物理最新文献

The effect of gravity is a key factor in understanding the physical phenomenon. Quantizing gravity is challenging task due to weak interactions of gravity in quantum world. The quantum nature of gravity can be witnessed by entanglement in an interferometric platform [Phys. Rev. D 105, 086024 (2022)]. A natural question arises concerning whether the quantization of gravity can be observed via other means. In this work, we propose an effective approach to witnessing the gravity-induced quantumness by quantum uncertainty relations, including entropy-based and coherence-based uncertainty relations. The theoretical frameworks for wave-particle, entropic uncertainty and coherence are established, which can prove the quantum nature of gravity. The three-measurement entropic uncertainty and coherence exhibit the oscillatory features for the gravity-induced phases in the interferometric scheme. It is found that the evolutionary dynamics of coherence is inversely correlated with the measured uncertainty. It can be interpreted that the reduction of systemic quantum resource leads to the increase of entropic uncertainty, and vice versa. When the entropic uncertainty reaches zero, systemic coherence is the maximum value, providing a viable physical explanation for the gravity-induced quantumness. It shows that the entropic uncertainty and coherence can be regarded as the reliable indicators for capturing the gravity-induced quantumness. Compared to entanglement-based gravity quantization scheme, it shows that the capabilities are equivalent for detecting the gravity-induced quantumness using entropy uncertainty, coherence, and entanglement. The results could lay a solid theoretical foundation for the potential applications of quantum gravity in quantum information science.

In this paper, we perform small perturbations around the circular timelike orbit in the equatorial plane of the Horndeski rotating black hole, and analyze the effects of Horndeski hair on the three fundamental frequencies of the epicyclic oscillations. Since this operation can model the quasiperiodic oscillations (QPOs) phenomena of the surrounding accretion disc, we then employ the MCMC simulation to fit the theoretical results with three QPO events, including GRO J1655-40, XTE J1859+226 and H1743-322, and constrain the characteristic radius r, black hole mass M and spinning parameter a, and the Horndeski hair parameter h. Our constraint on the Horndeski hair parameter is much tighter than QPOs simulation from the existed accretion models, suggesting slight deviation from classical Kerr black hole.

In this work, we construct new classes of topological black hole solutions in anti-de Sitter (AdS) spacetime using a novel model of nonlinear electrodynamics called Modification Maxwell (ModMax) and Modification phantom or Modification anti-Maxwell (ModAMax). We then evaluate the thermodynamic quantities and verify the first law of thermodynamics. Our study examines how the parameters of the ModMax and ModAMax fields, as well as the topological constant, affect the black hole solutions, thermodynamic quantities, and local and global thermal stabilities. Furthermore, within the framework of extended phase space thermodynamics, we analyze the Joule–Thomson expansion process and determine the inversion curves. This analysis reveals that the ModMax and ModAMax parameters significantly alter the cooling and heating behavior of these AdS black holes, depending on their topology. Finally, by treating these topological Mod(A)Max AdS black holes as heat engines, we assess their efficiencies, demonstrating that the parameters of nonlinear electrodynamics and horizon topology play crucial roles in enhancing or suppressing the system’s thermodynamic performance.

Praseodymium (Pr³⁺) doped magnesium aluminate (MgAl₂O₄) and barium aluminate (BaAl₂O₄) nanophosphors were synthesised via the sol–gel method. XRD confirmed the formation of single-phase aluminate structures with average crystallite sizes of 18 nm and 15 nm for MgAl₂O₄: Pr³⁺ and BaAl₂O₄: Pr³⁺, respectively. MgAl₂O₄: Pr³⁺ shows irregular, densely packed grains with rough surfaces, while BaAl₂O₄: Pr³⁺ consists of smaller, nearly spherical particles with uniform distribution and minimal agglomeration. Absorption studies for both samples exhibited broad bands in the 600–700 nm range, indicating strong coupling with the host lattices. PL spectra demonstrated host-dependent emission characteristics. MgAl₂O₄: Pr³⁺ showed intense red emissions with peaks at 650 nm (³P₀ → ³F₂) and 710 nm (³P₀ → ³F₃) emissions, while BaAl₂O₄: Pr³⁺ exhibited prominent blue emission at 490 nm (³P₀ → ³H₄) along with weaker green-yellow emissions in the 530–580 nm. These unique emission properties highlight MgAl₂O₄: Pr³⁺ as a promising red-emitting phosphor, while BaAl₂O₄: Pr³⁺ can be used for blue-emitting applications in solid-state lighting and optoelectronic devices.

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A single-degree-of-freedom periodically forced oscillator with coupled clearance and friction nonlinearities is investigated. By analyzing the phase-space conditions governing free sliding, impact, and stick motion, and employing associated Poincaré maps, the dynamics of stick–slip periodic motions are systematically characterized. Particular emphasis is placed on the distribution and transition of periodic motions in the two-parameter space. The occurrence of bursting oscillations in the low-frequency region is revealed and the influence of key structural parameters on stick–slip behavior is examined. The results indicate that stick–slip motion predominantly occurs in regions characterized by low-frequency and small-clearance. Under the induction of grazing bifurcations, the transition toward stick motion is marked by an increase in the number of impacts, a decrease in impact velocity, and a contraction of the frequency band. The transitions between adjacent periodic motions are primarily governed by the synergistic effects of grazing, saddle-node, and sliding bifurcations. Owing to the irreversibility of the transition paths, multi-stability regions emerge, including co-existing states induced by grazing-(saddle-node), grazing-sliding, and doubling-sliding bifurcations. Furthermore, the increase in damping ζ suppresses multi-impact motions, resulting in improved system smoothness and stability along with reduced structural wear; however, it concurrently induces a rise in energy consumption.

We develop and apply the Batalin–Fradkin–Vilkovisky (BFV) formalism for the covariant quantization of generic off-diagonal solutions of the Einstein equations in general relativity (GR). In the classical regime, such nonholonomic configurations are formulated entirely within GR and are characterized by nonlinear symmetries of generating functions, running cosmological constants, integration functions, and effective matter sources. These constructions are further extended to quantum gravity (QG) models involving effective local Lorentz symmetry violations and anisotropic scaling, as realized in Hořva–Lifshitz (HL)-type theories. The classical geometric framework is formulated on Lorentz manifolds endowed with nonholonomic 2+2 and 3+1 splitting structures and subsequently generalized to quantum configurations determined by HL-type generating functions. The 2+2 dyadic splitting, incorporating connection distortions, provides a systematic method for constructing exact and parametric classical and quantum solutions described by generating functions and effective sources depending on all spacetime coordinates, physical constants, and anisotropic scaling or deformation parameters. The complementary 3+1 splitting allows for a consistent implementation of the BFV quantization procedure. We demonstrate the renormalizability of off-diagonal quantum HL-type deformations of GR. The resulting classical and quantum nonholonomic BFV models represent viable candidates for asymptotically free theories of gravity and may provide a mechanism for resolving unitarity issues in QG. In appropriate classical limits, the framework reproduces physically relevant off-diagonal GR solutions with or without locally anisotropic scaling, offering potential applications to nonlinear classical and quantum phenomena in accelerating cosmology and dark energy and dark matter physics.

The selection of precursor materials is of foremost importance in enhancing the electrochemical performance of electrode materials utilized in supercapacitors. This investigation carefully assesses the influence of various salts derived from cadmium, namely cadmium nitrate (Cd (NO₃) ₂), cadmium acetate (Cd (CH₃COO) ₂), and cadmium sulfate (CdSO₄), on the structural, morphological, and electrochemical characteristics of cadmium electrodes. The results highlight how differences in precursor materials can lead to significant variations in surface area and overall energy storage capability, thereby impacting the efficiency of the supercapacitor. A comprehensive understanding of the correlation between precursor selection and material performance is vital for propelling the advancement of supercapacitor technology, as it facilitates the design of electrodes with customized properties to meet specific application requirements. The salts function as initial agents for producing cadmium-centric nanostructures via a one-step hydrothermal method, following which they find application in supercapacitor electrode fabrication. The materials produced are analyzed through techniques such as X-ray diffraction, Field Emission Scanning Electron Microscopy, Cyclic Voltammetry, Chronopotentiometry, and Electrochemical Impedance Spectroscopy to evaluate their crystallinity, surface structure, and capacitive behavior. Electrochemical studies reveal that the choice of precursor significantly influences ion diffusion, charge storage capacity, and overall energy density. Among the tested precursors, Cadmium Nitrate salt demonstrates superior electrochemical properties, exhibiting a high specific capacitance, i.e.,.275.69 F/g, excellent rate capability. This work provides valuable insights into the optimization of precursor selection for enhanced energy storage performance in Cadmium-based Supercapacitors.

Electromagnetic induction is crucial for understanding the heart’s electrical and chemical dynamics and detecting functional abnormalities. In this study, we examine a modified FitzHugh-Nagumo (FHN) model incorporating standard diffusion and a feedback gain parameter. Through multiple-scale expansion, we derive a cubic-quintic complex Ginzburg-Landau (CQCGL) equation governing action potential dynamics, and we construct traveling wave solutions using a modified Hirota bilinear method (HBM). The feedback gain markedly affects action potentials: (i) On the left side, it reduces amplitude, period, and depolarization/repolarization duration before the transition region. (ii) On the right side, it produces a quasi-periodic structure at (k_{0}=,0.64), favoring rhythm stabilization. Modulational instability (MI) analysis shows that values of (k_{0}) below or above 0.64 destabilize the system. Numerical simulations closely match the analytical results, confirming the model’s validity. Biologically, these findings highlight electromagnetic induction as a key modulator of cardiac function, influencing action potentials through ion-channel regulation and gap junction coupling, and shaping arrhythmia dynamics.

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