high fluid conductivity. The velocity field and induced magnetic field in the flow of a viscous, electrically conductive fluid are determined. A number of special cases of wall motion are considered. Based on the obtained results, the influence of the magnetic field on the characteristics of the waves emitted by the wall is investigated. Full article
(This article belongs to the Section Classical Physics)
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34 pages, 5761 KB  
Article
Wigner Quasiprobability of Coherent Phase States
by Alfred Wünsche
Physics 2026, 8(2), 37; https://doi.org/10.3390/physics8020037 - 8 Apr 2026
Viewed by 793
Abstract
The Wigner quasiprobability, along with some of its essentialproperties, is introduced and discussed in two versions, first covering real canonical variables such as W(q,p) and second a pair of complex conjugate coordinates such as [...] Read more.
The Wigner quasiprobability, along with some of its essentialproperties, is introduced and discussed in two versions, first covering real canonical variables such as W(q,p) and second a pair of complex conjugate coordinates such as W(α,α*). The reconstruction of the density operator ϱ of states is also given. Building upon the Susskind–Glogower concept of quantum phase operators, further aspects of phase operator algebras in the quantum optics of a harmonic oscillator are discussed in relation to the realization of the su(1,1) Lie algebra. Coherent phase states |ε are introduced in analogy to the common coherent states |α in two ways, as both eigenstates of certain operators and as states generated from a ground state |0 by operators of the Lie group SU(1,1). The limiting transition to the non-normalizable Fritz London phase states |eiφ on the unit circle and an (over)-completeness relation for the coherent phase states are derived. The Wigner quasiprobability W(q,p) for the coherent phase states is calculated and graphically represented. From the Wigner quasiprobability, a phase distribution W(φ) is calculated by integrating over the radius, and its uncertainty is defined and presented. The Hilbert–Schmidt distance is discussed as a measure of the non-classicality of states, where most of our with Viktor Dodonov work was carried out. Full article
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12 pages, 1563 KB  
Article
Controlling Magnetic Energy Confinement in One- and Three-Dimensional Systems
by José Holanda
Physics 2026, 8(2), 36; https://doi.org/10.3390/physics8020036 - 3 Apr 2026
Viewed by 818
Abstract
This paper investigates the control of magnetic energy confinement in one- and three-dimensional magnetic systems by systematically accounting for magnetic interactions. The analysis provides new insight into magnetic behavior at the nanoscale and introduces a simulation-based framework that clearly distinguishes between magnetizing and [...] Read more.
This paper investigates the control of magnetic energy confinement in one- and three-dimensional magnetic systems by systematically accounting for magnetic interactions. The analysis provides new insight into magnetic behavior at the nanoscale and introduces a simulation-based framework that clearly distinguishes between magnetizing and demagnetizing interaction regimes. Within this framework, magnetic energy confinement is rigorously defined and can be quantitatively controlled through the underlying interaction landscape. To validate this approach, extensive numerical simulations were performed on representative one- and three-dimensional nanostructures, including individual nanowires and hexagonal arrays of nanowires. Each nanowire was modeled as a chain of interacting ellipsoidal grains, enabling an accurate description of the complex magnetic interactions governing energy confinement in these systems. Full article
(This article belongs to the Section Applied Physics)
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14 pages, 319 KB  
Article
Non-Commutative Integration Method and Generalized Coherent States
by Alexander Breev and Dmitry Gitman
Physics 2026, 8(2), 35; https://doi.org/10.3390/physics8020035 - 2 Apr 2026
Viewed by 602
Abstract
The relationship between states obtained by the non-commutative integration method of the Schrödinger equation on Lie groups and generalized coherent states is investigated. It is shown that such solutions belong to the class of generalized coherent states when the corresponding λ-representation is [...] Read more.
The relationship between states obtained by the non-commutative integration method of the Schrödinger equation on Lie groups and generalized coherent states is investigated. It is shown that such solutions belong to the class of generalized coherent states when the corresponding λ-representation is real. Full article
10 pages, 279 KB  
Article
A Scalar Particle Under Effects of a Magnetic Field Induced by the Lorentz Symmetry Violation
by Fernando M. O. Moucherek and Ricardo L. L. Vitória
Physics 2026, 8(2), 34; https://doi.org/10.3390/physics8020034 - 2 Apr 2026
Viewed by 819
Abstract
We investigate the effects of Lorentz symmetry violation (LSV) on a scalar particle via a non-minimal coupling in the Klein–Gordon equation within the charge–parity–time CPT-odd gauge sector. Through an analytical approach, we derive bound-state solutions for two distinct anisotropic backgrounds: time-like and space-like. [...] Read more.
We investigate the effects of Lorentz symmetry violation (LSV) on a scalar particle via a non-minimal coupling in the Klein–Gordon equation within the charge–parity–time CPT-odd gauge sector. Through an analytical approach, we derive bound-state solutions for two distinct anisotropic backgrounds: time-like and space-like. In the time-like case, the LSV induces an effective centrifugal potential, modifying the angular momentum spectrum. When a hard-wall confining potential is included, discrete energy levels emerge, explicitly dependent on the LSV parameters. In the space-like scenario, the particle becomes confined by a Coulomb-type potential induced by the LSV, leading to a quantized energy spectrum that reduces to the free-particle limit when the LSV parameters vanish. Our results illustrate how spacetime anisotropies, encoded in a background vector field, can significantly alter the quantum dynamics of scalar particles in the presence of a magnetic field. Full article
(This article belongs to the Section High Energy Physics)
23 pages, 590 KB  
Article
Why the Casimir Force for Magnetic Metals Computed by the Lifshitz Theory Using the Drude Model Disagrees with the Measurement Data
by Galina L. Klimchitskaya, Constantine C. Korikov and Vladimir M. Mostepanenko
Physics 2026, 8(2), 33; https://doi.org/10.3390/physics8020033 - 1 Apr 2026
Cited by 1 | Viewed by 1292
Abstract
We consider the Casimir force in configurations with magnetic metal plates and analyze the reasons why the predictions of the Lifshitz theory using the dielectric permittivity of the Drude model are inconsistent with the measurement data. For this purpose, the contributions of the [...] Read more.
We consider the Casimir force in configurations with magnetic metal plates and analyze the reasons why the predictions of the Lifshitz theory using the dielectric permittivity of the Drude model are inconsistent with the measurement data. For this purpose, the contributions of the electromagnetic waves with the transverse magnetic and transverse electric polarizations to the Casimir force are computed using the Lifshitz theory expressed in terms of the pure imaginary Matsubara frequencies. Furthermore, the fractions of the evanescent and propagating waves in these contributions are found using the equivalent formulation of the Lifshitz theory along the real frequency axis. All computations are performed for Au–Ni and Ni–Ni plates using the Drude model and the experimentally consistent plasma model over the separation region from 0.5 to 6 μm, where the total force value is determined by the conduction electrons. It is shown that the transverse magnetic contribution to the Casimir force does not depend on the model of the dielectric permittivity used, allowing the total difference between the predictions of the Lifshitz theory using the Drude model and the measurement data to be determined by the transverse electric contribution. In doing so, as opposed to the case of nonmagnetic metals, both fractions of the evanescent and propagating waves in this contribution depend on the model of the dielectric permittivity used in computations, whereas the magnetic properties of the plate metal influence the Casimir force solely through the fraction of the propagating waves in the transverse electric contribution. The issue of a more adequate theoretical description of the electromagnetic response of magnetic metals is discussed. Full article
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