Papers

Kerr microcombs provide a compact route to broadband optical frequency grids, yet the primary comb states formed at the onset of Kerr-comb generation have received little attention as metrological objects. Here we characterize the coherence and frequency stability of pair-generated primary-comb tones in a silicon nitride microresonator using synchronized multi-channel frequency counting referenced to a hydrogen-maser-stabilized difference-frequency comb, enabling direct measurement of temporal fluctuations and correlations among the pump, signal, and idler tones. We show that the generated tones are strongly constrained by parametric energy conservation: under weakly locked conditions with MHz-level frequency excursions, the residual deviation from $2f_p=f_s+f_i$ remains sub-hertz in the mean, and the signal-idler regression deviates from the ideal $-1$ response by only $2.4\times10^{-9}$. When two of the three tones are tightly phase-locked, the energy-conservation residual of the full pump-signal-idler triad, equivalently the deviation of the measured idler from the value inferred from the locked pump and signal, reaches a fractional-instability floor near $6 \times 10^{-16}$ at $\tau\approx100~\mathrm{s}$. This demonstrates metrological-level preservation of the parametric constraint while revealing subtle mode-dependent noise transfer. Together, these results establish primary Kerr tones as a strongly correlated chip-scale parametric frequency triad suitable for demanding precision-frequency applications.

A compressible capillary drop differs from an incompressible one in that its radius is a dynamical degree of freedom. When the drop is sufficiently small, this spherical mode can become unstable, defining a critical radius set by the competition between surface tension and compressibility. This paper examines the robustness and physical meaning of that critical radius. For a non-relativistic viscous fluid, starting from the viscous compressible equations and the free-surface stress condition, we derive the radial dispersion relation and show that shear and bulk viscosities change the eigenvalues but not the onset radius. A thermodynamic argument identifies the same radius as the point where the energy of a uniformly compressed drop changes from locally stable to unstable, explaining why the threshold is not set by viscous dissipation. This energetic interpretation can also be applied to a special-relativistic fluid, where the non-relativistic mass-density factor is replaced by the corresponding enthalpy-density factor. We then compare the critical radius with diffuse-interface length scales in two Cahn–Hilliard free-energy models to determine whether the instability can occur within the range of validity of the sharp-interface description. In a symmetric quartic model the critical radius is much smaller than the interface thickness, so the instability is absent throughout that range. In a shallow-well model, however, the critical radius can become parametrically larger than the interface thickness, leaving a range of sharp-interface drops that are unstable. Whether such a range exists therefore depends on the diffuse-interface free-energy model.

The Tellegen limit is the fundamental electromagnetic stability bound on magnetoelectric media. We show that nonlinear magnetoelectric coupling gives rise to a new Tellegen limit, which we term the nonlinear Tellegen limit. Unlike the linear Tellegen limit, which is fixed by material parameters, the nonlinear Tellegen limit is field-tunable – a static electric or magnetic field drives the system toward electromagnetic instability at a material-specific critical field determined by the symmetry-allowed nonlinear magnetoelectric couplings and electromagnetic response. The approach to this limit is accompanied by a field-tunable linear birefringence, whose maximum is bounded by the nonlinear Tellegen limit – beyond which the medium becomes electromagnetically unstable. We demonstrate the nonlinear Tellegen limit and the field-space stability phase diagram in two magnetically ordered material systems – a $d$-wave altermagnet and an M-type hexagonal ferrite – showing that the symmetry of the magnetic point group governs both the structure of the nonlinear magnetoelectric tensor and the resulting electromagnetic instability.

One of the most intriguing phenomena in time varying-media photonics is the amplification of light in a photonic time crystal (PTC). However, studies to date have focused exclusively on PTC-based amplification of coherent light. Here, we theoretically investigate the PTC-based amplification of thermal radiation, specifically blackbody radiation. Such amplification is not only fundamentally intriguing due to the thermal radiation's stochastic nature, but also technologically relevant because thermal radiation's ubiquity, which implies that its amplification generally accompanies that of coherent radiation. For simplicity, and due to the experimental relevance of PTC amplification in transmission lines, we consider amplification in a one-dimensional medium. To analyze the amplification of blackbody radiation in a PTC, we examine the electromagnetic fields' spatial correlations and spatial spectra. We show that the spatial spectra of initially blackbody radiation converge periodically toward Gaussian profiles with progressively increasing amplitudes, coherence lengths, and spatial- and wavenumber-domain purities. We demonstrate that these asymptotic behaviors are governed by the PTC momentum band structure and can be understood using a rotating-wave approximation for the pseudo-Hermitian dynamics of the electromagnetic field in a PTC. Beyond revealing the fundamental evolution of thermal radiation in time-varying media, our numerical framework provides a general approach for analyzing the dynamics of stochastic electromagnetic fields in PTCs and time-varying media, in general. The results also provide physical insight and practical guidance for the design of PTC-based amplifiers, where the concurrent amplification of parasitic thermal radiation may occur.

Accurate geometric calibration is essential for fluoroscopy-guided spinal imaging, digitally reconstructed radiograph (DRR) generation, and 2D–3D vertebral registration. Although calibration quality is typically evaluated using reconstruction-based metrics such as reprojection error, its influence on projection-domain consistency remains poorly understood. This study presents a synthetic framework for evaluating how intrinsic calibration perturbations affect vertebral fluoroscopic projections and downstream registration performance. CT-derived vertebral models and controlled cone-beam imaging geometry were used to generate DRRs with both ground-truth and perturbed intrinsic calibration parameters while maintaining identical anatomy and acquisition pose. Projection-domain changes were quantified using anatomical landmark displacement, contour distance, silhouette overlap, image similarity, and landmark-based 2D–3D registration accuracy in anterior–posterior (AP) and lateral (LAT) views. Results show that even small intrinsic calibration perturbations produce measurable changes in vertebral projection geometry, contour morphology, landmark localization, and DRR appearance. Sensitivity is strongly view dependent, with LAT projections exhibiting substantially greater deformation and anatomical displacement than AP projections. These projection inconsistencies also degrade downstream 2D–3D registration, particularly rotational alignment accuracy. The findings demonstrate that projection-domain consistency complements conventional reconstruction-based calibration metrics and provides a practical framework for assessing calibration robustness. This approach may improve the reliability of DRR generation and fluoroscopy-guided vertebral registration in image-guided spinal applications.

The electronic structure and properties of the thallium monoxide (TlO) molecule, as well as its cation and anion, have been systematically studied using both the relativistic Fock-space coupled cluster method with full inclusion of connected triple excitations and the density functional theory. For the first time, detailed data on the low-lying electronic states of TlO, its cation, and anion have been obtained. The dissociation energies of these systems, the adiabatic electron affinity and vertical ionization potential of TlO, as well as its dipole moment and components of the static polarizability tensor have been calculated. It is shown that the ground electronic state of TlO$^+$ cation is unbound. The obtained characteristics of TlO are highly relevant for interpreting experimental thermochromatography data on compounds of thallium and its superheavy homologue nihonium (element 113).

We study the response of axion topological materials under the presence of external static electric and magnetic fields. We focus on the macroscopic quasi-static magnetoelectric response of topological insulators. We use techniques based on surface variables that have been previously employed in soft condensed matter problems for the description of heterogeneous systems composed of multiple homogeneous materials. A complete description of the whole system is written in terms of surface degrees of freedom, which in this case correspond to effective surface charge and surface current densities. We obtain a set of integral equations satisfied by these variables. We present exact analytic solutions for axial-symmetric cases. We develop a numerical method for the solution of the integral equations by means of a boundary finite element method. We apply the numerical method to topological insulators with different geometries such as spheres, hollow spheres and toroidal surfaces. We show that that a variational principle can be used to recover the surface variables equations.

We argue that it is difficult to investigate the stability of de Sitter inflationary solution in an effective model of Elko fields due to the existence of third-order derivatives of fields, which are unfortunately unconstrained since the number of perturbation equations is not enough. This issue leads to an important question of whether the Elko inflation model is free from an instability or not.

Early-warning signals (EWS) for critical transitions are predominantly based on changes in the dominant eigenvalue of the system's Jacobian-rising variance and lag-1 autocorrelation (AR(1)). However, eigenvalue-based EWS have $O(delta theta^2)$ sensitivity to perturbations, limiting their lead time. We introduce a complementary EWS based on eigenvector rotation, measured by the time-varying elasticity $beta(t) = d log y / d log x$ estimated via a TVP-Kalman filter in log-log space. Since eigenvector sensitivity is $O(delta theta)$, $beta$ is predicted to precede eigenvalue-based signals. We test this hypothesis on 24 years of monthly NASA AIRS data (2002–2026, 284 observations) across three climatically distinct regions (Arctic 65-90N, Tropics 10S-10N, Indian Monsoon), using temperature ($T$) and specific humidity ($q$) as the coupled variables. $beta$ is orthogonal to AR(1) in all regions (Pearson $r approx 0$, n.s.), confirming the distinct information content. Systematic lead-lag analysis reveals that $beta$ precedes AR(1) by 14–24 months, consistent with the $O(delta theta) > O(delta theta^2)$ mechanism. Six simulated systems with known tipping points (Stommel AMOC model, fold bifurcation, logistic map, critical slowing down) further validate that $beta$ leads AR(1) by 39-153 timesteps when the transition involves coupling degradation. The dimensionless nature of $beta$ (scale-free log-log exponent) suggests it may serve as a universal, cross-system EWS, analogous to scaling exponents in critical phenomena.

Simultaneously maximizing power-transfer efficiency and preserving beam quality in plasma-based accelerators is constrained by the transverse beam breakup instability. We present an analytical transverse wake model derived from the plasma wake potential that self-consistently captures deformed cavity boundaries under intense beam loading. This model maps efficiency limits against stability thresholds across a parametric scan to isolate an operating window. Three-dimensional particle-in-cell simulations validate the theoretical model, showing that the analytical centroid evolution matches numerical tracking during the acceleration of a tailored trapezoidal electron bunch over a 1 m propagation distance. The bunch achieves an energy gain of up to 16.5 GeV with nearly preserved transverse emittance, and a wake-to-trailing bunch power-transfer efficiency of nearly 80%, with a final relative energy spread of less than 1.5%. These results show that the efficiency-instability barrier can be circumvented through precise determination of transverse wake force and tailored beam loading, providing a design path toward compact, high-luminosity particle colliders.

Adiabatic invariants play a central role in plasma physics, from magnetic moment and bounce action to wave action in slowly varying media. Their perturbative constructions are often asymptotic, and exhibit factorial growth. We show that such divergence does not by itself imply non-adiabatic transitions. For the reflectionless potential hierarchy associated with Korteweg–de Vries solitons, the exact backward-wave coefficient vanishes, although Berry's phase-integral iteration and the corresponding Lie-transform construction are divergent. Darboux factorisation gives the transmitted wave explicitly. Its modulus and phase define a normal form in which the moving canonical frame is distorted inside the interaction region but returns to its original asymptotic form, leaving only a phase shift and no action change. The exact phase integral is nevertheless an unstable fixed point of the derivative iteration. For the one-soliton symmetry point, an explicit Borel calculation exhibits nonzero singularities in an individual Lie-transform family even though the exact off-diagonal connection coefficient vanishes. Analyticity of the exact connection data then requires these representation-dependent ambiguities to cancel in the completed connection matrix. Thus divergence diagnoses failure of local diagonalisation, whereas the global symplectic connection determines whether reflection survives.

We use the Green's tensor quantization theory for open resonant nanostructures with absorption losses to study cross-phase modulation (XPM) at the single-photon level in nanoscale Kerr-type epsilon-near-zero (ENZ) materials with an effective nonlinear susceptibility integrated inside dual-wavelength nanocavities. We obtain analytical formulas for the XPM frequency shifts in hybrid nanocavities that simultaneously trap a classical probe beam at 1.5 $\mu$m and single-photon pump at 3 $\mu$m wavelengths. We present a comprehensive analysis of the fundamental limits for mid-infrared single-photon detection in the quantum nondemolition modality for nanostructured cadmium oxide (CdO) regions with ENZ-enhanced nonlinearity embedded in a silicon (Si) environment inversely designed by free-form topology optimization. We numerically implement our theoretical results using finite element simulations within the rigorous framework of quasi-normal modes, demonstrating a single-photon XPM frequency shift $\Delta f_s \approx 55.6 \text{ GHz}$ with fractional shift (i.e., frequency pulling) $\Delta f_s / f_s \approx 2.78 \times 10^{-4}$ and addressing the feasibility of detection in the hybrid Si-CdO dual-wavelength nanocavity, either with a classical probe beam or a squeezed probe state, including the contributions of traditional limitations from self-phase modulation noise, thermorefractive noise, shot noise, and free-carrier absorption effects. Finally, we present a comparative size scaling analysis of the XPM phase shift and phase noise contributions for dual-wavelength nanocavities based on CdO and indium tin oxide (ITO) nonlinear ENZ materials. This work establishes a robust benchmark for the engineering of mid-infrared single-photon nonlinear devices such as nondemolition quantum detectors, sensors, and all-optical gates on a solid state photonic platform.

ALFE2 is a front-end ASIC developed for the ATLAS Liquid Argon (LAr) Calorimeter upgrade during the High-Luminosity Large Hadron Collider (HL-LHC) phase. ALFE2 comprises four preamplifier/shaper channels, each providing two distinct gain outputs to cover a 16-bit dynamic range. A robotic system has been developed for the automatic quality control test of ALFE2, and over 10% of the 80,000 chips have been evaluated by September 2025. The evaluation has allowed us to establish grading criteria. Using these criteria, a yield of over 85% was achieved in the evaluation tests, and these criteria are now being applied to the ongoing full-production QC. Irradiation tests were also performed for the quality assurance of ALFE2. No significant performance degradation was observed during the total-ionizing-dose (TID) test. Based on the single-event effect (SEE) test results, an error rate of fewer than 4.6 single-event upsets (SEUs) per day is extrapolated for the entire ATLAS LAr Calorimeter during HL-LHC operation.

Monolayer 1T'-WS2 is predicted to be a two-dimensional topological insulator, but its intrinsic electronic properties are masked by strong interlayer coupling in its metallic and superconducting bulk parent phase, 2M-WS2. Isolating monolayers by mechanical exfoliation is also hindered by this coupling, preventing experimental examination of monolayer properties. Here we show that 2M-WS2 undergoes amine intercalation through a simple wet-chemical reaction, yielding superlattices in which the 1T' layers are structurally preserved but electronically decoupled by neutral molecular spacers. Intercalation expands the interlayer spacing from 0.5 to 1-4 nm and reconstructs the stacking while preserving the intralayer 1T' framework. Controlled (de)intercalation reversibly switches the system between a superconducting metal and an insulator with an activation gap matching that of the isolated monolayer. Density functional theory indicates that the electronically decoupled layers retain the nontrivial Z2 topology of the monolayer. Chiral amine intercalation further induces chiroptical activity in WS2 electronic transitions. Overall, the successful intercalation challenges the long-held view that group VIB dichalcogenides are inert toward neutral-molecule intercalation and demonstrates molecular intercalation as a general chemical route for realizing monolayer-like topological-insulator physics and enabling chiral van der Waals superlattices in bulk single crystals.

Earthquake phase association, which groups seismic phase arrivals into common origins, is a key step towards more complete and reliable seismicity catalogs. It has become a challenging task because of the massive phase datasets produced from dense seismic networks and advanced phase picking methods. Here we present VORA (Voronoi tessellation- and Origin-time-based Rapid Associator), an efficient and scalable earthquake phase associator that treats association as an unsupervised spatio-temporal clustering problem. Specifically, VORA depends on two primary constraints: the estimated earthquake origin time (temporal) and seismic station adjacency (spatial). Recent advances in deep learning models have enabled detection of S- and P-phases with similar effectiveness, making it straightforward to estimate corresponding earthquake origin times from candidate phase pairs given a prescribed range of velocity ratios or directly from raw waveforms. We then leverage the Voronoi diagram to define each station's neighbors, cluster the origin times across neighboring stations, and apply an optional sub-clustering step to separate overlapping events. Benchmarks on synthetic and real datasets show that VORA achieves the fastest runtime and maintains robust performance (high recall and precision) even under intense seismicity. Applying it to a two-week global-scale pick dataset covering the 2019 Ridgecrest earthquake sequence further demonstrates that the same framework scales from local networks to a global station set. VORA requires no training and generalizes across local-to-global regions, varying velocity models, and evolving network geometries, helping to meet the growing demands of expanding seismic networks and the increasing volume of automated phase picks.

Locomotion in low-Reynolds-number environments is achieved through a remarkable diversity of strategies, from flagellar rotation and ciliary beating to large-scale body deformations. A distinct and biologically important class of propulsion arises when surface-anchored filaments grow and collectively reorient - as seen in the cellulose-extruding bacterium Acetobacter xylinum and in recent experiments on actin-propelled synthetic colloids inspired by the motility of Listeria monocytogenes - suggesting that polymerization itself is a generic route to self-propulsion. Developing a theoretical framework for this class of problems requires simultaneously resolving filament kinetics, their orientational dynamics, and fluid-structure interactions - all self-consistently coupled to the resulting locomotion. To address this, we formulate a continuum framework in which the active forces driving locomotion emerge self-consistently from filament nucleation, growth, catastrophe, and hydrodynamic interactions. We show analytically that polymerization-induced compressive forces drive a long-wavelength buckling instability, leading to spontaneous symmetry breaking of the filament carpet and large-scale flows. In coupling this framework to a force- and torque-free motile spheroidal particle, a wide variety of behaviors emerge - this includes spontaneous spinning, directed motility, and chiral swimming - whose selection is governed by the spatial patterning of polymerizing filaments. These results establish a general theoretical foundation for motility, driven by collective dynamics of polymerizing filaments and point towards new design principles for synthetic micron-scale swimmers.

Phobos evolves in a highly dynamical environment where surface-material motion is controlled by the combined effects of self-gravity, time-dependent Martian tides, and inertial forces. In such a low-gravity regime, the displacement of loose material, cannot be inferred from topographic slope alone, making a dynamical approach essential for interpreting Phobos' surface morphology and for supporting the Martian Moons eXploration (MMX) mission led by JAXA. Here, using our RAVEL code, we apply a dynamical model that combines the surface acceleration field with friction on a digital terrain model of Phobos to compute surface regolith trajectories. The model does not aim to predict the triggering of slope failure. Instead, it addresses where material would preferentially move once motion is initiated. This reveals large scale coherent dynamical regions and a sparse network of preferred regolith transport routes, termed here Regolith Migration Pathways (RMPs). The final positions of the RMPs correlate with smooth, low-relief terrains and spectrally neutral units, consistent with depositional mantles formed by long-term regolith infill, whereas rough, high-standing areas with abundant small craters and blue spectral slopes tend to correspond to dynamically active or denuded source regions. In contrast, spectrally red terrains are generally associated with dynamically quiet, morphologically rough surfaces where our model predicts negligible regolith motion, suggesting older, less frequently reworked units. Taken together, these patterns indicate that much of Phobos' surface morphology and spectral heterogeneity can be explained by long-term regolith redistribution driven by the surface acceleration field along RMPs. We provide a 3D morphodynamic atlas of RMPs across Phobos' surface, which will be useful for constraining the geographical provenance of samples to be collected by the MMX spacecraft.

The Aharonov-Bohm (AB) effect remains a cornerstone of fundamental and applied physics. In this work, we utilize the AB caging effect originated from an effective magnetic field induced by multiorbital interactions, creating an all flat band (FB) lattice system. Normally, FB states are known for being compact in space and having a zero tail; therefore, their mobility in a linear environment is generally understood as impossible. We propose a Floquet driving protocol in an all-FB photonic system to fully control the dynamics of localized photonic states. The modulation of the Hamiltonian along the propagation coordinate allows the translation of compact states in the direction of constructive interference, resulting in an effective stroboscopic quantum walk-like effect. We find that the traveling states exist in chiral pairs. We experimentally implement the Floquet driven protocol using femtosecond laser written photonic waveguides and demonstrate directional control of the propagation, determined by the relative phase of the input condition.

We propose a novel muon Moonshot concept for lunar subsurface tomography based on upward-going muons originated from the lunar regolith. Unlike the Earth, the Moon lacks an atmosphere, leaving a dense regolith below and a near-vacuum environment above. Consequently, while most downward-going hadrons are absorbed before decaying, upward-going hadrons escaping the regolith can decay in flight, producing a significant source of lunar muons. These muons are detectable by instruments on the lunar surface or in near-lunar orbit. We perform Monte Carlo simulations to investigate their energy spectra, angular distributions, and integrated fluxes under various theoretical and detector configurations. The results indicate that the lunar muon flux is sensitive to detector altitude under a flat-terrain assumption, demonstrating its potential as a novel non-invasive probe of shallow subsurface voids. We also present case studies on the detection of underground cavities and water resources, with cavity-induced flux variations observable in less than two minutes and weaker water signals distinguishable after about 36 minutes of data collection with a $1~\mathrm{m^2}$ detector, and discuss potential implementations in future lunar missions.

The energy dependence of the complex phases of electron continuum wave functions carries information about electron dynamics. Streaking and attosecond interference experiments (called RABBIT) seek to measure this energy dependence, and therefore, the time delays of ionization. The long-range Coulomb interaction dominates in those experiments, and can obscure the low-energy features of the Wigner time delays that are the object of the measurement. Photodetachment of electrons from negative ions has no long-range Coulomb interaction, and RABBIT and streaking measurements of photodetachment delays have the potential to reveal time delays of up to one femtosecond in low-energy features. We predict the results of such experiments on a particularly interesting polyatomic example, the nitrate anion (NO$_3^-$), for both valence and core electron detachment. We simulate the experiments in these cases and analyze the underlying physics of measurements on polyatomic anions where many electron partial waves contribute and find that the angular dependence of the measured delays generally differs from the Wigner delays. However, we demonstrate that measurements performed for ejection directions close to the polarization of the light sources can directly access the Wigner delays that give a time-dependent window on electron-molecule interactions. A promising experiment involving core photodetachment of NO$_3^-$ with X-rays is proposed.

Channel reciprocity fundamentally limits full-duplex (FD) base stations due to multi-user co-channel interference. We examine the potential of deploying a non-reciprocal dynamic metasurface antenna (NR-DMA) at the base station to overcome this limitation. Our NR-DMA architecture connects a single circulator to three feed ports of a multi-feed DMA with strong mutual coupling (MC) between its seven feeds and 96 1-bit-programmable meta-elements. We model our system with multiport network theory, using experimentally estimated proxy parameters of a fabricated 19-GHz DMA and the measured circulator response. Our NR-DMA's reconfigurability is captured by a diagonal tunable scattering matrix, showing that non-reciprocal DMAs and RISs need not require a "beyond-diagonal" tunable scattering matrix. We jointly optimize the DMA state, analog feed weights, circulator-port assignment, and circulation direction. Our optimized NR-DMA realizes distinct forward and reverse channel responses. In our interference-limited high-SNR case study, the NR-DMA improves the FD sum rate by about 60% over a reciprocal DMA benchmark. Comparisons with proxy objectives and MC-unaware optimization show that end-to-end FD optimization and MC-aware modeling are both essential.

We present a train-resolved SAXS methodology for recovering weak scattering signals from high-repetition-rate XFEL datasets and apply it to aqueous L-cysteine solutions measured at the European XFEL. Independent scale-plus-offset fitting was performed for matched cysteine and water train pairs, followed by subtraction of transmission-matched water–water controls. The 0.5 M dataset reveals a reproducible sign-changing residual SAXS signal that increases with incident XFEL transmission and remains after removal of detector-wide scaling, additive offsets, and matched water–water control residuals. Convergence and block-averaging analyses show that the residual emerges progressively as independent train pairs are accumulated and exhibits uncertainty scaling close to the expected inverse square-root dependence on N. These results establish a statistically robust transmission-dependent residual SAXS contribution whose microscopic origin remains unresolved, while demonstrating that train-resolved observables combined with matched controls can substantially improve sensitivity to weak scattering signals in high-repetition-rate XFEL experiments.

Machine-learning surrogates for computational fluid dynamics (CFD) predict steady flow fields far faster than classical solvers, but emit a single field with no built-in way to know whether to trust it – especially out of distribution. We make the surrogate audit itself against the governing physics: we compute the discretised steady-state Reynolds-averaged (RANS) residual of the prediction and ask what jobs it can do. Our central finding is a clean two-way dissociation: the physics residual is a reliable, backbone-robust trust signal (it tells you where the prediction is wrong) but a poor correction objective (it does not tell you how to fix it). As a trust signal, the residual's per-case rank correlation with field error is consistently positive across three architecturally distinct backbones and a second dataset of laminar bluff bodies; it flags the worst-decile cases with AUROC $\approx 0.9$, and a distribution-free split-conformal layer attains its target coverage. As a correction objective, the residual fails: reducing it does not reduce field error. The monotone-residual acceptance gate built on it, by contrast, does help. Separately, a learned deep-equilibrium corrector trained toward ground truth lowers volume-field error on a state-of-the-art backbone; a controlled ablation that removes the residual input matches this gain, so the improvement comes from the learned correction, not from conditioning on the residual. The contribution is a self-auditing, calibrated trust layer, the residual's two roles (trust signal yes, correction objective no), and the learned correction it accompanies, demonstrated on a competitive surrogate and released as the open-source neuroforge-cfd package.

Toroidal dipole moments arise from poloidal current distributions and form a distinct class of electromagnetic excitations with unique near-field characteristics. Using Lorenz-Mie theory, we show that interference between conventional magnetic and magnetic toroidal dipoles in core-shell nanoparticles produces Fano resonances and pronounced forward-backward scattering asymmetry. By introducing optical gain in the dielectric core, we demonstrate that the toroidal mode can be selectively enhanced, enabling control of near-field confinement and far-field scattering directionality. As the gain varies, we find that the system undergoes a continuous transition from suppressed backscattering to suppressed forward scattering through an intermediate regime of dominant magnetic-dipole radiation. This dipolar scattering pattern is associated with a phase resonance of the magnetic toroidal dipole and a reversal of the poloidal current handedness. These results identify gain-controlled toroidal excitations as a tunable mechanism for directional scattering in nanoscale systems.

We study nested wire media possessing $C_6$ and $C_4$ rotational symmetries whose plasma frequencies can be controlled through breathing deformation. Numerical simulations reveal tunability exceeding $80\%$ and $60\%$ for the considered $C_6$ and $C_4$ breathing geometries, respectively. To describe these structures, we develop an analytical model based on the local field approach within the thin-wire approximation, which confirms the high tunability of the studied wire structures. We also propose an approximation for dense wire media. The developed framework is applicable to the general case of nested wire structures – wire media with an arbitrary parallelogram lattice and multiple wires per unit cell.

We demonstrate that AI-driven program synthesis can autonomously discover fundamental strategies for decomposing unitary matrices in photonic networks. By extending DreamCoder to complex-valued linear algebra, the system generates decomposition programs achieving the minimal $N(N-1)/2$ Mach-Zehnder interferometers, distinct from both Reck and Clements architectures. Learned programs encode dimension-agnostic invariants: strategies discovered for $5 \times 5$ matrices generalize to higher dimensions such as $64 \times 64$. The discovered programs encode interpretable, dimension-agnostic construction rules. These rules generalize across matrix sizes without retraining, demonstrating that autonomous program synthesis can serve as a scalable paradigm for algorithm discovery and the automated design of universal unitary operators. Beyond universal decompositions, the system automatically exploits matrix structure to reduce the interferometer count below the universal theoretical bound. For instance, for Householder matrices, it discovers a dimension-independent rule that requires only $2N-3$ MZIs. This achieves linear, rather than quadratic, scaling and generalizes to arbitrary $N$ without retraining. For matrices obtained from the singular value decomposition of sparse matrices, reductions generally increase with sparsity, reaching up to 38% fewer MZIs than the universal theoretical bound $N(N-1)/2$ at 95% sparsity. These MZI reductions translate directly into practical hardware benefits for scalable photonic implementations. Taken together, the system functions as a single unified engine that discovers both universal decomposition rules and matrix-specific optimizations, without being provided with the structural or analytical properties of the input matrices.

Exoplanet atmosphere characterization heavily relies on molecular spectroscopic data. Despite efforts to obtain comprehensive spectral libraries for the chemical characterization of exoplanet atmospheres, large gaps remain, particularly for larger molecules and higher frequencies at high spectral resolution. One key example is the methane (CH4) optical spectrum. CH4, the simplest hydrocarbon, is a crucial species for exoplanet atmosphere characterization and a possible biosignature. However, until now, high-resolution linelists at optical wavelengths for CH4 have been very challenging to obtain either experimentally or computationally, leaving the high resolution spectrum of CH4 uncharacterised across most of the visible spectrum. This restricts exploration of CH4 absorption in the optical regime, as upcoming instruments such as ELT-ANDES and VLT-RISTRETTO will start probing the atmospheres of ever smaller exoplanets in optical wavelengths. To address this spectroscopic data limitation, we observed Titan's optical spectrum, dominated by CH4 absorption, at the highest spectral resolution to date with VLT-ESPRESSO. From it, we produced an empirical, low-temperature high-resolution (R ~ 190000) linelist of CH4 in optical wavelengths which we present here, with thousands of previously unidentified lines. We employ this CH4 linelist (RRS-2026) to build a template suitable for high resolution cross-correlation spectroscopy (HRCCS) studies, a first for CH4 in optical wavelengths. With this new linelist, we performed the first HRCCS detection of CH4 in the atmospheres of Titan and Jupiter using optical high resolution spectra. This work sets the stage for the search for CH4 in exoplanet atmospheres through HRCCS with current and future ground-based high-resolution optical spectrographs, showcasing how Solar System observations provide useful products for exoplanet research.

We present the first experimental measures of relative dispersion and turbulent diffusion in rapidly-rotating turbulence in the zonostrophic regime, i.e., in the presence of instantaneous and dominant zonal jets. Synthetic Lagrangian trajectories are computed from time-resolved experimental velocity fields, from which we measure relative (two-particle) dispersion. Time-based and separation-based statistics are calculated, including the cumulative inverse separation time (CIST), for which analytical predictions exist in the inertial ranges (direct enstrophy cascade and inverse energy cascade) and in the diffusive regime. These statistics show evidence of a transition from a Richardson regime at scales larger than the energy-injection scale, to a diffusive regime, at scales larger than the transitional scale, the scale at which turbulence becomes anisotropic due to the interaction between turbulent eddies and Rossby waves. The analytical predictions for the CIST allow us to measure the turbulent energy dissipation rate in the Richardson regime, and the turbulent diffusivity in the diffusive regime. Our measurements of diffusivity are broadly consistent with predictions from mixing-length and zonostrophic theories but suggest a shallower dependence on the energy dissipation rate.

Direct numerical simulations (DNS) of fully developed turbulent channel flows at Re_tau = 550 were performed to investigate the corrected Navier-Stokes (CNS) equations. Grounded in the fluid kinematics of Rortex, the CNS abandons the Stokes' isotropic hypothesis and applies the shearing-only constitutive relation by explicitly eliminating the controversial stretching terms in the stress tensor. Comparisons with the DNS data from the traditional Navier-Stokes (TNS) suggest that the CNS inherently rectifies the near-wall momentum transport. The removal of stretching-induced dissipation shifts the inner- and buffer-layer boundaries towards the wall and effectively suppresses the overshoot in the mean velocity profile in TNS. The turbulence statistics demonstrate a multiscale kinetic energy redistribution that intensifies the near-wall production-dissipation cycle. Furthermore, the topological delineation of instantaneous coherent structures, namely the discovery and definition of rotational/non-rotational interface (RNRI) via the velocity gradient tensor (VGT) discriminant (Delta = 0), confirms that the CNS is capable of capturing the highly complex and interwoven vortical structures. Ultimately, the spectral proper orthogonal decomposition (SPOD) unveils and elucidates that the shearing-only mechanisms intrinsically modulate the spatiotemporal energy cascade, promoting denser and more inclined vortices while enhancing turbulence intermittency by fragmenting the coherent packets. Overall, by isolating and detecting the shearing-only mechanism with physics purity, the DNS based on the CNS provides a more refined perception of the intrinsic dynamics of wall-bounded turbulence, offering a more physical soundness model to capture the interactions among the multiscale coherent structures and the improved capability in predicting the wall-bounded turbulence.

This study aims to verify whether combining non-thermal equilibrium atmospheric pressure plasma with benzoyl peroxide (BPO) can enhance the inhibition of bacteria. This work involves not only adjusting the parameters of the plasma device, such as increasing the power supply voltage, modifying the working gas flow rate, as well as incorporating a specific proportion of oxygen to the working gas, but also aims to combine plasma with BPO to inactivate bacteria. An optical emission spectroscopy was utilized to determine the optimal working gas flow rate and oxygen mixing ratio for the experimental setup. Additionally, surface temperature and ultraviolet (UV) emission measurements were also performed to characterize the physical properties of the plasma treatment. Although the precise chemical mechanisms between plasma and BPO have yet to be fully elucidated, bacterial inactivation experiments on Escherichia coli demonstrated that the addition of BPO indeed enhanced the sterilization efficacy of plasma treatment.