物理最新文献

We investigate the differential-reflectance signature of a Fano-type plasmonic response in a reflective plasmonic grating structure. A double-layer Au diffraction grating—designed to operate in contact with ethanol under 780-nm illumination from the analyte side—is fabricated on a sapphire substrate using electron-beam lithography and vacuum deposition. Rigorous coupled-wave analysis reveals an asymmetric reflectance peak with steep angular variation, while numerical differentiation of the reflectance spectrum produces a sharp differential reflectance dip. Reflectance mapping combined with Rayleigh anomaly and propagating surface plasmon dispersion relations, along with quantitative near-field analysis, indicates that the observed response is consistent with a Fano-type plasmonic response involving localized and propagating plasmonic components. Angular reflectance measurements reproduce both the asymmetric reflectance peak and differential reflectance dip, in good agreement with the simulations. The potential sensing performance is evaluated from the simulated refractive-index sensitivity and experimentally obtained linewidth. These results demonstrate that differential reflectance provides a useful readout of a Fano-type plasmonic response in reflective plasmonic grating sensors, particularly for low-refractive-index liquids.

We formulate a holographic weak-link construction in which Josephson transport is controlled by a near-extremal Reissner–Nordstrom–AdS background while the superconducting junction is carried by a dynamically distinct Abelian-Higgs probe sector. The RN–AdS geometry is supported by a homogeneous background Maxwell field ({mathcal {B}}_mu ,) whereas the junction gauge field (A_mu ) and charged scalar (Psi ) enter the action with an overall factor (lambda ^2.) After deriving the field equations, the limit (lambda rightarrow 0) leaves the nonlinear Maxwell–scalar equations intact on a fixed RN–AdS geometry while their stress tensor affects the metric only at ({mathcal {O}}(lambda ^2).) This makes the fixed-background approximation a controlled leading-order truncation even for a finite spatial modulation of the probe chemical potential. The Josephson phase difference is defined from the gauge-invariant boundary data of the probe condensate, not from the RN charge itself. We identify the current-phase relation, critical current, coherence length, and small-phase stiffness as the principal transport quantities. In the SNS regime, the critical current and midpoint condensate probe the same spatial proximity scale, while higher harmonics diagnose enhanced transparency or departure from the opaque weak-link limit. The near-extremal RN–AdS throat introduces a radial scale distinct from the spatial proximity length. We derive its domain of validity and distinguish the AdS(_2) response coefficient from the Josephson current obtained after ultraviolet matching. For the canonical scalar mass (m^2L^2=-2,) the homogeneous normal probe throat violates the AdS(_2) stability bound at extremality for every real probe electric field. A real-index power law therefore requires a different stable reference sector and a separate derivation of its overlap with the junction response. The analysis provides a probe formulation, analytic proximity references, and infrared constraints; it does not constitute a numerical solution of the nonlinear RN–AdS junction.

The trace anomaly and anomaly-induced action are evaluated for the two-dimensional 2D vector theory with classical conformal symmetry. Implementing local conformal symmetry while preserving the gauge invariance requires either giving up locality of the classical action or, equivalently, introducing an auxiliary scalar field. The two-dimensional limit in such a theory is singular. However, in the dimensional regularization, the limit (D rightarrow 2) in the one-loop divergence is smooth. As a result, we arrive at the expression for anomaly, which has a rich general structure, typical for the dimensions (D ge 4). For comparison and completeness, we also evaluate anomalies for conformal scalar and fermions, also in the presence of auxiliary external scalars.

We investigate a fifth-order nonlinear Schrödinger equation, the zero- and nonzero-gain conditions on the modulation-instability resonance line acts as a branch selection of rational solutions. The modulational instability suppressing factor dictates from the generalized Darboux transformation: rogue waves with nonzero-gain, and W-shaped rational solitons with zero-gain. This zero-gain branch generates the higher-order rogue wave and the rational solitons. Asymptotic expressions confirm elastic interactions for second-order solitons and a third-order three-channel structure. Residuals validate solutions, proving modulational instability zero-gain selects rational soliton branches in higher-order models.

Graphical abstract

High-order rational soliton branch selection based on the zero-gain condition of modulation instability

This study reveals the zero-gain condition on the modulation instability (MI) resonance lines in the quintic nonlinear Schrödinger equation as a key mechanism for selecting rational wave solution branches. As shown in the figure, MI gain analysis identifies distinct stability regions:

1. 1.

   Non-zero gain branch: a rogue wave structure with dual temporal and spatial localization.

2. 2.

   Zero-gain branch: The selected propagating W-shaped rational soliton exhibits a distinctive peak-valley structure on the background wave and demonstrates channel characteristics of elastic interactions in higher-order scenarios.

This discovery establishes the MI zero-gain condition as an algebraic selection criterion for transitioning from linear analysis to precise nonlinear solution structures.

Semiconductor oxide materials have demonstrated significant potential in ultrafast laser device owing to their broadband spectral response, high damage resistance, and excellent physicochemical stability. In this work, we prepared a rutile-phase titanium dioxide (TiO₂) nanofilm, experimental results show that by integrating the saturable absorber (SA) into a ring fiber cavity, stable conventional soliton mode-locking operation was achieved, with a center wavelength of 1559.49 nm, a 3 dB spectral bandwidth of 16.60 nm, a pulse duration of 1.01 ps, a fundamental repetition rate of 22.1 MHz, and a signal-to-noise ratio (SNR) of 68.61 dB in the radio frequency (RF) spectrum. The prepared TiO₂ exhibits a modulation depth of 5.96% and a saturation intensity of 0.7149 MW/cm². This study verifies the feasibility of rutile-phase TiO₂ as an efficient and stable SA for 1.5 μm band ultrafast fiber laser.

Graphical abstract

We present the Ising noise filter, a highly portable, graph-based filtering algorithm for early-stage background suppression in particle accelerators and astrophysical detectors. Standard noise rejection methods relying on track fitting suffer from severe combinatorial explosion. Our method bypasses this by mapping individual detector hits to a network of binary spins and minimizing an energy functional. The entire algorithm reduces to vectorized array operations, making it fast and easy to deploy. The interaction kernels are physics-informed, tailored to the underlying physics and geometry of the experiment. We demonstrate the efficacy of this approach in two distinct experimental regimes. Applied to the Baikal-GVD neutrino telescope the filter yields fast, standard-quality noise rejection with 97% recall for astrophysical neutrinos. For the SPD detector at the NICA collider the filter attains 96.7% precision and 97.4% recall on a toy Monte Carlo sample. Furthermore, when combined with a Peterson–Hopfield network for track finding, our physics-informed coupling improves the TrackML score from 0.5 to 0.91.

We formulate a compact dynamical representation of quantum-information diagnostics for time-dependent two-mode bosonic systems in terms of the Bogoliubov ratio (lambda _k(eta )=beta _k(eta )/alpha _k(eta )). For vacuum-evolved pure Gaussian pair states generated by a Hermitian quadratic Hamiltonian, (lambda _k) obeys a closed complex Riccati equation. After one partner mode is traced out, the reduced-state spectrum is determined by (q_k=|lambda _k|^2), from which the purity, linear entropy, Rényi-2 entropy, and von Neumann entropy follow directly. These Gaussian results are mathematically equivalent to those obtained from the standard density-matrix or covariance-matrix formalism; the advantage of the ratio representation is a compact separation between model-dependent dynamics and universal state diagnostics. Writing (lambda _k=sqrt{q_k}e^{itheta _k}) further exposes how pair production drives radial growth, whereas frequency rotation and detuning act through the phase and can suppress coherent squeezing accumulation. We also establish an exact extension to non-Gaussian SU(1, 1) sectors. For a lowest-weight Fock seed with conserved number difference d, the same ratio equation governs the evolution, while the reduced spectrum becomes a negative-binomial distribution determined by ((q_k,d)). The Gaussian formulas are recovered at (d=0). Cosmological perturbations and a chirped-pulse optical parametric amplifier illustrate the common dynamical mechanism and its information-theoretic consequences.

In High Energy Physics, as in many other fields of science, the application of machine learning techniques has been crucial in advancing our understanding of fundamental phenomena. Increasingly, deep learning models are applied to analyze both simulated and experimental data. In most experiments, a rigorous regime of testing for physically motivated systematic uncertainties is in place. The numerical evaluation of these tests for differences between the data on the one side and simulations on the other side quantifies the effect of potential sources of mismodelling on the machine learning output. In addition, thorough comparisons of marginal distributions and (linear) feature correlations between data and simulation in “control regions” are applied. However, the guidance by physical motivation, and the need to constrain comparisons to specific regions, does not guarantee that all possible sources of deviations have been accounted for. We therefore propose a new adversarial attack – the CONSERVAttack – designed to exploit the remaining space of hypothetical deviations between simulation and data after the above mentioned tests. The resulting adversarial perturbations are consistent within the uncertainty bounds — evading standard validation checks — while successfully fooling the underlying model. We further propose strategies to mitigate such vulnerabilities and argue that robustness to adversarial effects must be considered when interpreting results from deep learning in particle physics.

Angular-dependent magnetization and anomalous Nernst effect (ANE) measurements were combined to investigate the relationship between in-plane magnetic anisotropy and thermomagnetic response in an as-deposited 60 nm Co₂MnAl thin film produced by DC magnetron sputtering at room temperature. The magnetic hysteresis loops exhibit a two-step reversal process, comprising a gradual magnetization rotation followed by a sharper switching event, consistent with two effective uniaxial anisotropy contributions. The angular-dependent ANE curves display pronounced changes in amplitude and shape, reflecting the sensitivity of the measured voltage to the magnetization component transverse to the electrical contacts. When the magnetic field is applied along the voltage-contact axis, the maximum ANE voltage increases linearly with the applied temperature difference, reaching approximately (:33text{}mu:text{V}) at (:{Delta:}T=30text{}text{K}:)and yielding an effective voltage responsivity of (S_{eff}=1.09;mu VK^{-1}). Using the estimated temperature difference across the CMA layer, an anomalous Nernst coefficient of (S_{ANE}=0.30;mu VK^{-1})was obtained. Theoretical calculations based on two ferromagnetically exchange-coupled macrospins with distinct uniaxial anisotropies reproduce the principal field- and angle-dependent features of both the magnetization and ANE responses, whereas a purely uniaxial model is insufficient to describe the experimental behavior. These results establish the combined use of magnetometry and angular-dependent ANE measurements as a vector-sensitive approach for probing dual-anisotropy magnetization reversal in structurally disordered Co₂MnAl thin films.