Computational Physics · Cross-listed from cond-mat.str-el
Graph neural network force fields for adiabatic dynamics of lattice Hamiltonians
Yunhao Fan and Gia-Wei Chern
Scalable and
symmetry-consistent force-field models are essential for extending
quantum-accurate simulations to large spatiotemporal scales. While descriptor-based neural networks can incorporate
lattice symmetries through carefully engineered features, we show that graph neural networks (GNNs) provide a conceptually simpler and more unified alternative in which discrete
lattice translation and point-group
symmetries are enforced directly through local message passing and weight sharing. We develop a GNN-based force-field framework for the adiabatic dynamics of
lattice Hamiltonians and demonstrate it for the semiclassical Holstein model. Trained on exact-diagonalization data, the GNN achieves high force accuracy, strict linear scaling with system size, and direct transferability to large
lattices. Enabled by this scalability, we perform large-scale Langevin simulations of charge-density-wave ordering following thermal quenches, revealing dynamical scaling and anomalously slow sub–Allen–Cahn coarsening. These results establish GNNs as an elegant and efficient architecture for
symmetry-aware, large-scale dynamical simulations of correlated
lattice systems.
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Computational Physics · Cross-listed from cond-mat.str-el
Tensor-network methodology for real-space super-moiré excitons
Anouar Moustaj, Yitao Sun, Tiago V. C. Antão et al. (+2 more)
Computing excitonic spectra in quasicrystal and super-moiré systems constitutes a formidable challenge due to the exceptional size of the excitonic
Hilbert space. Here, we demonstrate a tensor-network method for the real-space Bethe-Salpeter
Hamiltonian, allowing us to access the spectra of an excitonic $10^{18}$-dimensional
Hamiltonian, and enabling the direct computation of bound-
exciton spectral functions for systems exceeding one billion
lattice sites, several orders of magnitude beyond the capabilities of conventional approaches. Our method combines a tensor-network encoding of the real-space Bethe-Salpeter
Hamiltonian with a Chebyshev tensor network
algorithm. This strategy bypasses explicit storage of the
Hamiltonian while preserving full real-space resolution across widely different length scales. We demonstrate our methodology for one- and two-dimensional super-moiré systems, achieving the simultaneous resolution of atomistic and mesoscopic structures in the excitonic spectra in billion-size systems, showing
exciton miniband formation and moiré-induced spatial confinement. Our results establish a real-space methodology enabling the simulation of excitonic physics in large-scale quasicrystal and super-moiré
quantum matter.
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All authors Anouar Moustaj, Yitao Sun, Tiago V. C. Antão, Lumen Eek, Jose L. Lado
Plasma Physics
A theoretical model for quantifying the imprinting sensitivity of direct-drive inertial confinement fusion implosions
Dongxue Liu, Jiaqin Dong, Yunxing Liu et al. (+5 more)
To quantify the sensitivity of diverse implosion designs to
laser imprinting, we developed an equivalent perturbation model that maps
laser imprinting as the initial target surface perturbation. By incorporating imperfections in target fabrication and thermal smoothing in the
plasma, the model shows a reduced implosion sensitivity to
laser imprinting, extending the analysis beyond
geometric irradiation. The imprinting sensitivity threshold is defined as $\frac{\delta h_{\text{proxy}}}{\delta h_{\text{tar}}(0)} = 0.1$, where $\delta h_{\text{proxy}}$ is the imprinting amplitude and $\delta h_{\text{tar}}(0)$ is the initial target perturbation amplitude. Radiation-hydrodynamics simulations confirm that when $\frac{\delta h_{\text{proxy}}}{\delta h_{\text{tar}(0)}} \leq 0.1$, variations in nonlinear onset time and adiabat remain within 12% of that with $\delta h_{\text{tar}}(0)$ alone. Moreover, the imprinting sensitivity is supported by OMEGA experiments. Overall, for linear perturbations of medium-to-high modes in direct-drive, the model enhances our physical understanding of how
laser and target perturbations evolve and serves as a simplified tool to optimize implosion performance.
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All authors Dongxue Liu, Jiaqin Dong, Yunxing Liu, Zhiyu He, Wei Wang, Yuqiu Gu, Xiuguang Huang, Jian Zheng
Fluid Dynamics
Hybrid ROM-PINN Framework for Closure Modeling in Convection-Dominated Systems
Ferhat Kaya, Birgul Koc, Atakan Aygun et al. (+2 more)
Reduced-order models (ROMs) have become an essential tool for reducing the computational cost of fluid flow simulations. While standard ROMs can efficiently approximate laminar flows, their accuracy often suffers in convection-dominated regimes due to the truncation of dynamically important modes. To account for the influence of unresolved scales, ROM closure models are commonly introduced. Classical closure strategies are typically based on phenomenological arguments or analogies with large eddy simulation (LES), often formulated within a variational multiscale (VMS) framework, in which the resolved and unresolved scales are explicitly separated and their interactions are systematically modeled. More recently, advances in data-driven modeling and machine learning have opened new opportunities to construct ROM closures that are both more accurate and more consistent with the underlying physics. In this work, we develop a new ROM closure that combines machine learning with physics-based modeling principles. The closure term is derived within a VMS framework, where the reduced solution space is decomposed into resolved and unresolved components. This VMS-derived closure term is then modeled using PhysicsInformed Neural Networks (PINNs) and incorporated into a newly constructed C-PINN-ROM. The resulting closure leverages high-fidelity data while enforcing physical constraints imposed by the reduced-order equations, thereby ensuring consistency with the underlying dynamics and enhanced robustness in convection-dominated regimes. Through this PINN-based framework, we demonstrate how physics-informed machine learning can substantially improve the accuracy and robustness of ROMs, effectively bridging classical multiscale closure modeling with state-of-the-art data-driven methodologies.
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All authors Ferhat Kaya, Birgul Koc, Atakan Aygun, Onur Ata, Ali Karakus
Medical Physics
Assessing Hemodynamic Impact of Tissue-Engineered Vascular Graft Displacement: Combining Postoperative in vivo Results and Computational Modeling to Improve Surgical Planning
Seda Aslan, Enze Chen, Miya Mese-Jones et al. (+11 more)
Tissue-engineered vascular grafts (TEVG) have shown promise in advancing vascular reconstructions. However, precise in vivo implantation is challenging, and it is unclear how deviations in location and size affect hemodynamics. This study aims to compare preoperative designs and postoperative anatomies of TEVG in an in vivo study to evaluate discrepancies and investigate the impact of graft displacement and size on hemodynamics by virtually simulating implantation scenarios that are informed by in vivo postoperative results. Designed and postoperative geometries of four porcine aortas were compared to measure the mismatch in implantation location and graft shape. These results informed a virtual TEVG implantation study. TEVG location, orientation, and size were varied to investigate the effects on the final aorta shape and hemodynamics. Anastomosis of TEVG was simulated using finite element modeling. Key hemodynamic metrics were obtained from virtual implantations and actual postoperative anatomies using computational fluid dynamics. Our in vivo study showed that TEVGs can experience up to 6.9 mm displacement and a 38 degree rotational shift post-implantation, leading to discrepancies in pressure drop (2.5 mmHg, 50%) and time-averaged wall shear stress (7.2 Pa, 72%) compared to predictions. Virtual anastomosis simulations improved aortic shape predictions by 27.5%. Our results highlight the sensitivity of key hemodynamic metrics to graft implantation location and size mismatch. By quantifying displacement ranges and their impacts during surgery, surgeons can make informed decisions.
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All authors Seda Aslan, Enze Chen, Miya Mese-Jones, Jacqueline Contento, Hidenori Hayashi, Keigo Kawaji, Joey Huddle, Jed Johnson, Yue-Hin Loke, Mark Fuge, Laura Olivieri, Thao D Nguyen, Narutoshi Hibino, Axel Krieger
Accelerator Physics
Radiation safety challenges in plasma accelerators
S. Bohlen, M. Kirchen, T. Liang et al. (+9 more)
Plasma accelerators are rapidly evolving toward user-relevant machines with increasing repetition rates, particle energies and average beam powers. Despite their compact size, the operational characteristics of
plasma accelerators are comparable to those of
radio-frequency linacs, involving the continuous generation and dumping of electron bunches. However, beam properties and loss patterns can differ substantially from those of conventional accelerators, leading to radiation safety considerations dominated by high peak charges and distributed beam losses relevant for both personnel protection and machine integrity. Using established scaling laws, we show that significant dose rates already occur at electron energies of several MeV, underscoring the relevance of radiation protection even for comparatively low-energy
plasma accelerators. Based on a combination of Monte Carlo and particle-in-
cell simulations, supported by radiation measurements from
plasma accelerator experiments at DESY, we analyze typical radiation fields with a particular focus on radiation generated close to the
plasma source. These findings highlight the need for dedicated shielding and beam-dump concepts tailored to
plasma accelerators, especially in view of increasing average beam powers and future application-oriented operation.
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All authors S. Bohlen, M. Kirchen, T. Liang, A. Leuschner, A. R. Maier, A. Martinez de la Ossa, E. Panofski, K. Schubert, M. Thévenet, P. A. Walker, I-L. Yeh, S. Zander
Fluid Dynamics · Cross-listed from math.NA
Asymptotic Analysis of Shallow Water Moment Equations
Mieke Daemen, Julio Careaga, Zhenning Cai et al. (+1 more)
The Shallow Water Moment Equations (SWME) are an extension of the Shallow Water Equations (SWE) for improved modelling of free-surface flows. In contrast to the SWE, the SWME incorporate vertical velocity profile information. The SWME framework approximates vertical velocity profiles using a
polynomial expansion with Legendre
polynomials and
polynomial coefficients, also called moment variables. The SWME have an increased number of variables that must always be incorporated, even when the flow approaches a viscous slip
equilibrium state that could be characterised by vanishing moment variables. To reduce the complexity of the SWME in cases proximate to this
equilibrium, we conduct an asymptotic analysis of the SWME. This yields the closed form Reduced Shallow Water Moment Equations (RSWME) for deviations from the
equilibrium. The RSWME have fewer variables, compared to the SWME. The hyperbolicity of the RSWME is analysed. Numerical tests include a wave with a sharp height gradient, a smoother height gradient and a square root velocity profile. The numerical tests demonstrate that the RSWME reduce computational cost up to 77% compared to the SWME and improves accuracy up to 88% over the SWE.
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All authors Mieke Daemen, Julio Careaga, Zhenning Cai, Julian Koellermeier
Chemical Physics
A Relationship between the Molecular Parity-Violation Energy and the Electronic Chirality Measure
Juan J. Aucar, Alessandro Stroppa and Gustavo A. Aucar
When the weak-forces producing parity-violating effects are taken into account, there is a tiny energy difference between the total electronic energies of two enantiomers ($\Delta E_{PV}$), which might be the key to understand the
evolution of the biological homochirality. We focus on the electronic chirality measure ($ECM$), a powerful descriptor based on the electronic charge density, for quantifying the chirality degree of a molecule, for a representative set of
chiral molecules, together with their E$_{PV}$ energies. Our results show a novel, strong and positive correlation between $\Delta E_{PV}$ and $ECM$, supporting a subtle interplay between the weak-forces acting within the
nuclei of a given molecule and its chirality. These findings suggest that experimental investigations for molecular parity violation detection should consider molecules with as large $ECM$ values as possible, and may support that a
chiral signature is imprinted on life by fundamental physics via the parity-violating weak interactions.
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Geophysics
Geomagnetic signatures of the slurry F-layer inferred from dynamo simulations
Ludovic Huguet, Thomas Frasson, Souvik Naskar et al. (+5 more)
Seismic observations indicate that the lowermost portion of Earth's
liquid core is density stratified. The existence of this so-called F-layer challenges classical theories of core dynamics, where the geodynamo process that generates Earth's main
magnetic field is assumed to be powered by heat and light element release at the inner core boundary. The seismically-inferred thickness, density, and velocity anomaly can be reproduced by a dynamical model that represents the F-layer as a two-phase two-component slurry on the liquidus, with a “snow” of solid iron particles falling through a quasi-static iron-oxygen
liquid. Here, we present the first fluid dynamical simulations of thermochemically driven rotating convection and dynamo action that include a simple representation of the stratified slurry F-layer at the base of the spherical shell geometry. We show that the F-layer can create a barrier to columnar quasi-geostrophic flow, which is expressed near the core surface as a migration of peak radial and azimuthal flow speeds to lower latitudes as the thickness and stratification strength increase. In dynamo simulations, this effect induces polar minima in the radial
magnetic field at the outer boundary ($B_r$) that strengthen and deepen with increasing stratification, and peaks in latitudinal profiles of $B_r$ moving to lower latitudes with reduced temporal variability. The geomagnetic signature of the F-layer is most prominent in time-averaged $B_r$, when resolved to at least spherical harmonic degree 5, and a trend of increasingly negative zonal degree 3 and 5 Gauss coefficients as the F-layer thickness and stratification strength increase. Our results suggest that an F-layer thickness of 600~km is incompatible with geomagnetic observations and favour weak stratification (normalised Brunt-Väisälä frequency $<1$) and a layer $<400$~km thick.
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All authors Ludovic Huguet, Thomas Frasson, Souvik Naskar, Stephen J. Mason, Andrew T. Clarke, Hannah F. Rogers, Jonathan E. Mound, Christopher J. Davies
Geophysics
Cross-sphere Coupling and Source Inversion of Ionospheric Disturbances Associated with the 2025 Myanmar Strike-slip Earthquake from BeiDou GEO and Multi-GNSS Observations
Jianghe Chen, Pan Xiong, Qingshan Ruan et al. (+6 more)
Focusing on the M7.9 earthquake in Myanmar in 2025, this study comprehensively utilizes data from BeiDou geostationary satellites of the Chinese Continental Crustal Movement Observation Network and multi-system Global
Navigation Satellite Systems (GNSS). The spatiotemporal
evolution characteristics and physical mechanisms of pre-seismic ionospheric anomalies and co-seismic ionospheric disturbances were systematically analyzed. By employing the moving interquartile range method combined with
solar-terrestrial environmental parameters, a negative Total Electron Content (TEC) anomaly associated with the seismogenic region was identified three days before the earthquake. The equatorial conjugate structure of this TEC anomaly revealed a multi-path coupling effect between the lithosphere, atmosphere, and ionosphere. The extraction of Coherent Ionospheric Disturbance (CID) signals based on wavelet transform and band-pass filtering indicated that the co-seismic ionospheric disturbances were dominated by acoustic-
gravity waves in the 2-8 mHz frequency band, propagating at a speed of approximately 1.2 km/s, and exhibiting an asymmetric pattern in the southeast direction. A spatial density-weighted method for locating the source of ionospheric disturbances was proposed, elucidating the joint control mechanism of fault strike-slip motion, geomagnetic field modulation, and equatorial electrojet on the disturbance energy. The results confirm that the high spatiotemporal resolution of BeiDou GEO satellites and multi-system GNSS significantly enhances the capability to capture weak ionospheric anomaly signals associated with earthquakes. These results provide additional observational constraints on space-based Lithosphere-Atmosphere-Ionosphere Coupling (LAIC) processes and may contribute to the development of ionosphere-based earthquake monitoring techniques.
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All authors Jianghe Chen, Pan Xiong, Qingshan Ruan, Xiaoran Zhang, Yuqi Lin, Xuemin Zhang, Ting Zhang, Kaixin Wang, Xuhui Shen
Optics · Cross-listed from hep-ex
Absolute scintillator light yield correction for SiPIN readout via Transfer Matrix Method and Geant4 optical simulation
Ge Ma, Zhiyang Yuan, Chencheng Feng et al. (+3 more)
Precise measurement of the absolute light yield (LY) of scintillators has long been limited by systematic effects inherent in realistic readout geometries. Large-angle incidence, multiple reflections inside the optical housing, and refractive-index mismatch at the coupling interface all introduce biases that cannot be removed by a simple conversion based on the detector's nominal
quantum efficiency. To address this problem, we present a correction method that combines the Transfer
Matrix Method (TMM) with Geant4 optical Monte Carlo simulation. A wave-optics model of the SiPIN surface thin-film stack is used to extract the angle- and wavelength-dependent single-hit detection probability $p_{\mathrm{det}}(\lambda,\theta)$, which is then dynamically coupled into the macroscopic
photon transport simulation, achieving a full-chain integration of the microscopic interface optical response with macroscopic
geometric light collection. We demonstrate the method using a GAGG:Ce
crystal as the test sample. Two types of optical housings – a high-absorption Absorber and a high-reflection Reflector – are each combined with air and optical-grease coupling, forming four independent configurations whose overall
photon-to-signal conversion efficiencies $\alpha_{\mathrm{SiPIN}}$ span more than a factor of three. Despite the very different optical boundaries, the intrinsic light yields derived from the four configurations show excellent mutual consistency (coefficient of variation $= 1.8\%$). The measured intrinsic light yield of GAGG:Ce is $LY_{\mathrm{int}} = (5.63 \pm 0.10_{\mathrm{spread}} \pm 0.16_{\mathrm{syst}}) \times 10^{4}~\mathrm{ph/MeV}$. The correction framework effectively decouples the systematic influence of complex geometry and interface optics from
photon detection, providing a general-purpose scheme for high-precision, traceable scintillator characterization.
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All authors Ge Ma, Zhiyang Yuan, Chencheng Feng, Zirui Yang, Zhenwei Yang, Ming Zeng
Optics
Mid-infrared germanium-on-silicon waveguide sensor for therapeutic drug monitoring of phenytoin
David J. Rowe, Siyu Chen, Mihai-Adrian Panainte et al. (+14 more)
We report the design, fabrication and characterization of evanescent mid-infrared germanium-on-silicon waveguide sensors for therapeutic drug monitoring (TDM). TDM requires rapid and accurate quantification of serum drug levels but existing clinical assays rely on laboratory-based instrumentation that limits point-of-care deployment. In this work, tunable diode
laser absorption spectroscopy was used to analyze dried samples of the anti-seizure medication phenytoin in the spectral region of $\lambda$ = 5.6 - 6.0 $\mu$m. A limit of detection of 2.20 mg/L was achieved for extracted samples, where phenytoin was first added to human serum and subsequently isolated using
liquid-
liquid extraction. This limit is significantly below the therapeutic window of 10 - 20 mg/L for phenytoin, enabling detection of sub-therapeutic concentrations. At the same time, the sensor maintains a consistent dose-dependent response up to 40 mg/L, demonstrating its capability to quantify concentrations across the therapeutic window and above the upper therapeutic limit. This validates the use of silicon photonics for biomedical infrared spectroscopy for patients undergoing drug therapy, whether the serum-drug concentration is either too high or too low. These results highlight the potential of mid-IR integrated photonics to form the basis of compact, scalable platforms for point-of-care TDM.
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All authors David J. Rowe, Siyu Chen, Mihai-Adrian Panainte, Callum J. Stirling, Pin Dong, Monika Bakalarz, Hanuushah Vizabaskaran, Glenn Churchill, Weilin Jin, Georgia Mourkioti, Martin Ebert, Graham T. Reed, Saul N. Faust, James S. Wilkinson, Milos Nedeljkovic, Daniel R. Owens, Goran Z. Mashanovich
Optics
Decoupling of topology and texture in optical skyrmions under turbulence
D. G. Pires and N. M. Litchinitser
Topological structure is widely invoked as a route to disorder-resilient photonic states, yet whether it protects locally resolved field structure under realistic disorder has not been established. Optical skyrmions, vectorial light fields characterized by a global skyrmion number $N_{sk}$, provide a stringent test of this question under
turbulence. Although $N_{sk}$ is expected to be robust, conservation of a global invariant does not guarantee preservation of the underlying polarization texture. Here we reconstruct the full Stokes field of optical skyrmions transmitted through controlled turbulent channels, combining experiment, phase screen simulations, and analytical modelling to independently track global and local observables. We demonstrate a broad disorder regime in which $N_{sk}$ remains conserved while fine polarization structure rapidly degrades. This pronounced decoupling, strengthened for higher-order skyrmions, exposes a hierarchy of robustness between topological invariants and texture-resolved information, defining intrinsic limits of topological protection in disordered wave systems.
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Biological Physics
Rupture-Repair Cycles in Regenerating Hydra Tissues
Oded Agam and Erez Braun
Destructive mechanical breakdowns and fractures are ubiquitous events in driven physical matter; living tissues, by contrast, can rupture repeatedly while restoring integrity. Here we study rupture repair interplay in regenerating Hydra tissues, which cycle through osmotic inflation, pressure release by rupture, and resealing. We utilize bright field imaging of the tissue projected area as a readout of the rupture magnitude before it is arrested. Analyzing these event statistics, we find that the tail of the area-drop distribution is controlled by Ca2+-dependent repair efficiency. When the Ca2+ response is weakened, either by partially blocking gap-junctions mediating the intercellular communication, or by inhibiting stretch-activated Ca2+ channels, the actomyosin force that arrests the rupture process is delayed or reduced. Under these conditions, rare large pressure releases become more likely, and the tail of the distribution crosses over from an exponential behavior, exhibiting a characteristic scale, to a power-law one consistent with a critical-like regime reflecting intermittent rupture propagation. These results identify mechanically evoked Ca2+ activity as a control axis linking repair to rupture statistics in a living tissue. It supports a picture of rupture front advancing by stick-slip-like dynamics as it encounters a heterogeneous mechanical landscape, akin to failure-front propagation in disordered materials.
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Geophysics
Consistent initialization of mixed-dimensional multiphysics models for fractured reservoirs under geomechanical constraints and field measurements
Jakub Wiktor Both and Inga Berre
Modeling coupled processes in fractured porous media – flow, deformation, fracture mechanics, and thermal/chemical effects – often relies on mixed dimensional multiphysics formulations. These systems are nonlinear and depend on physical states and state dependent material laws. While in-situ field measurements consistently describe the deformed
equilibrium configuration, computational models typically start from an idealized reference configuration and require explicit initialization of the in-situ stress state. This mismatch complicates initialization and linearization of constitutive laws. As a consequence, due to the two scale nature of fractured media, this can induce large deviations in fracture aperture directly impacting flow predictions. To address this, a discrete fracture model is introduced whose constitutive laws are expressed with respect to the unknown
equilibrium state. This is paired with a fixed point initialization strategy that consistently reconstructs the reference configuration, consistent with both geomechanical constraints and field measurements up to load-path dependence. This data-consistent strategy provides a foundation for extending models to more complex scenarios, including multiphase and multicomponent flow in fractured reservoirs.
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Instrumentation and Detectors
Simulation Study on the Discrimination of $0\nu\beta\beta$ Events from Single-Electron Events Using Orthogonal-Strip HPGe Detectors
Qiuli Zhang, Wenhan Dai, Peng Zhang et al. (+7 more)
Neutrinoless double beta decay ($0\nu\beta\beta$) offers a sensitive probe of
neutrino mass and its Majorana nature. Orthogonal-strip high-purity germanium (HPGe) detectors with high spatial resolution provide a promising approach for distinguishing $0\nu\beta\beta$ events from single-electron backgrounds. In this work, a simulation framework was developed to evaluate the discrimination performance of these detectors. The framework combined Geant4 simulations with a hybrid numerical-analytical approach to model charge cloud dynamics. A dual-branch convolutional neural network (CNN) was implemented to extract topological features for event classification. The impact of detector geometry on discrimination performance was quantitatively assessed. For a fixed
crystal thickness of 15 mm, the background rejection efficiency decreased from 79.5% to 59.0% as the strip pitch increased from 0.1 mm to 0.5 mm. For a strip pitch of 0.25 mm, a
crystal thickness of 20 mm was found to be optimal, balancing full-energy peak (FEP) efficiency with discrimination capability. These results demonstrate that orthogonal-strip HPGe detectors can effectively suppress single-electron backgrounds, and provide quantitative guidance for detector design in $^{76}$Ge $0\nu\beta\beta$ decay searches.
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All authors Qiuli Zhang, Wenhan Dai, Peng Zhang, Mingxin Yang, Yang Tian, Zhi Zeng, Yulan Li, Ming Zeng, Hao Ma, Jianping Cheng
Fluid Dynamics
Influence of Turbulence Length Scale and Platform Surge Motion on Wake Dynamics in Tandem Floating Wind Turbines
Ahmad Nabhani and Josep M. Bergada
Wake interaction is a key factor limiting the performance of floating offshore wind turbine arrays, yet the combined influence of inflow
turbulence structure and platform motion on wake dynamics remains poorly understood. This study examines how the integral length scale of inflow
turbulence and platform surge motion shapes wake development and power performance in a tandem configuration of two aligned floating offshore wind turbines separated by five rotor diameters. High-fidelity computational fluid dynamics simulations are performed using OpenFOAM, based on Large-Eddy Simulation with an Actuator-Line Model and the Wall-Adapting Local Eddy-Viscosity subgrid-scale closure. Synthetic turbulent inflows are generated using the Divergence-Free Synthetic Eddy Method, with prescribed integral length scales spanning 0.25-1.25 times the rotor radius. Over this range, increasing the integral length scale naturally leads to higher freestream
turbulence intensity, which increases from approximately 1.9% to 7.2%. The corresponding dominant inflow frequencies are extracted from time-resolved velocity signals, yielding Strouhal numbers in the range St approx 0.71 to 0.12. Wake
evolution is analyzed through disk-averaged velocity deficits, turbulent kinetic energy distributions, spectral characteristics,
vortex topology, and time-averaged power coefficients. The results show that the inflow
turbulence integral length scale is the primary parameter controlling wake recovery. Larger integral scales introduce energetic, low-frequency eddies that destabilize the tip-
vortex system, enhance lateral and vertical entrainment, and accelerate wake mixing. These mechanisms lead to substantial reductions in the inter-turbine velocity deficit and translate directly into increased downstream power output...
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Physics and Society
Hilbert entropy for measuring the complexity of high-dimensional systems
Seong-Gyun Im, Taewoo Kang and S. Joon Kwon
Measuring the complexity of high-dimensional data in physical systems becomes a critical factor in determining the information and quality of the systems. However, traditional metrics, such as Lyapunov exponent, fractal dimension, and information
entropy, are limited in measuring contextual higher-dimensional data in that they do not elucidate the intrinsic nature of physical systems. Herein, we introduce a novel methodology for quantifying the complexity of high-dimensional data through dimension reduction yet retaining context using a space-filling curve such as the
Hilbert curve along with generalized
entropy measures. We validate this methodology in measuring critical phenomena, including phase transitions in
spin and percolation models. Our findings demonstrate a high degree of concordance between the
Hilbert entropy and theoretical phase transition points. Moreover, we further proceed to an exploration of the hidden relationship between the
Hilbert entropy and the fractal dimension, such as a linear relationship between scaling exponent and the Euclidean dimension of scale-invariant 2D/3D geometries. The present methodology offers a promising new framework for understanding and analyzing complex systems in higher dimensions, with potential applications across various fields of physics.
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Physics and Society · Cross-listed from econ.EM
Information Geometry of Bounded Rationality: Entropy–Regularised Choice with Hyperbolic and Elliptic Quantum Geometries
Anders Karlström and Christer Persson
Models of bounded rationality include
quantum–like (QL) models, which use
Hilbert–space amplitudes to represent context and order effects, and
entropy–regularised (ER) models, including rational inattention, which smooth expected utility by adding an information cost. We develop a unified information–
geometric framework in which both arise from the same structure on the probability simplex. Starting from the Fisher–Rao geometry of the open simplex $\Delta^{n-1}$, we formulate least–action rationality (LAR) as a variational principle for decision dynamics in amplitude (square–root) coordinates and lift it to the cotangent phase space $N:=T^*\mathbb R^n$ of unnormalised amplitudes. The lift carries its canonical
symplectic form and a para–Kähler geometry. For a linear evaluator $\widehat V=\widehat S+\widehat F$ with symmetric part $\widehat S$ and skew part $\widehat F$, the dynamics separate an evaluative channel from a circulatory (co–utility) channel. On a distinguished zero–residual Lagrangian leaf the flow closes as a split–complex (
hyperbolic) Schrödinger–type
evolution, and observable probabilities follow from a quadratic (Born–type) normalisation. When reduced to the simplex, the induced preference one–form decomposes into an exact utility component and a divergence–free co–utility component whose
curvature measures path dependence. Context effects, order effects, and interference–like deviations from the law of total probability emerge as projections of this latent rational flow. Finally, standard complex (
elliptic)
quantum dynamics arises within this real
symplectic phase space by imposing an additional Kähler polarisation that restricts admissible variations.
Unitary evolution is thus a coherent restriction of the underlying least–action framework rather than a primitive postulate.
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Instrumentation and Detectors
ImpCresst – A versatile simulation tool focusing on solid-state detectors at keV energies
G. Angloher, S. Banik, A. Bento et al. (+57 more)
We present ImpCresst, a Geant4-based Monte Carlo tool to simulate backgrounds from natural and cosmogenic radionuclides, and calibration signals in solid-state detectors and their response to it. It is tuned for a fast-evolving and heterogeneous detector environment with a focus on physics at the keV range. This tool was originally developed and validated by the CRESST collaboration; however, its flexibility and configurability make it suitable for other experiments with similar requirements. Key features of ImpCresst include the dynamic geometry implementation directly from CAD files, ROOT-based data persistency of the whole event
topology and automatic metadata annotation for data provenance, and interfaces to various particle generators, particularly for radiogenic and cosmogenic radionuclides. It includes also a newly developed particle generator for radioactive bulk and surface contaminations which is completely independent of any user defined confinement volumes. The auxiliary tool CresstDS applies detector-specific energy and time resolution based on a user-provided data set of empirical parameterization. We discuss also how to manage an ImpCresst based workflow in an HPC environment based on Apptainer and nextflow.
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All authors G. Angloher, S. Banik, A. Bento, A. Bertolini, R. Breier, C. Bucci, J. Burkhart, L. Burmeister, L. Canonica, F. Casadei, E. Cipelli, S. Di Lorenzo, J. Dohm, F. Dominsky, A. Erb, E. Fascione, F. von Feilitzsch, S. Fichtinger, D. Fuchs, A. Fuss, V.M. Ghete, P. Gorla, P.V. Guillaumon, D. Hauff, M. Ješkovský, J. Jochum, M. Kaznacheeva, H. Kluck, H. Kraus, B. von Krosigk, A. Langenkämper, M. Mancuso, B. Mauri, V. Mokina, C. Moore, P. Murali, M. Olmi, T. Ortmann, C. Pagliarone, L. Pattavina, F. Petricca, W. Potzel, P. Povinec, F. Pröbst, F. Pucci, F. Reindl, J. Rothe, K. Schäffner, J. Schieck, S. Schönert, C. Schwertner, M. Stahlberg, L. Stodolsky, C. Strandhagen, R. Strauss, F. Toschi, I. Usherov, D. Valdenaire, M. Zanirato, V. Zema
Optics
Engineering symmetry-protected topological states in waveguide arrays
Lavi K. Upreti
The topological classification of a system depends on the discrete
symmetries of its
Hamiltonian. In Floquet photonic waveguide arrays, the abstract
symmetries of the Altland–Zirnbauer (AZ) scheme –
chiral, particle-hole, and time-reversal (for photonics, $z$-reversal) – arise from structural properties of the
lattice, yet a systematic correspondence has not been established. Here, we illustrate this correspondence for a simpler system of one-dimensional waveguide arrays with real coupling coefficients, showing how bipartite structure and $z$-reflection
symmetry alone determine the whole AZ class. We further demonstrate that non-bipartite networks – lacking conventional particle-hole
symmetry,
chiral symmetry, and $z$-reversal
symmetry – can nonetheless support topologically protected boundary states at quasienergy $\varepsilon = \pi$, even in one dimension. The protecting
symmetry – shifted-particle-hole
symmetry – applies equally to higher-dimensional Floquet waveguides.
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Applied Physics · Cross-listed from cs.LG
CHLU: The Causal Hamiltonian Learning Unit as a Symplectic Primitive for Deep Learning
Pratik Jawahar and Maurizio Pierini
Current deep learning primitives dealing with temporal dynamics suffer from a fundamental dichotomy: they are either discrete and unstable (LSTMs) \citep{pascanu_difficulty_2013}, leading to exploding or vanishing gradients; or they are continuous and dissipative (Neural ODEs) \citep{dupont_augmented_2019}, which destroy information over time to ensure stability. We propose the Causal
Hamiltonian Learning Unit (pronounced: clue), a novel Physics-grounded computational learning primitive. By enforcing a Relativistic
Hamiltonian structure and utilizing
symplectic integration, a CHLU strictly conserves phase-space volume, as an attempt to solve the
memory-stability trade-off. We show that the CHLU is designed for infinite-horizon stability, as well as controllable noise filtering. We then demonstrate a CHLU's generative ability using the MNIST
dataset as a proof-of-principle.
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Optics
Distinguishing thermal and pseudothermal light by testing the Siegert relation
Xi Jie Yeo, Justin Yu Xiang Peh, Darren Ming Zhi Koh et al. (+2 more)
Thermal light, including blackbody radiation and spontaneous emission, exhibits
photon bunching. Thermal light sources, however, typically yield low spectral densities, limiting their practical utility. Pseudothermal light sources with higher brightness and longer coherence time are often employed instead. While pseudothermal light also exhibits
photon bunching, this property may not suffice to fully replicate the behavior of genuine thermal light. Here we demonstrate a method to directly test the Siegert relation for two sources of
photon-bunched light,
laser light scattered from a rotating ground glass and spontaneously emitted light from a gas discharge lamp, probing a fundamental criterion expected of thermal light.
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All authors Xi Jie Yeo, Justin Yu Xiang Peh, Darren Ming Zhi Koh, Christian Kurtsiefer, Peng Kian Tan
Optics · Cross-listed from quant-ph
High-Performance Quantum Frequency Conversion from Ultraviolet to Telecom Band
Yi Yang, Bin Wang, Ji-Chao Lin et al. (+10 more)
Quantum frequency conversion (QFC) is essential for bridging the spectral gap between stationary
qubits and low-loss optical communication channels. In this work, we demonstrate a short-wavelength-pumping QFC with the first-order quasi-phase matching period of 3.07 um on thin-film lithium niobate, converting ultraviolet
photons to the telecom C-band. By constructing a theoretical model that correlates the normalized conversion efficiency with domain defects in the short-period phase-matched waveguide, we found the critical tolerance of domain defects along the waveguide should be $\le 2$ (excluding the ends). Based on this, we achieved a theoretical limit normalized conversion efficiency of 839%/(W*cm^2) for the fundamental guided mode through fabrication optimization. Furthermore, we propose a robust noise suppression strategy for short-wavelength pumping by utilizing the counter-tuning behaviors of difference-frequency generation and spontaneous parametric down-conversion. By combining these advances with ultra-narrowband filtering, we achieve a record-high external efficiency of 28.8% and an ultra-low noise of 35 counts per second. This high-performance QFC connecting ultraviolet and telecom bands satisfies the stringent requirements for long-lived remote ion-ion
entanglement in scalable
quantum networks [W.-Z. Liu et al., Nature (2026)].
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All authors Yi Yang, Bin Wang, Ji-Chao Lin, Yang Gao, Xin Li, Jiu-Peng Chen, Lei Hou, Ye Wang, Yong Wan, Xiu-Ping Xie, Ming-Yang Zheng, Qiang Zhang, Jian-Wei Pan
Physics and Society
Diversification of global food trade partners increased inequalities in the exposure to shock risks
Ariadna Fosch, Alberto Aleta, Roger Cremades et al. (+1 more)
Recent global food trade disruptions have evidenced how local shocks can cascade into global security threats. While the capacity of food systems to absorb spillovers depends heavily on its underlying trade networks, few studies quantify how their temporal
evolution reshapes systemic vulnerability over time. Here, we evaluate how changes in global connectivity from 1986 to 2022 reshaped responses to production shocks. Using FAO data, we built yearly multiplex representations of the food trade system and quantified robustness through a
stochastic shock-propagation model with dynamic export bans. We find that while increasing globalization intensified inter-dependencies and amplified cascades, robustness trends remain heterogeneous. Grain trade has become more decentralized and resilient to targeted shocks; conversely, Animal and Vegetable Fats exhibit growing centralization and fragility around key exporters like Indonesia and Malaysia. These structural transformations caused diverging shifts in systemic vulnerability, disproportionately threatening already vulnerable regions such as Africa and Southern Asia.
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All authors Ariadna Fosch, Alberto Aleta, Roger Cremades, Yamir Moreno
Fluid Dynamics
Numerical method for strongly variable-density flows at low Mach number: flame-sheet regularisation and a mass-flux immersed boundary method
Matheus P. Severino, Fernando F. Fachini, Elmer M. Gennaro et al. (+2 more)
A low-Mach-number flow, in the laminar regime, has intrinsically two characteristic spatial scales for a given time scale, or two characteristic temporal scales for a given spatial scale, and these dual scales are very different due to the disparity between the flow and acoustic speed. Therefore low-Mach-number flows impose mathematical and computational challenges in their description. Standard numerical methods for compressible flows, which are typically designed for problems with a single dominant spatial and temporal scale, require alternative approaches such as preconditioning techniques or solvers tailored for low-Mach-number equations. The present work introduces a simplified fluid dynamics model for flows at low Mach number, based on the fractional time-step method. The proposed approach is suitable for handling strong temperature gradients and thermal
diffusion, as encountered in combustion systems. To address discontinuities at the flame front in reacting-flow cases, due to the hypothesis of infinitely fast chemistry, a regularisation procedure is employed. Additionally, the immersed boundary method (IBM) is extended to handle mass flux across the boundary surface, enabling simulations of fuel ejection from an arbitrary burner geometry, using a convenient Cartesian grid. The numerical method utilises a predictor-corrector scheme for time integration on a collocated grid, with flux interpolation to prevent numerical pressure oscillations (“odd-even decoupling”). Relevant test cases are used to verify the methods and their implementations, demonstrating correctness and robustness.
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All authors Matheus P. Severino, Fernando F. Fachini, Elmer M. Gennaro, Daniel Rodríguez, Leandro F. Souza
Atmospheric and Oceanic Physics
Analytical insights into the transient climate response
Boriana Chtirkova
The temperature in the transient
climate response is lower than the
equilibrium temperature for the same amount of forcing. The degree of disequilibrium is not constant in time and depends on various
climate parameters. We derive intuition for this by solving the heat equation with a surface temperature feedback for linearly increasing forcing. The surface temperature initially evolves at a slower rate than the corresponding steady state (SS) temperature and it accelerates until quasi-steady state (QSS), when the SS and QSS temperatures evolve in parallel with a constant offset. The offset depends on the rate of forcing and total heat capacity of the system divided by the square of the
climate feedback. The timescale over which the
climate system approaches QSS depends also on the effective ocean mixing and is order of thousands of years. Over societally relevant timescales (around 100 years), the top-of-atmosphere energy imbalance increases, and the actual temperature moves farther from the steady-state temperature expected for the same forcing.
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Chemical Physics · Cross-listed from cond-mat.mtrl-sci
Towards an understanding of magnesium in a biological environment: A density functional theory study
Miranda Naurin, Sally Aldhaim, Moltas Elliver et al. (+3 more)
Density functional theory is used to investigate the interactions between a layer of magnesium hydroxide, Mg(OH)2, the magnesium (Mg) surface Mg(0001), and the three amino acids glycine, proline and glutamine. The aim is to improve the understanding of Mg behavior in biologically relevant environments, such as the ones that biodegradable implants experience in the body. For a simple model of such conditions, adsorption of amino acids are studied. With the layer of Mg(OH)2 as a model of either slightly corroded Mg, or intentionally coated Mg, the interfacial interaction between a layer of Mg(OH)2 and Mg(0001) is first examined in the absence of the molecules. Then follows analyses that include amino acids on top of the Mg(OH)2 layer. We find that the Mg(OH)2/Mg(0001) interaction is weak and that the layer of Mg(OH)2 can readily slide across the Mg surface. The presence of amino acids is found to have a limited influence on the adsorption of Mg(OH)2 on Mg(0001), decreasing the binding by at most 3%, while more layers of Mg(OH)2 strengthen the Mg(OH)2/Mg(0001) binding by 13%. This is still less than the binding of Mg(OH)2 layers within its native bulk structure, and our findings indicate that only a small number of hydroxide layers are required before it is energetically more favorable for Mg(OH)2 to create bulk than to stay on Mg(0001) as single layers. This provides insight into early-stage surface processes relevant for magnesium-based implant materials.
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All authors Miranda Naurin, Sally Aldhaim, Moltas Elliver, Ludwig Hagby, J. Didrik Nilsson, Elsebeth Schröder
Plasma Physics
Atmospheric-Pressure Ar/Air Plasma Jet-Induced Degradation of Azo Dyes in Aqueous Solutions: Kinetic and Mechanistic Insights
Mohammed Shihab, Alaa El-Ashry, Seham A. Ibrahim et al. (+4 more)
Atmospheric-pressure non-thermal
plasmas are promising platforms for advanced oxidation in water treatment, yet quantitative coupling between reactive species delivery, solution chemistry, and molecular fragmentation remains unclear. We investigate degradation of two structurally related azo dyes using an Ar
plasma jet in a
plasma-
liquid discharge configuration with an immersed counter-electrode to enhance interfacial coupling.
Plasma exposure generated a reactive oxygen and nitrogen species environment and strong acidification, increasing
proton concentration up to 49-fold. UV-Vis analysis showed rapid chromophore decay, achieving 0.88 and 0.94 removal within 40 min. Biphasic kinetics indicated a transition from radical-flux-controlled to transport-influenced regimes. Fluorescence and Raman spectroscopy confirmed transient oxidized intermediates and progressive pi-conjugation breakdown, elucidating
plasma-driven oxidative fragmentation mechanisms.
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All authors Mohammed Shihab, Alaa El-Ashry, Seham A. Ibrahim, Sarah Salah, Abdelhamid Elshaer, Nabil El-Siragy, Atef A. Elbendary
Atomic Physics · Cross-listed from quant-ph
Sustaining high-fidelity quantum logic in neutral-atom circuits via mid-circuit operations
Rui Lin, You Li, Le-Tian Zheng et al. (+11 more)
The realization of fault-tolerant
quantum computation hinges on the ability to execute deep
quantum circuits while maintaining gate fidelities consistently above error-correction thresholds. Although neutral-atom arrays have recently demonstrated high-fidelity two-
qubit gates and early-stage logical
quantum processors, sustaining such high performance across deep, repetitive
circuits remains a formidable challenge due to cumulative motional heating and atom loss. Here we demonstrate a sustainable neutral-atom framework that overcomes these limitations by integrating a suite of hardware-efficient mid-
circuit operations. We report a two-
qubit controlled logic gate with a raw fidelity of 99.60(1)%, which is further increased to a fidelity of 99.81(1)% via non-destructive erasure detection. Crucially, by implementing in-
circuit Raman sideband cooling and
qubit re-initialization, we demonstrate that gate fidelities can be maintained at the ~99.8% level across multiple operational rounds without observable degradation. By actively managing the internal and motional
entropy of the system mid-stream, our in-situ refreshable architecture provides a critical pathway for executing the repeated syndrome-extraction cycles required for large-scale, continuous
quantum error correction.
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All authors Rui Lin, You Li, Le-Tian Zheng, Tai-Ran Hu, Si-Yuan Chen, Hong-Ming Wu, Yu-Chen Zhang, Hao-Wen Cheng, Yu-Hao Deng, Zhan Wu, Ming-Cheng Chen, Jun Rui, Chao-Yang Lu, Jian-Wei Pan