Optics
A Route to Pure Optical Rotation in Self-Assembled Materials through Energetic Non-Degeneracy
Daniel J. Gracias, Thomas J. Ugras and Richard D. Robinson
Achieving large optical rotation with minimal ellipticity and absorption, 'pure' optical rotation, remains a central challenge in
chiral photonics. Solution-processed self-assembled materials can exhibit exceptional chiroptical responses (g-factors > 1), yet their circular birefringence (CB) typically overlaps with circular dichroism (CD) and resonant loss (Absorption), leading to elliptical, attenuated signals. Here, we establish a general, theory-guided design principle showing that non-degeneracy provides a route towards pure optical rotation in self-assembled systems. Using a generalized coupled-oscillator framework, we demonstrate that breaking degeneracy between the excited states of interacting chromophores produces CB in spectral regions where CD and absorption are naturally weak. We experimentally validate this mechanism using mixed assemblies of $\alpha$- and $\beta$-CdS magic-sized clusters, which exhibit the predicted off-resonant, emergent CB. Guided by this principle, we design a layered architecture that maximizes non-degenerate neighbors through alternating chromophore planes. This structural architecture results in optical response lineshapes optimized for pure rotation. Because the mechanism relies solely on dipolar coupling and energetic detuning, it is generalizable across wavelengths, including in the ultraviolet (~310 nm), where suitable nanocrystal and organic chromophores are readily available. Simulations predict a 50 meV (12 THz) window exhibiting low-dispersion optical rotation of ~20{\deg}, >40% transmission, and <1{\deg} ellipticity-strong performing
benchmarks typically associated with lithographic metamaterials. These results establish non-degenerate coupling as a general mechanism for engineering chiroptical response and provide a strategy for realizing pure optical rotation in self-assembled systems.
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Instrumentation and Detectors
A precision 32 keV angular-selective photoelectron source for calibration measurements at the KATRIN experiment
Sonja Schneidewind, Rudolf Sack, Fabian Block et al. (+11 more)
The Karlsruhe Tritium
Neutrino (KATRIN) experiment measures the
neutrino mass from a precise measurement of the endpoint region of the kinematic tritium beta-decay spectrum by using a spectrometer combining
magnetic adiabatic collimation and electrostatic filtering (MAC-E filter). For calibration purposes, KATRIN uses a monoenergetic angular-selective photoelectron source. We present an upgrade of this source, which was installed in the KATRIN beamline in February 2022. The source allows for a wide range of accessible electron energies up to 32 keV and a variation of the angle with regard to the
magnetic field. These features are used for precise measurements of electron scattering effects off tritium molecules in KATRIN's gaseous tritium source, for investigations of angular-dependent backscattering for example at KATRIN's focal-plane detector, and for studies on adiabatic transport in the main spectrometer.
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All authors Sonja Schneidewind, Rudolf Sack, Fabian Block, Sanshiro Enomoto, Volker Hannen, Christoph Köhler, Alexey Lokhov, Alexander Marsteller, Hans-Werner Ortjohann, Richard Salomon, Lutz Schimpf, Klaus Schlösser, Sascha Wüstling, Christian Weinheimer
Medical Physics
The FLASH enigma
Diana Shvydka, Victor Karpov and Nilendu Gupta
We consider physics behind the FLASH modality of cancer radiation treatment where extremely short treatment times are achieved with ultra high dose rates maintaining the conventional antitumor effectiveness and yet substantially reducing damage to normal tissues (sparing effect). The difference in responses between normal and tumor tissues is attributed here to different recombination rates related to their structure morphologies: ordered in normal vs disordered in the tumor tissues. Correspondingly different are their charge densities under ionizing radiation. In normal tissues it is high enough to form electron-hole
liquid (EHL). Because of low EHL diffusivities, the chemical reaction and generation of free radicals are suppressed; hence, sparing effect. To the contrary, a disordered tumor tissue renders efficient energy relaxation channels forming antitumor free radicals. We describe the FLASH thresholds for doses and dose rates.
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Fluid Dynamics
Droplet Impact on Microparticle Raft: Wettability, density and size govern splashing and microplastic ejection from rafts under raindrop impact
Muhammad Hamza Iqbal, Alfonso Arturo Castrejón-Pita, José Rafael Castrejón-Pita et al. (+1 more)
Raindrop impact on the ocean has been proposed as a mechanism for microplastic transfer from seawater to the atmosphere, yet the interfacial dynamics governing particle ejection from floating microplastics remain largely unexplored. We investigate droplet impact onto microparticle monolayers (rafts) spanning a wide range of sizes, contrasting densities, and wettabilities, under raindrop-relevant impact conditions. Particle rafts strongly influence splash dynamics, cavity collapse, and Worthington jet formation. Splash onset is controlled by particle-induced roughness and capillary adhesion: deeply immersed particles stabilise the spreading lamella, producing only microdroplets, whereas weakly immersed particles destabilise the rim, promoting fingering and splashing. Following impact, raft characteristics govern wave-swell dynamics, separating into elastic and rigid regimes. Superhydrophobic rafts enable particle ejection upon impact and form particle-armoured Worthington jets that fragment into
liquid marbles, providing an efficient aerosolisation pathway. In contrast, less hydrophobic rafts show limited detachment upon impact but still support Worthington jet-mediated transport. Despite these differences, splash thresholds and Worthington jet heights collapse under a simple
geometric-inertial-capillary scaling. These results show how particulate monolayers modify canonical droplet-impact and identify the interfacial conditions under which rainfall transfers microplastics from ocean to atmosphere, and inform related droplet-granular processes such as soil erosion, and impacts on sandy substrates.
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All authors Muhammad Hamza Iqbal, Alfonso Arturo Castrejón-Pita, José Rafael Castrejón-Pita, Miguel A. Quetzeri Santiago
Applied Physics · Cross-listed from cond-mat.mes-hall
Flexural Cavity Mechanics in Electrostatically Driven 1D Phononic Crystal
Vishnu Kumar, Bhargavi B.A. and Saurabh A. Chandorkar
Phononic
Crystals provide a versatile platform for controlling
phonons in applications such as waveguiding, filtering, and sensing. To minimize dissipation, cavity resonators are often embedded within the bandgap of phononic
crystals and integrated with suitable transduction techniques. Here, we demonstrate one-dimensional (1D) phononic transmission using electrostatic transduction, enabling the realization of high-quality mechanical oscillators. Using a double-ended tuning fork resonator embedded in a 1D phononic
crystal, we observe degenerate flexural modes (in-phase and out-phase) exhibiting enhanced and comparable quality factors within the same device due to mode degeneracy. The in-phase mode, whose frequency lies inside the phononic bandgap, shows an approximately two-fold increase in quality factor compared to an anchored resonator, while this enhancement diminishes for the out-phase mode (frequency outside the bandgap) at temperatures where thermoelastic dissipation is negligible. This approach offers a promising route toward low-loss, encapsulated phononic devices for sensing and signal processing applications.
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Fluid Dynamics
Mixing with viscoelastic waves at low Reynolds numbers
Enrico Turato, Christelle N. Prinz, Jason P. Beech et al. (+1 more)
Mixing at the microfluidic scale is challenging due to the low Reynolds numbers and often high Péclet numbers. Without
turbulence, mixing relies solely on
diffusion, resulting in slow and inefficient mixing. We demonstrate enhanced mixing in a simple Y-shaped microfluidic channel using viscoelastic
turbulence in fluids containing macromolecules, suchas DNA and polyethyleneoxide. We investigated mixing at two distinct scales: the mixing of small molecules and the mixing of
polymers. We show how the viscoelastic fluctuations fold the solvent, resulting in enhanced reaction rate between two reagents. We also show how the viscoelastic
turbulence enhances the mixing of the macromolecules. We discuss optimization strategies taking into account mixing efficiency, mixing time, mixing length and energy efficiency. Viscoelastic
turbulence unlocks rapid mixing in microfluidic channels where conventional
turbulence cannot operate, offering a versatile platform for applications ranging from chemical synthesis to biomedical assays.
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All authors Enrico Turato, Christelle N. Prinz, Jason P. Beech, Jonas.O Tegenfeldt
Chemical Physics
Velocity Gauge for Oscillator Strength in $\Delta$SCF theory
Yang Shen, Yichen Fan and Weitao Yang
Delta self-consistent-field ($\Delta$SCF) theory is widely used for electronic excitation energy calculations. However, calculating the corresponding oscillator strengths is challenging. The corresponding many-electron wavefunctions are not directly accessible. Both the ground-state and the excited-state wave functions from $\Delta$SCF are described by reference Kohn-Sham (KS) single-determinant wavefunctions for the fictitious non-interacting systems. The non-orthogonality between the ground and excited Kohn-Sham determinants from two different SCF calculations leads to unphysically origin-dependent transition properties, such as transition dipole moment and length-gauge oscillator strength. Including
nuclei contribution in the perturbation is theoretically rigorous, but its effectiveness is only limited to neutral systems, as we show theoretically and numerically. While several other practical approaches have been proposed to tackle the non-orthogonality problem and yield reasonable results, inevitably the determinant of the ground state or the excited state is changed, as well as the density
matrix. In this work, we explore the use of the velocity gauge to compute oscillator strength within $\Delta$SCF theory. We demonstrate that the velocity gauge is capable of naturally accounting for the non-orthogonality of $\Delta$SCF KS wavefunctions and offering origin-independent predictions without any additional correction schemes to the KS wavefunctions. Compared to the length-gauge results obtained via symmetric orthogonalization, velocity gauge can offer comparable results. Furthermore, the adoption of
spin-purified singlet excitation energy in the velocity-gauge transition dipole moment significantly enhances the overall performance of the velocity gauge for $\Delta$SCF oscillator strength predictions on conjugated chromophores.
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Instrumentation and Detectors
Upgrade of the Trigger and Data Acquisition System for Continuous Imaging and Multi-Camera Operation in CYGNO
F. D. Amaro, R. Antonietti, E. Baracchini et al. (+41 more)
The CYGNO experiment employs an optical readout to image particle interactions in a gaseous Time Projection Chamber (TPC), combining cameras and photomultiplier tubes (PMTs) to achieve high spatial resolution and timing information. This approach enables detailed track reconstruction but poses significant challenges for data acquisition, particularly in view of the next experimental phase, CYGNO-04, which will operate multiple cameras simultaneously. In this paper, we present an upgrade of the CYGNO Trigger and Data Acquisition (T-DAQ) system, developed starting from the LIME configuration and validated on the MANGO prototype. The upgrade introduces a continuous imaging acquisition mode, substantially reducing the camera dead time, together with an extended trigger time-tagging scheme that provides a robust global time reference for PMT signals. A synchronous multi-camera DAQ architecture is also implemented and tested, enabling coordinated operation of multiple optical sensors without a master camera. The performance of the upgraded system is validated through dedicated tests, demonstrating stable continuous acquisition, reliable time-tagging, and consistent synchronization across multiple cameras. These results establish a solid and scalable foundation for the CYGNO-04 DAQ and represent a key step toward efficient data acquisition in future large-scale optical TPC detectors.
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All authors F. D. Amaro, R. Antonietti, E. Baracchini, L. Benussi, C. Capoccia, M. Caponero, L. G. M. de Carvalho, G. Cavoto, I. A. Costa, A. Croce, M. D'Astolfo, G. D'Imperio, G. Dho, E. Di Marco, J. M. F. dos Santos, D. Fiorina, F. Iacoangeli, Z. Islam, E. Kemp, H. P. Lima Jr, G. Maccarrone, R. D. P. Mano, D. J. G. Marques, G. Mazzitelli, P. Meloni, A. Messina, V. Monno, C. M. B. Monteiro, R. A. Nobrega, G. M. Oppedisano, I. F. Pains, E. Paoletti, F. Petrucci, S. Piacentini, D. Pierluigi, D. Pinci, F. Renga, A. Russo, G. Saviano, P. A. O. C. Silva, N. J. Spooner, R. Tesauro, S. Tomassini, D. Tozzi
Applied Physics
A semi-analytical geometrical acoustics method for numerical simulation of ultrasound based motion sensing
Vamshi Krishna Chillara and Wontak Kim
We present a semi-analytical geometrical acoustics method to numerically simulate ultrasonic signal characteristics pertinent to motion sensing applications in indoor environments. The proposed methodology treats motion sensing from the first-principles in the sense that the expressions for acoustic field from the source, that scattered by the target and then received at the receiver are all derived from a kinematic standpoint incorporating target motion into consideration. A series of examples are presented throughout to demonstrate the effect of source directivity, wall reflections, and motion trajectories on the Doppler signal strength and frequency characteristics observed for motion sensing applications. Finally, we present a comparison of simulated results with experimental results on data acquired with a human target moving in an environment with an ultrasonic source and receiver. We specifically compare the baseband signal characteristics and their corresponding Short-time
Fourier Transforms that depict Doppler frequency characteristics and show them to be in good qualitative agreement.
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Instrumentation and Detectors
Towards high-pressure noble gaseous detectors for coherent elastic neutrino-nucleus scattering
Leire Larizgoitia
Coherent elastic
neutrino-
nucleus scattering (CE$\nu$NS) is a dominant low-energy
neutrino interaction that remains experimentally challenging due to its weak-scale cross section and the small
nuclear recoil energies involved. This thesis explores the scientific motivations and technical feasibility of CE$\nu$NS\ detection, emphasizing the use of diverse
neutrino sources -reactor, spallation, and
solar- and multiple target materials. The European Spallation Source (ESS) is identified as a particularly promising site, with simulations indicating an optimal signal-to-background ratio achievable with minimal shielding at a location $\sim$24 meters from the tungsten target. Alternative facilities, such as JPARC-MFL, are also evaluated given construction delays at ESS. A significant contribution of this work is the development of a compact, low-cost, 4$\pi$
neutron scatter camera with integrated optical imaging, capable of characterizing
neutron backgrounds and localizing sources using advanced discrimination
algorithms and neural networks. Additionally, the thesis presents the design and early testing of GanESS, a novel high-pressure noble gas time projection chamber with electroluminescence amplification, optimized for CE$\nu$NS detection using argon, xenon, or krypton. The Gaseous Prototype (GaP) demonstrates a promising energy threshold of 0.42$\pm$0.04 $\rm{keV}_{\rm{ee}}$ at 8.62 bar of argon and stable high-pressure performance. Detailed simulations using Garfield++ and COMSOL provide insights into electroluminescence behavior and threshold estimation, although some non-linear detector responses at low E/p remain unresolved. Overall, this work establishes a robust foundation for CE$\nu$NS studies at spallation sources and advances detection technologies with broader implications for
neutrino physics and rare-event searches.
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Optics
Extreme light confinement mediated by the transverse Kerker effect
Sergei Gladyshev, Connor Heimig, Adrià Canós Valero et al. (+7 more)
Dielectric nanoparticles can be engineered to scatter light predominantly in the transverse direction, a phenomenon known as the transverse Kerker effect. Although complete cancelation of forward scattering from a single object is forbidden by the optical
theorem, we show that a single photonic mode can nonetheless realize an ideal transverse Kerker effect. The mode remains dark under normal incidence but evolves into an accidental bound state in the continuum when the nanoparticles are arranged in metasurfaces. This enables a new route to polarization-independent quasi-bound states in the continuum whose quality factors are tunable without
symmetry breaking. We experimentally demonstrate our concept in the visible, achieving the first polarization-independent bound state in the continuum without the need for Brillouin-zone folding. Furthermore, we show that our modes maintain large quality factors over a substantially broader region of momentum space than conventional bound states in the continuum. Our results establish a platform for realizing ultranarrow resonances free of the constraints for designs with standard bound states in the continuum.
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All authors Sergei Gladyshev, Connor Heimig, Adrià Canós Valero, Dmytro Gryb, Tao Jiang, Angana Bhattacharya, Sebastian A. Schulz, Peter Banzer, Andreas Tittl, Thomas Weiss
Chemical Physics
Transfer Learning Meets Embedded Correlated Wavefunction Theory for Chemically Accurate Molecular Simulations: Application to Calcium Carbonate Ion-Pairing
Xuezhi Bian and Emily A. Carter
Achieving chemical accuracy for molecular simulations remains a central challenge in computational chemistry. Here, we present an embedded correlated wavefunction transfer learning (ECW-TL) framework for accurately simulating molecular dynamics in the condensed phase. ECW-TL incorporates high-level electron exchange and correlation effects in ECW theory while preserving training and computational efficiency of machine learned interatomic potentials. We demonstrate the framework on Ca2+-CO32- ion pairing in aqueous solution, a key process underlying CO2 mineralization in seawater. As proof of principle, we first show that finetuning a DFT-revPBE-D3(BJ) baseline model with embedded-DFT-SCAN data reproduces the DFT-SCAN free-energy surface within 1 kcal/mol across all solvation states. Extending the framework to embedded MP2 and localized natural-orbital CCSD(T) further refines the free-energy profile, revealing the crucial role of exact electron exchange and correlation in determining ion-pair stability and structure. ECW-TL thus provides a general, data-efficient route for transferring CW accuracy to large-scale simulations of complex aqueous and interfacial chemical processes.
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Optics
Programmable pixel-mode linear interferometers using multi-plane light conversion
Mushkan Sureka, Itay Ozer, Wenhua He et al. (+3 more)
Programmable linear optical interferometers are a core primitive in optical signal processing,
quantum information processing, and photonic computing. Existing photonic-integrated implementations realize arbitrary $M$-mode
unitaries using Mach–Zehnder-interferometer meshes whose footprint and accumulated loss scale with $O(M^2)$ optical components. Here we analyze and experimentally demonstrate a programmable architecture for implementing linear optical transformations directly on spatially tiled free-space pixel modes using multi-plane light conversion (MPLC). In this architecture, $M$ spatial modes arranged on a transverse
lattice undergo a
unitary transformation and are mapped to $M$ output modes of identical geometry through a sequence of programmable phase masks separated by free-space propagation segments. Numerical simulations show that arbitrary $M$-mode
unitaries can be compiled to a desired high fidelity using a number of phase planes that scales approximately linearly with $M$. Using a spatial-light-modulator-based MPLC, we experimentally demonstrate programmable interferometers acting on up to $16$ spatial pixel modes, including tunable beamsplitters, Hadamard
unitaries, spatial permutations, and partial
unitaries on select subsets of modes. These results establish MPLC-based pixel-mode interferometers as a promising architecture for programmable linear optics with applications in classical and
quantum optical interconnects, photonic switching, and
quantum information processing.
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All authors Mushkan Sureka, Itay Ozer, Wenhua He, Michael R. Grace, Chaohan Cui, Saikat Guha
Geophysics
High-Resolution Trans-Oceanic Distributed Acoustic Sensing Enabled by a Bi-Directional Sensor Implementation
Mikael Mazur, Nicolas K. Fontaine, Roland Ryf et al. (+14 more)
We demonstrate continuous distributed acoustic sensing over a 4400km long undersea cable. Bi-directional operation improves the strain signal-to-noise rate by >20dB, enabling 88000 50-m-spaced measurement points at a nominal telecom launch power.
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All authors Mikael Mazur, Nicolas K. Fontaine, Roland Ryf, Martin Karrenbach, Kristopher McBrian, Keith McLaughlin, Brian Sperry, Anuar Butler, Valey Kamalov, Lauren Dallachiesa, Ells Burrows, David Winter, Haoshuo Chen, Jeewan Naik, Kishore Padmaraju, Ajay Mistry, David Neilson
Fluid Dynamics · Cross-listed from math.NA
Efficient and Accurate Surrogate Modeling of Turbulent Flows via Space-Dependent Aggregation and Reduced Order Models
Piero Zappi, Anna Ivagnes, Niccolò Tonicello et al. (+1 more)
Reynolds-Averaged Navier-Stokes (RANS) models are widely used for turbulent flow simulations due to their computational efficiency, but their accuracy strongly depends on the selected
turbulence closure and may vary across the flow domain. Space-dependent model aggregation has been shown to improve RANS predictions by combining multiple
turbulence models, although at the cost of repeated high-fidelity simulations. The first novelty of this work is a unified framework that combines different
turbulence models, space-dependent aggregation, and non-intrusive reduced order models to achieve both accuracy and efficiency. Two aggregation pipelines are proposed: a Mixed FOM-ROM (MFR) approach, where a reduced order model is trained on aggregated RANS solutions, and a Mixed-ROM (MR) approach, which directly aggregates multiple reduced order models built on top of different RANS full-order models. The second novelty is that the aggregation weights are learned via a neural-network that provides smooth, space-continuous weights and improves generalization with respect to standard weighting techniques. The resulting surrogate models are validated on the two-dimensional periodic hill
benchmark and on the flow over a height-dependent bump, demonstrating improved accuracy over individual RANS and ROM predictions at near real-time computational cost.
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All authors Piero Zappi, Anna Ivagnes, Niccolò Tonicello, Gianluigi Rozza
Atomic Physics · Cross-listed from hep-ph
Probing keV mass QCD axions with the SACLA X-ray free electron laser
Charles Heaton, Jack W. D. Halliday, Taito Osaka et al. (+12 more)
Axions are hypothetical particles, proposed to account for the invariance of CP
symmetry in
quantum chromodynamics. While
axions and
axion-like-particles are well-motivated by string theory and beyond-Standard-Model extensions, they have remained elusive to experimental searches even after significant effort over many decades. Building on a recent development using an X-ray free electron
laser to search for cosmologically favoured
axions of mass $m_{a} \lesssim 0.01$ eV, we extend previous bounds on the ALP-
photon coupling, $g_{a\gamma\gamma}$, by over an order of magnitude. We exploit the Bormann effect of Laue
crystals in a light-shining-through-wall experiment, with broad sensitivity to $m_a \lesssim$ 22 eV. Moreover for $m_{a} \in$ (3460, 3480) eV our sensitivity reaches down to the QCD
axion coupling prediction, providing the most stringent laboratory constraints in this mass range.
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All authors Charles Heaton, Jack W. D. Halliday, Taito Osaka, Ichiro Inoue, Sifei Zhang, Ahmed Alsulami, Joshua T. Y. Chu, Mila Fitzgerald, Takaki Hatsui, Motoaki Nakatsutsumi, Haruki Nishino, Atsushi O. Tokiyasu, Robert Bingham, Subir Sarkar, Gianluca Gregori
Chemical Physics
On the performance of QTP functionals applied to second-order response properties II: Dynamic polarizability and long-range C$_6$ coefficients
Rodrigo A. Mendes, Peter R. Franke, Ajith Perera et al. (+1 more)
This work is the second in the series "On the performance of QTP functionals applied to second-order response properties." In the first paper (J. Chem. Phys. 162, 054105, 2025), we demonstrated the good performance of
Quantum Theory Project functionals in predicting static perturbed second-order properties, such as static polarizabilities,
nuclear magnetic resonance (NMR)
spin-
spin coupling constants, and NMR chemical shifts. In the present study, we focus on frequency-dependent properties, namely dynamic polarizabilities and C$_6$ dispersion coefficients. For completeness, a total of 25 exchange-correlation (XC) functionals were investigated. Dynamic polarizabilities were evaluated at five different perturbation wavelengths: 632.99 nm, 594.10 nm, 543.52 nm, 514.50 nm, and 325.13 nm. This property was also computed using HF and EOM-CCSD. In general, EOM-CCSD results are very close to those obtained with linear-response CC3, except at the highest frequency. Among Kohn-Sham calculations, TPSS0 and QTP01 showed the best overall performance for dynamic polarizabilities. We also assessed how well QTP functionals reproduce the pole structure of the CO molecule. For the C$_6$ dispersion coefficients, calculations were performed using the Casimir-Polder equation. The best overall performance was obtained with O3LYP; however, the first eleven ranked functionals show very similar accuracy. Within the QTP family, QTP01 and LC-QTP provide the best results for C$_6$ coefficients.
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All authors Rodrigo A. Mendes, Peter R. Franke, Ajith Perera, Rodney J. Bartlett
Atomic Physics
Physics-informed neural networks for solving saddle-point equations in strong-field physics with tailored fields
Jiakang Chen, Sufia Hashim and Carla Figueira de Morisson Faria
We develop an unsupervised physics-informed neural network to solve saddle-point equations (SPEs) governing direct above-threshold ionization (ATI) within the strong-field approximation. This setting provides a well-understood testbed in which the saddle-point structure is known for tailored driving fields, enabling systematic validation of the proposed solver. The network is trained by minimizing the residual of the SPEs and requires only the definition of the driving-field shape and its parameters, such as intensity, carrier-envelope phase, ellipticity, and relative phase. We introduce a window parametrization strategy that maps network outputs to prescribed regions of the complex-time plane, guiding the optimization toward physically relevant solutions and improving convergence stability. We
benchmark the PINN against a conventional solver for a range of fields, demonstrating robust recovery of the dominant complex ionization times over wide parameter ranges. The network tracks changes in ionization event dominance as
laser parameters are varied, enabling exploration of regimes where conventional solvers require repeated manual initialization. Using the PINN-derived solutions, we compute coherent ATI photoelectron momentum distributions and show the
symmetries of the driving fields are reflected in both the saddle-point structure and the resulting spectra. These results establish PINNs as a promising framework for semiclassical strong-field calculations and provide a foundation for extending machine-learning solvers to Coulomb-corrected models or to more complex processes, such as rescattered ATI for which the SPEs are highly nonlinear and the presence of multiple closely-spaced solutions makes conventional Newton-type root-finding highly sensitive to initial guesses, which hinders systematic investigations across
laser-parameter spaces, particularly for tailored fields.
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Space Physics
Ground Effects of the 2024 Mother's Day Superstorm: A Multi-source Observational Analysis
Yue Chen, Kyoung Ho Kim, Steven K. Morley et al. (+1 more)
This report presents a brief review of the 2024 Mother's Day superstorm and its impacts on the near-Earth space environment and the ground-level effects, with emphasis on the latter. Drawing upon observations from multiple sources. we qualitatively illustrate how intense space weather disturbances can generate strong geoelectric fields and drive pronounced geomagnetically induced currents, as reported at numerous locations, particularly within the New Zealand power grids.
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All authors Yue Chen, Kyoung Ho Kim, Steven K. Morley, Jesse R. Woodroffe
Biological Physics
Biomedical active matter: Emergence and breakdown of collective functionalities
Arnold Mathijssen, Hamed Almohammadi, Lauren Altman et al. (+13 more)
Living systems are made of active materials with microscopic components that work together to perform macroscopic biological tasks. The breakdown of these collective functionalities leads to diseases, which, conversely, could be treated by exploiting self-organization in healthcare technologies. Here, we review recent advances in this rapidly growing field of biomedical active matter. The main themes are (1) collective self-assembly and spatiotemporal coordination; (2) collective motion, transport, and
navigation; (3) collective sensing, signaling, and communication; and (4) collective adaptation,
evolution, and learning. We discuss these emerging processes in a wide range of systems, including
protein folding, biomolecular condensates, cytoskeleton dynamics, intracellular flows, bacterial biofilms, quorum sensing, cilia synchronization, wound healing, biolocomotion,
neurons, endocrine signalling, and cardiovascular flow networks. For each, we highlight medical conditions associated with reduced collective functionality and how they may be treated using microrobotic swarms, bioinspired metamaterials, diagnostics, lab-on-chip devices, organoids, and other active and adaptive matter innovations.
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All authors Arnold Mathijssen, Hamed Almohammadi, Lauren Altman, Talia Calazans, M. J. Ferencz, Michelle Fung, Ian J. Lee, Maciej Lisicki, Ivy Liu, Maggie Liu, Tianyi Liu, Ernest Park, Ran Tao, Albane Thery, Zeyuan Wang, Margot Young
Data Analysis and Statistics · Cross-listed from astro-ph.IM
py5vec: a modular Python package for the 5-vector method to search for continuous gravitational waves
Luca D'Onofrio, Federico Muciaccia, Lorenzo Mirasola et al. (+7 more)
We present py5vec, a Python package for implementing and extending the 5-vector method, used to search for continuous gravitational wave (CW) signals. We also provide a comprehensive theoretical review of the 5-vector method and extend the relative likelihood formalism by marginalizing over the noise variance, resulting in a more robust Student's t-likelihood, and over the initial phase to account for
pulsar glitches. py5vec provides a modular architecture that separates data representation, signal demodulation, and statistical inference into independent abstract stages. It supports multiple input data formats and interoperates with existing Python software, providing a bridge between different approaches. For example, using a bilby-based interface, py5vec implements
Bayesian parameter estimation within the 5-vector formalism for the first time. The modular design also allows for making exact multi-level and direct comparisons between other software, such as cwinpy and SNAG in MATLAB. In py5vec, we implement a multidetector targeted search for known
pulsars, validated using LIGO data from the O4a run and hardware injections, demonstrating consistent reconstruction of signal parameters. This package therefore provides a flexible platform for current targeted searches and for future extensions to other CW search strategies.
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All authors Luca D'Onofrio, Federico Muciaccia, Lorenzo Mirasola, Matthew Pitkin, Cristiano Palomba, Paola Leaci, Francesco Safai Tehrani, Francesco Amicucci, Lorenzo Silvestri, Lorenzo Pierini
Plasma Physics
The properties of plasma sheath containing the primary electrons with a Cairns-distribution
Yida Zhang and Jiulin Du
We study the properties of
plasma sheath containing the cold positive ions, the secondary electrons, and the primary electrons with a Cairns-distribution (a non-thermal velocity-distribution). We derive the generalized Bohm criterion and Bohm speed, the new floating potential at the wall, and the new critical secondary electron emission coefficient. We show that these properties of the
plasma sheath depend significantly on the a-parameter in the non-thermal a-distribution, and so they are generally different from those of the
plasma sheath if the primary electrons were assumed to be a Maxwellian distribution.
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Optics · Cross-listed from gr-qc
Optical Magnus effect on gravitational lensing
Yusuke Nishida
The optical Magnus effect refers to transverse shift of a trajectory of light caused by its polarization and appears as a correction to geometrical optics at the linear order in wavelength. Here, we start from Maxwell's equations in a curved spacetime to derive the equation of motion for a wave packet of circularly polarized light, which confirms the known result involving the helicity-dependent anomalous velocity with some generalization and clarification. We then study possible consequences of the optical Magnus effect on gravitational
lensing in the Schwarzschild spacetime as well as under a weak gravitational potential in an expanding spacetime. Among others, by formulating the lens equation modified to incorporate the optical Magnus effect, the Einstein ring is found impossible to emerge from a point source for any axially symmetric thin lens. Analytic solutions to the modified lens equation are also obtained for simple lens models, illuminating how image formation is affected by the optical Magnus effect.
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Fluid Dynamics
Non-inertial hydrodynamics of manipulating particle transport
Partha Kumar Das
Inspired by numerous lab on a chip, biomedical and bioengineering applications such as
cell sorting, focusing, trapping, and filtering of particles, manipulation of micron sized particle trajectories has been of significant interest in the context of microfluidics. Systematic deflection of microparticles away from their initial streamlines is a central objective in microfluidic particle manipulation. In many widely used microfluidic platforms including deterministic lateral displacement (DLD) devices, density matched, force free particles suspended in low Reynolds number flows encounter arrays of obstacles that potentially breaks the flow
symmetry and alter their trajectories. Despite the prevalence of these devices, the physical mechanism responsible for particle deflection from encountering obstacle wall in strictly non inertial flows (Stokes flows) remains incompletely understood and is often attributed to short range contact interactions rather than hydrodynamic effects.
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Optics · Cross-listed from cond-mat.stat-mech
Non-Thermal Aging of Supercooled Liquids in Optical Cavities
Muhammad R. Hasyim, Arianna Damiani and Norah M. Hoffmann
Aging is a hallmark of disordered materials such as glasses, plastics, and pharmaceuticals, where it often limits long-term stability and performance. In practice, aging is controlled through global parameters like temperature or pressure, which act uniformly on the entire system. Here we introduce a fundamentally different approach, using light confined in optical cavities as a precise and selective tool to guide aging dynamics. We show that a supercooled
liquid coupled to an optical cavity undergoes non-thermal aging, where aging is induced by light without a thermal quench. Light selectively pumps fast vibrational modes while the bath temperature remains unchanged, reshaping the slow structural dynamics of the
liquid. The cavity-coupled
liquid thereby behaves as if it were structurally colder than its surroundings. Exploiting this effective structural cooling together with the timescale separation, we introduce cavity configurational feedback ($\mathrm{C^2F}$) cooling, which uses cavity coupling to reach progressively lower structural temperatures. Our results establish a connection between glass physics and strong light-matter interactions and open a new route toward optical control of aging, glass formation, and nonequilibrium materials dynamics.
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Physics and Society · Cross-listed from stat.AP
Differential Privacy for Network Connectedness Indices
Tom A. Rutter, Yuxin Liu and M. Amin Rahimian
Researchers increasingly use data on social and economic networks to study a range of social science questions, but releasing statistics derived from networks can raise significant
privacy concerns. We show how to release network connectedness indices that quantify assortative mixing across node attributes under edge-adjacent differential
privacy. Standard
privacy techniques perform poorly in this setting both because connectedness indices have high global sensitivity and because a single node's attribute can potentially be an input to connectedness in thousands of
cells, leading to poor composition. Our method, which is straightforward to apply, first adds noise to node attributes, then analytically debiases downstream statistics, and finally applies a second layer of noise to protect the presence or absence of individual edges. We prove consistency and asymptotic normality of our
estimators for both discrete and continuous labels and show our method works well in simulations and on real networks with as few as 200 nodes collected by social scientists.
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Fluid Dynamics
Unified scaling and shape laws for turbulent premixed methane and hydrogen jet flames
Aurora Maffei, Thomas L. Howarth, Marianna Cafiero et al. (+4 more)
The scaling of turbulent premixed flames is typically described by correlations derived for unity-Lewis-number fuels. However, their validity for hydrogen (H$_{2}$) remains uncertain due to the thermodiffusive effects associated with its low Lewis number. In this study, turbulent premixed H$_{2}$ and methane (CH$_{4}$) jet flames are systematically compared over a wide range of operating conditions. Experiments were conducted for Reynolds numbers between 5000 and 60000 and effective Karlovitz numbers spanning 3-368. Flame structure and global flame geometry were characterized using spatially resolved OH$^{*}$ chemiluminescence imaging, allowing consistent comparison between the two fuels across different
turbulence intensities. The results are interpreted via a unified framework that incorporates two thermodynamic- and fuel-dependent parameters: a flame speed factor, $\alpha$, representing the enhancement of local burning rates, and a shape factor, $\gamma$, describing the scaling of mean flame geometry. Despite significant fuel-specific thermodiffusive effects associated with preferential
diffusion and intrinsic reactivity, which lead H$_{2}$ flames to exhibit enhanced sensitivity to
turbulence and more compact flame configurations, both H$_{2}$ and CH$_{4}$ flames are found to exhibit robust and consistent turbulent scaling behavior when analysed within the proposed unified framework. The resulting correlations provide a generalised description of turbulent burning velocity and flame structure, demonstrating that key
turbulence-chemistry interactions can be captured within a common model across fuels with widely different Lewis numbers. Overall, the
dataset spans multiple
turbulence regimes and flame geometries for both fuels, providing a valuable experimental
benchmark for the validation of turbulent combustion models across different regimes.
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All authors Aurora Maffei, Thomas L. Howarth, Marianna Cafiero, Florence Cameron, Michael Gauding, Joachim Beeckmann, Heinz Pitsch
Applied Physics · Cross-listed from cs.LG
Physics-Informed Neural Systems for the Simulation of EUV Electromagnetic Wave Diffraction from a Lithography Mask
Vasiliy A. Es'kin and Egor V. Ivanov
Physics-informed neural networks (PINNs) and neural operators (NOs) for solving the problem of diffraction of Extreme Ultraviolet (EUV) electromagnetic waves from contemporary lithography masks are presented. A novel hybrid Waveguide Neural Operator (WGNO) is introduced, based on a waveguide method with its most computationally expensive components replaced by a neural network. To evaluate performance, the accuracy and inference time of PINNs and NOs are compared against modern numerical solvers for a series of problems with known exact solutions. The emphasis is placed on investigation of solution accuracy by considered artificial neural systems for 13.5 nm and 11.2 nm wavelengths. Numerical experiments on realistic 2D and 3D masks demonstrate that PINNs and neural operators achieve competitive accuracy and significantly reduced prediction times, with the proposed WGNO architecture reaching state-of-the-art performance. The presented neural operator has pronounced generalizing properties, meaning that for unseen problem parameters it delivers a solution accuracy close to that for parameters seen in the training
dataset. These results provide a highly efficient solution for accelerating the design and optimization workflows of next-generation lithography masks.
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Geophysics
A Data-Constrained Framework for Marine Biogeochemistry Modeling with Applications to the Paranaguá Estuarine Complex
Leticia Becher
Marine biogeochemical models are widely used to study nutrient dynamics, water quality, and
climate-related processes in coastal and estuarine systems. However, developing models that reliably represent specific environments remains computationally demanding, which makes their application to complex systems such as river plumes and estuarine environments challenging. In addition, these models contain several parameters that must be calibrated for the region of interest, a process that is often performed empirically using limited observational data. This thesis advances the development and calibration of marine biogeochemical models in the Brazilian context through three main contributions. First, we develop a conceptual model describing nutrient-phytoplankton dynamics in the Paranagua Estuarine Complex (PEC) in southern Brazil. The model is intentionally simple and computationally inexpensive, allowing simulations to be performed on standard personal computers. Second, we propose a systematic calibration framework based on tracer
datasets and derivative-free optimization techniques. Finally, we demonstrate the practical application of this approach by calibrating the PEC model using in situ observations. Results show that, despite its simplicity, the model can reproduce observed nutrient dynamics when properly calibrated. The proposed framework is general and can be extended to multi-parameter calibration, seasonal parameter variation, and the coupling of biogeochemical models with higher-fidelity hydrodynamic models.
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Fluid Dynamics
Flow configuration and pressure effects on turbulent premixed hydrogen jet flames
T. L. Howarth, T. Lehmann, M. Gauding et al. (+1 more)
Turbulent lean premixed hydrogen jet flames are simulated using direct numerical simulation employing detailed chemistry in both slot and round configurations at various pressures. All cases are simulated at a constant jet Reynolds number ($Re_j = 10000$) and a fixed ratio of characteristic length scales. While normalised macroscopic quantities (e.g., flame length, turbulent flame speed) appear comparable across configurations, fundamental discrepancies are observed that originate from the coupling of large- and small-scale effects. Mean local reactivity ($I_0$) decays monotonically downstream, driven by a decreasing Karlovitz number ($Ka^{*}$); however, this decay is modulated by geometry, with round jets exhibiting a faster decline due to mean negative
curvature. Pressure is identified as a critical small-scale driver, fundamentally altering flame propagation by increasing the sensitivity of displacement speed to local
curvature. At elevated pressures, this sensitivity induces higher flame stretch and accelerates wrinkling near the nozzle, which compounds with geometry-dependent effects, such as the slower decay of mean strain in slot configurations.
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All authors T. L. Howarth, T. Lehmann, M. Gauding, H. Pitsch