Quantum many-body scars (MBS) exhibit weak ergodicity breaking and long-lived coherent dynamics within an otherwise thermal spectrum. We investigate their metrological properties using the quantum Fisher information (QFI), focusing on estimating the amplitude of a weak AC field in the PXP model. We show that the approximately uniform energy spacing of the scar tower enables collective resonant processes when the driving frequency matches integer multiples of the scar gap, resulting in a quadratic-in-time growth of the QFI over an extended time window. We analyze how the connectivity induced by different probe operators shapes sensing performance and demonstrate that staggered magnetization leads to a more favorable growth of the QFI with system size than homogeneous magnetization. Through frequency scanning and finite-size analysis, we characterize the scaling of the QFI with the number of particles. Finally, we develop a single-tower approximation under resonant driving, deriving a compact analytical expression that captures the time dependence and system-size scaling of the QFI. Our results establish how to leverage structured non-ergodic dynamics in quantum sensing protocols.

Fault-tolerant logical operations are fundamental for scalable quantum computation. Here, we report the experimental realization of lattice-surgery operations between a pair of distance-three surface-code logical qubits on a planar superconducting processor. During repeated syndrome extraction cycles, the logical qubits exhibit per-cycle error rates of $0.0365(2)$ and $0.0282(1)$, respectively, after leakage events are rejected. By leveraging joint initialization and lattice splitting, we deterministically prepare a logical Bell state, confirming genuine bipartite entanglement via the error-corrected logical state fidelity. We further execute a two-qubit Deutsch-Jozsa algorithm at the logical level to demonstrate algorithmic utility in a fault-tolerant framework. Finally, to achieve universal control, we implement magic-state injection and gate teleportation to realize continuous non-Clifford rotations about the logical $X$ axis. For the logical $R_{X}(π/4)$ gate, we achieve a logical gate fidelity of $0.943_{-9}^{+10}$ conditioned on the absence of detected errors. These results establish lattice surgery as a practical and versatile paradigm for logical computation in near-term surface-code architectures, representing a critical milestone toward scalable fault-tolerant quantum advantage in superconducting circuits.

We introduce the quantum vector Hopfield network, in which patterns are formed by orientations of quantum vector spins; quantum dynamics arise intrinsically from the non-commutativity of the spin operators. We derive the equations of state and the phase diagrams for this network as well as its classical counterpart. We find that quantum fluctuations, surprisingly, stabilize the stored patterns. Both the critical retrieval temperature and the target pattern overlap are enhanced relative to the classical network. Additionally, we find that this enhancement grows with pattern loading up to network capacity. We interpret this effect as an analog of quantum order-by-disorder, a mechanism by which quantum fluctuations promote the formation of ordered phases. These findings offer a new route to quantum-enhanced associative memory.

Quantum Darwinism extends the decoherence formalism to explain how classicality and objectivity emerge from quantum mechanics. However, existing approaches often capture only partial aspects of objectivity, leading to its mischaracterization and making it difficult to pin down precisely. By connecting quantum Darwinism to operator algebra quantum error correction, we show that the emergence of objectivity can be identified with the algebraic local recoverability of quantum codes. Applying this algebraic framework to stabilizer codes, we show that it yields a far more precise characterization of classicality and redundancy, unifies the traditional measures of objectivity, enables efficient classification via coding-theoretic tools, and supports large-scale Clifford simulations of decoherence dynamics.

We investigate a nonlinear extension of the Madelung transformation based on a hyperbolic phase--amplitude coupling of the form \[ Ψ= R e^{\imathθ\coth R}, \] where \(R\) is a real amplitude field and \(θ\) is an auxiliary phase coordinate governed by Schrödinger's equation. In contrast to the conventional polar decomposition, this construction imposes a singular hyperbolic relation between amplitude and phase, thereby endowing the Bohmian or hydrodynamic description with an intrinsically geometric structure. We show that the associated velocity field acquires a density-gradient contribution, producing generalized continuity equations and modified quantum force terms. When interpreted as a complex macroscopic order parameter, this generalized phase structure leads to modified superconducting electrodynamics; in particular, the London equations acquire additional contributions that render the Meissner response sensitive to spatial density gradients. The proposed framework is motivated by broader developments involving complex group velocities, dissipative wave propagation, and amplitude-sensitive transport in quantum systems.

Quantum encrypted cloning shows that an unknown quantum state can be distributed into multiple encrypted copies without contradicting the no-cloning theorem: each copy is unusable on its own, but can be redeemed together with a suitable quantum key. Recent work has related canonical encrypted-cloning protocols to particular forms of quantum secret sharing. Here we take the converse perspective: instead of mapping a given encrypted-cloning protocol into QSS, we use QSS access structures as a design library from which encrypted-cloning schemes can be extracted. The criterion is access-structural. A QSS scheme supports a quantum encrypted-cloning structure whenever it contains a family of qualified sets with a non-qualified common intersection. The common subsystem is interpreted as the key, while the non-common parts are interpreted as encrypted clones relative to that key. Thus quantum encrypted cloning does not require a new notion of recoverability beyond QSS; what changes is the operational reading of QSS constituents as a mechanism for delayed and alternative redemption opportunities. This viewpoint separates redemption from perfect secrecy. Perfect QSS yields encrypted-cloning schemes with forbidden non-qualified subsystems, whereas ramp QSS naturally allows intermediate, partially informative non-redeeming subsystems. The resulting framework broadens quantum encrypted cloning from a specific protocol to a general access-structure primitive. We illustrate the extraction principle with threshold-like, ramp, hierarchical, and compartmented architectures, showing how encrypted clones may be symmetric or asymmetric, individual or composite, perfectly hidden or leaky. Equivalently, these constructions can be viewed as overlapping erasure-recovery regions of an isometric quantum code. This establishes secret sharing as a systematic design language for encrypted quantum redundancy.

Quantum metasurfaces comprised of subwavelength atomic arrays emerged as a promising platform for enhanced atom-photon interaction. However, realizing such a system with solid-state emitters has been considered impractical due to strong inhomogeneous broadening, which was expected to suppress the photon-mediated interactions that underpin collective emission. Here we report the observation of collective emission from subwavelength arrays of silicon-vacancy centres in diamond -- solid-state emitters whose inhomogeneous broadening exceeds the natural linewidth by two orders of magnitude -- demonstrating that collective effects such as resonance shifts, modified decay rates and directional coherent emission survive this disorder. A crucial enabling element is the implantation of a high density of silicon ions at each array site. This creates so-called superatoms, local ensembles that probabilistically achieve frequency matching across the array and enhance the collective response. We support our observations with a theoretical analysis explaining the mechanisms that preserve the collective effects even in the presence of inhomogeneity. These observations have direct implications for the realization of subwavelength arrays in any solid-state system, paving the way for quantum-emitter metasurfaces that are naturally integrated into nanophotonic environments.

Optical poling is a well-established technique for inducing χ^{(2)} nonlinearity, yet its impact on silica's molecular structure remains unexplored. Here, we report the first direct observation of molecular restructuring in large-core graded-index multimode fibers (MMFs) induced by optical poling, transforming the silica tetrahedral ring network. Through coherent light beating, this process converts large rings of more than four SiO_4 tetrahedra into smaller ones, altering both linear and nonlinear optical susceptibilities. Contrary to the assumption that poling efficiency stems solely from charge displacement, we show that structural modifications dominate, leading to record enhancements in third-order nonlinear processes, including geometric parametric instabilities (GPIs) and Kerr self-cleaning, despite a low modification of the Kerr coefficient. High-energy poling acts as an in situ annealing process, dynamically modulating the refractive index for unprecedented spatiotemporal light control. These findings provide fundamental insights into silica's molecular dynamics under intense optical fields and open avenues for ultra-efficient nonlinear optical devices, enabling next-generation fiber-based photonics for high-power lasers, broadband light generation, and all-optical signal processing.

This article proposes an analytical method to address the slow convergence of electronic structure calculations caused by the inability of finite one-particle basis sets to describe the electron-electron cusp. An equivalence is made between a calculation using a finite basis set with the physical Coulomb interaction and a calculation using a complete basis set with a model interaction (specifically, the error-function screened Coulomb potential characterized by a range-separation parameter $μ$). By leveraging the adiabatic connection formalism, a simple, parameter-free correction formula is derived. It depends only on the on-top pair density and a locally defined range-separation parameter ($μ$) derived from the basis set itself. This `adiabatic connection based basis set error correction' (ABC) is derived from the asymptotic expansion of the wave function at large $μ$ for small inter-electronic distances. Therefore it is applicable to both ground and excited states without the restriction imposed by the Hohenberg-Kohn theorem. Numerical tests illustrate that the method achieves chemical accuracy using smaller basis sets than typically required.

This study investigates a minimal mechanism through which local mobility heterogeneity produces global reconfiguration in structured agent-based systems. Agents move in a multi-attractor landscape, where a small fraction exhibits higher-mobility exploratory dynamics while the remainder remain locally constrained. By comparing random-walk exploration, interface-sensitive dynamics, novelty-biased exploration, and a flat-landscape control, I identify the conditions under which large-scale connectivity emerges. As the fraction of exploratory agents increases, the system transitions from a fragmented regime to an increasingly connected transition network. Event-level analysis shows that configurational switching is strongly localized near inter-attractor boundaries, indicating that interfaces act as critical gateways through which transitions occur. These localized events accumulate over time, progressively integrating the landscape. Importantly, the core effect persists under minimal random-walk exploration, demonstrating that neither optimization nor goal-directed behavior is required. By contrast, when landscape structure is removed, connectivity becomes operationally trivial and the boundary-mediated mechanism disappears. The results show that large-scale reconfiguration emerges from the interaction between mobility heterogeneity and spatial constraints. More broadly, they suggest a minimal generative principle for global connectivity in agent-based systems, highlighting the role of boundaries as mediators of emergent connectivity.

Bright squeezed vacuum (BSV) light has a vanishing mean optical electric field yet can strongly enhance strong-field nonlinear responses beyond the conventional semiclassical paradigm. Here we examine this scenario in the light-matter strong-coupling regime by investigating resonant multiphoton ionization of atoms driven by BSV, using a fully quantum treatment of both the electron and the field. Our results show that the photoelectron energy spectrum exhibits an anomalous Autler-Townes splitting whose magnitude grows with the Above-threshold-ionization (ATI) order, rather than remaining essentially ATI-order independent as in the case of coherent driving. This behavior reflects a general scaling with the number of absorbed photons and originates from the broad photon-number fluctuations of the driving field together with the resulting electron-field entanglement. We further show that the BSV-induced enhancement of ionization yields evolves with intensity, crossing over from the $g^{(p+1)}$ limit to the $g^{(p)}$ limit as Rabi oscillations become established. These results identify a quantum regime of strong-field ionization governed by the interplay of photon statistics, nonlinear transitions, strong coupling, and nonseparable light-matter dynamics.

Green's function-based downfolding methods construct effective Hamiltonians of reduced dimension that capture dynamical correlations of an electronic environment through effective potentials acting on the active space only. Using methods based on the constrained random phase approximation (cRPA) and moment RPA (mRPA), we construct static effective Hamiltonians that include screening through the environment. We derive expressions for the energy contribution from the environment and for the effective one- and two-body terms, taking into account double-counting corrections. cRPA requires additional consideration due to its frequency dependence, while mRPA provides a static Hamiltonian by construction. For the ground state energy of benzene and bond dissociation curves, we discuss the differences and similarities between the different flavors of RPA-based screening. We show that downfolding using cRPA describes both dynamical and strong correlation well, while mRPA and cRPA restricted to screening the particle-hole matrix elements can fail to describe bond dissociation due to a dominating dynamical correlation term. In the static limit, these two methods are shown to be almost indistinguishable.

This paper presents a detective scaffolding framework -- a three-phase instructional sequence (Hypothesis Activation -> Evidence Structuring -> Causal Integration) in which engineering students investigate a realistic industrial defect scenario using staged in-class polls as designed evidence probes. Unlike conventional uses of student response systems for engagement, the framework positions each poll as an Evidence-Centred Design instrument targeting a specific reasoning capability. In the primary implementation, 80 Year~3 polymer engineering students progressed from prior-knowledge-driven misconception (71% attributing defects to temperature) to complete root-cause convergence (100\% identifying humidity; Fisher's exact test, $p < .001$) across four sequenced prompts within a single 90-minute lecture slot. A dual-accuracy analysis revealed that at one intermediate stage, textbook-correct and analytically valid responses diverged, illustrating why conventional scoring can misrepresent reasoning quality. In a transferability study, 26 Year~12 students with no engineering background achieved identical root-cause identification rates across two adapted scenarios, with significant gains in data-analysis confidence and AI explanation ability. The results suggest that the pedagogical structure, rather than disciplinary content, drives the convergence effect, implying portability across disciplines and educational levels.

We summarise Sensor Quality Control (SQC) results of non-irradiated silicon sensors for the CMS HGCAL detector, as well as the first detailed annealing campaign with a wafer-scale 120\,\textmu m (Epitaxial) sensor exposed to \(2\times10^{15}\)\,\si{n_{eq}/cm^2} at the Rhode Island Nuclear Science Center (RINSC). For the non-irradiated sensors, we present an overview of the QC workflow developed for HGCAL, including automated handling of vendor data, validation of electrical measurements, and cross-checking of wafer-level characteristics. The study investigates, for the first time, the isothermal annealing behaviour at 60\,\si{\celsius} after annealing periods ranging from 10 to 5000 minutes. Hamburg-model parameters for effective doping concentration changes with annealing time, extracted from full-sensor data, are presented. The post-irradiation behaviour of sensors with hot regions in the pre-irradiation leakage current measurements, as well as epitaxial sensors with stacking faults in individual cells, is also investigated.

Polymer self-consistent field theory (SCFT) has recently been established as a promising alternative framework to Kohn-Sham density functional theory (KS-DFT) for modeling quantum many-body systems. It uses real-valued propagators instead of orbitals, simplifying the self-consistent numerical solution. However, SCFT suffers from inaccuracies in heavy-element systems due to the approximate treatment of the Pauli potential, particularly the use of a constant repulsion strength parameter. In this work, we address this central limitation by introducing a Z-dependent Pauli potential that improves agreement with Hartree-Fock (HF) results. Furthermore, we advance SCFT implementation by employing B-spline basis functions-highly localized, piecewise-polynomial functions widely used in atomic structure theory. We demonstrate that B-splines provide a flexible and efficient representation of electronic structure, and present results for atomic binding energies from hydrogen to xenon. Comparisons with HF theory and prior SCFT calculations using Gaussian basis sets highlight the improved accuracy achieved with the Z-dependent potential.

We theoretically investigate circular dichroism in the ion yield following $1+1+1$ ionization of 3-methylcyclopentanone using femtosecond linearly chirped laser pulses, inspired by recent experiments by Das et al. [Phys. Chem. Chem. Phys. 27, 8043 (2025)]. To this end, we numerically solve the time-dependent Schrödinger equation and evaluate the total population in the Rydberg states at the end of the second absorption step. The A-band transition in the first absorption step is treated using state-of-the-art quantum-chemical calculations, whereas the second absorption step is described via an effective model. Within our framework, we identify the interplay between the first and second absorption step as the key explanation for the experimentally observed chirp dependence of the anisotropy. By elucidating this mechanism for the chirp-enhanced signal, our findings contribute towards the development of improved control schemes for chiral molecules.

Free-space optical systems are promising candidates for high performance computing and have been particularly successful in the implementation of large-scale convolutions. Convolutions are the key operation in convolutional layers, which are used extensively in modern neural networks, especially in the context of image/video processing and generation. These optical accelerators have demonstrated remarkable performance in both processing rates and energy efficiency. Prior approaches have primarily demonstrated convolutions from a single input channel to one or more output channels. We extend these methods to perform true multi-channel convolutions, where multiple input channels are convolved with their own sets of convolutional kernels onto output channels. We simulate this approach using both ray-tracing and angular spectrum propagation and find the approach is highly-scalable. We then experimentally implement a proof-of-concept prototype to demonstrate multi-channel free-space optical convolutions.

We demonstrate distributed acoustic sensing on deployed buried cable leveraging laser frequency stabilization and probing code optimization. Our results confirm the capability to accurately localize weak events with high resolution and sensitivity over 80 km.

Virtual accelerators and digital twins are increasingly essential tools for accelerator operations, controls development and verification, and model-based optimization. However, current implementations are often tightly coupled to specific simulation codes, facilities, and applications, resulting in fragmented, ad hoc solutions that are difficult to reuse or extend. To address this, we expand the LUME Python package to include standardized implementation and deployment of virtual accelerators and digital twins across heterogeneous simulation backends and control system interfaces. At the core of this change is the introduction of LUMEModel abstraction, which defines a fixed, simulator-agnostic API and a variable system that encodes metadata such as units and data types/validation. This design enables standardized interaction with physics-based simulators, surrogate models, and differentiable simulations, while supporting both Python-native workflows and IOC-based operation via EPICS using the lume-pva package. Facility- and simulator-specific details are encapsulated through extensible transformer layers, allowing consistent control-system semantics to be mapped onto diverse simulation engines. We describe the LUMEModel architecture, variable system, and package ecosystem, and present representative use cases including model interchangeability, staged and chained simulators, and continuous integration testing. This work will make implementing and using virtual accelerators easier and more flexible.

Temporal interfaces, defined by abrupt changes in material properties, break temporal translational symmetry and enable wave phenomena fundamentally different from those at spatial interfaces. Unlike spatial scattering, temporal scattering preserves momentum rather than energy, leading to instantaneous frequency shifts governed by the dispersion relations on either side of the interface. Existing studies in elastic media have mainly considered non-resonant materials, and allow only one-to-one frequency conversion across temporal interfaces. Here, we propose temporal interfaces formed by the sudden activation of local resonators in elastic metamaterials, which induces a transition from non-resonant to resonant dispersion. We demonstrate that such interfaces can induce frequency splitting among scattered waves and elucidate how the scattered-wave amplitudes are governed by the weighted modal correlation coefficients and impedances. Moreover, a novel temporal evanescent mode, characterized by spatial stationarity and temporal decay is demonstrated after the interface, which is well explained by the negative effective modulus evaluated at imaginary frequencies. These findings establish a foundational understanding of wave dynamics at temporal interfaces involving resonant materials, open new opportunities for wave manipulation in time-varying solids.

Two analytical models for sizing the toroidal field coils and central solenoid of a tokamak are developed within the D0FUS system code: a pedagogical thin-cylinder model and a refined thick-cylinder and winding packs model. The refined model shows good agreement with six reference machines and the MADE magnet design code. When the high-field design space is explored for DEMO-class power plants (2 GW of fusion power, Q = 40, tplateau = 2 h), pushing the peak field at the Toroidal Field (TF) coil conductor up to Bmax = 20 T, the radial build emerges as the dominant constraint: in fact, in the baseline wedging/316L configuration, no viable design can be found beyond 20 T, making alternative strategies necessary. The primary levers identified are high-strength steels (e.g CHSN01), alternative mechanical architectures (bucking, plug), and reductions of the effective Central Solenoid (CS) flux demand (for example through auxiliary heating during ramp-up), each carrying an impact of the same order of magnitude on the minimum feasible major radius. Secondary optimisations (conductor shape, radial grading) are shown to provide additional but more modest gains. When all favourable levers are combined (CHSN01, bucking, etc.), compact machines (R0 < 4 m) appear feasible. This suggests that, provided one accepts the associated risks of combining new approaches (CHSN01, bucking, etc.), high-temperature superconductors could unlock the path to compact electricity generating tokamaks.

Clinical observations of dry eyes reveal that tear film breakup is associated with spatial variations in corneal wettability arising from non-uniform mucin coverage. Motivated by these observations, we develop a thin-film model to investigate the influence of heterogeneous wettability on tear film stability. Heterogeneity in mucin coverage is incorporated through variations in the Hamaker constant and slip length along the corneal surface. Two representative forms of spatial heterogeneity are considered: a periodic step variation representing sharply localised mucin-deficient patches and a smoothly varying sinusoidal distribution representing gradual changes in glycocalyx. The steady states are obtained by a balance between capillary and van der Waals forces. A linear stability framework based on Floquet-Bloch theory and a discretised eigenvalue approach is developed to account for the periodic coefficients in the linearised equations. We show that heterogeneous wettability induces coupling between perturbation modes. The most unstable wavenumber and the maximum growth rate decrease with increasing mucin coverage fraction. However, both increase with increasing Hamaker constant contrast between mucin-rich and mucin-deficient regions. Nonlinear simulations reveal that rupture preferentially localises within mucin-deficient regions irrespective of the initial film thickness. The rupture location is governed by the spatial distribution of disjoining pressure rather than the initial perturbation. The predicted rupture dynamics are consistent with clinical observations where rupture location is invariant and the rupture times obtained from the model are in good agreement with clinically reported values. These findings demonstrate that spatial heterogeneity in wettability plays a decisive role in tear film instability and must be incorporated in tear film dynamics models.

Optimal conditions for unidirectional coupling in quasi-phase-matched non-Hermitian systems are analyzed for both autonomous and externally driven configurations. The quasi-phase-matched coupling mechanism is due to periodic modulation of the real and imaginary parts of the coupling interface, which results in unequal coupling coefficients between interacting waves. The conventional parity-time (PT) symmetry theory suggests that the strongest unidirectionality should occur exactly at the exceptional point (EP). We show that this expectation is generally incorrect, as the optimum is shifted away from the EP depending on the detuning from exact quasi-phase-matching resonance. We formulate a unified two-mode description for autonomous and driven systems, and derive the corresponding normal forms near the shifted singularities associated with the EPs.

Implicit structural modeling can support understanding subsurface spatial configurations, revealing patterns of geological evolution, and enabling quantitative simulation of geological processes, thereby offering substantial scientific and engineering value. Conventional approaches formulate it as an optimization problem or framework interpolation to fit a continuous scalar field, whereas machine learning methods typically adopt discriminative regression to directly predict implicit models. However, in complex scenarios involving fault intersections, branching, and thrust nappes, these methods still struggle to maintain topological consistency and kinematic plausibility. In this work, we develop an implicit structural modeling approach based on diffusion models. We construct a set of training data through a simulation based synthesis pipeline and design a dedicated encoder for conditional injection, allowing the conditional branch to converge rapidly while effectively reinforcing the input conditional priors throughout the diffusion process, thereby more stably propagating structural constraints. We then inject these conditional features into a backbone network pretrained on large scale natural images to enable conditional training of the diffusion model. Although our synthetic data include only a relatively stylized normal fault system, experiments demonstrate strong generalization, enabling the model to effectively handle diverse complex structural types such as strike slip faults and intricate flower fault systems. More importantly, even in challenging thrust nappe settings where the scalar field becomes non monotonic and exhibits abrupt depth discontinuities, the model can still generate reliable implicit structural models.

Laser plasma accelerators (LPAs) are a promising platform for compact radiation sources. For a wide range of applications, including radiotherapy, ultrafast electron diffraction and time-resolved imaging, stable operation at high repetition rates is essential in order to deliver competitive average particle flux. Here we demonstrate the first LPA driven by an industrial-grade ytterbium-doped yttrium aluminium garnet (Yb:YAG) laser, designed for high-average-power operation. The picosecond laser pulses are post-compressed in a multi-pass cell to 50 fs duration and used to drive the interaction. The electron accelerator is operated in burst mode, at repetition rates tuneable from 0.625 to 6.25 kHz, representing a substantial increase compared to the state-of-the-art. Across this range, the electron beam properties remain unchanged, with average charges of 10-12 pC per shot, divergences of 50-70 mrad, and Maxwellian-like spectra extending to a few MeV. Numerical simulations capture the key features of the experimental observations and indicate acceleration in the self-modulated regime, enabled by relativistic self-focusing in near-critical-density plasma. Combining industrial high-average-power laser technology with plasma-based acceleration, these results represent a key step toward scalable, compact high-repetition-rate electron sources for medical, imaging and industrial applications.

The optical transfer matrix formalism is used to describe global set-ups incorporating a plenoptic camera. Analytical relations that give the effective resolution, depth of field, disparity and optimum patch size for image reconstruction are established versus the optical parameters of any global arrangement. The potentiality of this formulation is illustrated analyzing experimental results obtained in astigmatic cylindrical imaging conditions.

Farassat's Formulations 1 and 1A have been extensively employed for propeller noise prediction. However, in the derivation of Formulation 1A from Formulation 1, the contribution associated with the temporal variation of the direction of the unsteady force is omitted, appearing mathematically as the temporal derivative of the local surface normal vector. Through rigorous mathematical derivation, this study demonstrates that the omitted term constitutes an indispensable component of the acoustic source representation. Accordingly, a Modified Formulation 1A is proposed by explicitly retaining the normal vector temporal derivative term in the time-domain formulation. Far-field acoustic predictions for propellers are performed to evaluate the proposed formulation, and the results confirm both its theoretical consistency and predictive capability.

Scattering exceptional points (EPs) are non-Hermitian degeneracies where the eigenvalues and eigenvectors of scattering matrices coalesce, enabling many intriguing phenomena in optical systems. Higher-order scattering EPs are particularly notable for their ultrasensitive response to perturbations, yet achieving flexible, arbitrary-order control remains challenging. Here, we propose a configurable non-Hermitian zero-index material (ZIM) network that enables arbitrary-order scattering EPs, as rigorously proved theoretically and validated numerically. Specifically, we show that in an N-port non-Hermitian ZIM network embedded with loss/gain dopants, the maximum achievable EP order is N, and the order can be flexibly tuned from 2 to N or completely eliminated by adjusting the dopants. Furthermore, we compare conventional coherent perfect absorption with absorbing EPs of different orders. Although both achieve perfect absorption of all incident waves, a second-order EP already outperforms coherent perfect absorption, and higher-order EPs provide further power-law enhancement. These findings establish a pathway toward realizing arbitrary-order EPs in open scattering systems, holding significant promise for advanced sensing applications.

Fusion reactivity is enhanced in the vicinity of strongly sheared flow due to the tendency of fast ions near the Gamow peak to travel long distances between collisions, thereby sometimes crossing gradients in the background flow and attaining a velocity boost relative to the thermal background. This ``shear flow reactivity enhancement effect'' (SFRE) allows turbulent kinetic energy on fine spatial scales to contribute to fusion reactivity before thermalizing, which, remarkably, enables ignition of some inertial confinement fusion (ICF) hot spots under conditions where fully thermalized plasma would fail to ignite. The size of the SFRE is a consequence of the dramatic scale separations distinguishing thermal ions, which govern fluid quantities, and fast ions, which govern fusion reactivity. It is demonstrated in this work that, as the Gamow energy increases relative to the thermal energy, the SFRE in unmagnetized plasma becomes asymptotically large compared to hydrodynamic effects such as viscous dissipation. An asymptotic formula is derived in this limit, quantifying the SFRE for reactants of disparate masses and charge states.

We give a variational formulation of the continuous adjoint Kutta condition for two-dimensional subcritical potential flow, with emphasis on the Kutta condition and the role of the wake. We show that the adjoint Kutta condition can be imposed by a penalty term evaluated at the trailing edge, with the corresponding Lagrange multiplier determined by stationarity of the Lagrangian with respect to circulation, and that a wake treatment is not required. Some of the implications of these results for adjoint consistency are also briefly discussed.