History and Philosophy of Physics
Astronomical Methods and Instrumentation in the Islamic World: Past, Present, Future
Armin MAghami Asl and Yaseen Almleaky
From al-Sufi's tenth-century observation of the Andromeda
Galaxy as a "little cloud" to contemporary space missions, Islamic astronomy represents a millennium-spanning tradition of innovation and knowledge. This study traces its trajectory through three phases: the Golden Age (8th to 15th centuries), when scholars such as al-Biruni, al-Battani, and Ibn Sina developed instruments, cataloged the heavens, and refined theories that later influenced Copernicus; a period of decline (late 15th to 17th centuries), shaped by political fragmentation, economic shifts, and the delayed adoption of technologies such as printing and the
telescope; and today's revival, marked by observatory collaborations, Olympiad successes, and emerging space programs in Morocco, Iran, Turkey, the UAE, and Saudi Arabia. This comparative analysis with Chinese and European scientific traditions shows how Islamic astronomy provided a vital link in the global history of science, transmitting mathematical rigor, observational methods, and Arabic
star names that are still used today. The contemporary resurgence signals the potential for renewed contributions to astrophysics, provided that it is supported by regional observatory networks, space-based research initiatives, and educational frameworks that integrate historical heritage with modern computational science.
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Medical Physics
Placental contractions in uncomplicated pregnancies
Louise Dewick, Amy L Turnbull, Kate F Walker et al. (+11 more)
In 2020 we first described placental contractions, and we have now undertaken a study to characterise them and seek features that might automatically separate them from uterine contractions. We recruited 36 healthy pregnant women to undergo
magnetic resonance imaging (MRI) between 29 and 42 weeks of pregnancy in a single-centre, prospective, observational study. Participants had fetal ultrasound to confirm normal growth. Dynamic MRI was acquired for between 15 and 32 minutes using respiratory triggered, multi-slice, single shot, gradient echo, echo planar imaging covering the whole uterus. All participants had a live birth of a healthy baby weighing over the 10th centile for gestational age and none developed any associated conditions of placental dysfunction e.g. pre-eclampsia, or severe maternal or fetal villous malperfusion on placental histopathology. Any visible contractions were recorded for all participants who completed their MRI scan and placental contractions occurred in at least 60% of our healthy pregnant population with a median frequency of approximately 2 per hour, and a median duration of 2.4 minutes. Contractions involving a decrease in placental volume of >10% were classified as either placental or uterine by visual observation. Placental contractions occurred more frequently than uterine contractions (p=0.0061), were associated with a larger increase in the surface area of the uterine wall not covered by the placenta (p=0.0015), placental sphericity (p<0.0001) and longer duration (p=0.0151). All contractions led to an increase in the MRI parameter R2* in the placenta. There was large variation both between participants and between contractions from the same individual, in terms of time course and contractions features, with no apparent change across the gestational age range studied, although the largest fractional volume changes were detected at early gestation.
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All authors Louise Dewick, Amy L Turnbull, Kate F Walker, Nia W Jones, George Hutchinson, Christopher Bradley, Taqwa Ferdous, Aisha Razzaque, Ruizhe Li, Xin Chen, Grazziela Figueredo, Craig Platt, Cesar Peres, Penny Gowland
Optics
Perfectly Matched Metamaterials
Jorge Ruiz-Garcia and Anthony Grbic
Fully harnessing the vast design space enabled by metamaterials to control electromagnetic (EM) fields remains an open problem for researchers. Inverse-design techniques have shown to best exploit the degrees of freedom available in design, resulting in high-performing systems for wireless communications, sensing and analog signal processing. Nonetheless, fundamental yet powerful properties of metamaterials are still to be revealed. In this paper, we introduce the concept of Perfectly Matched Metamaterials (PMMs). PMMs are passive, inhomogeneous media that perform purely refractive field transformations under different excitations. Their advantage lies in their simplicity, reflectionless behavior and suitability for both analytical and numerical design methods. Unlike Transformation Optics, PMM-based designs are devoid of coordinate transformations. Anisotropic unit
cells are configured to control EM fields in a true-time delay manner. Simple analytical designs are reported which demonstrate the broadband capability of PMM devices. Proposed PMMs may find application in wideband beamforming and analog computing, realizing functionalities such as spatial filtering and signal pre-processing.
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Optics
Designing Space-Time Metamaterials: The Central Role of Dispersion Engineering
Sajjad Taravati
Space-time metamaterials are redefining wave engineering by enabling fully dynamic four-dimensional control of electromagnetic fields, allowing simultaneous manipulation of frequency, amplitude, momentum, and propagation direction. This unified functionality moves well beyond reciprocity-breaking mechanisms, marking a fundamental transition from static media to polychromatic, energy-efficient wave processors. This article establishes dispersion engineering as the core design paradigm for these dynamic systems. We show that the dispersion relation, linking frequency and wavenumber, serves as a master blueprint governing exotic wave phenomena such as nonreciprocity, beam splitting, asymmetric frequency conversion, amplification, spatial decomposition, and momentum bandgaps. By analyzing analytical dispersion surfaces and isofrequency contours in subluminal, luminal, and superluminal modulation regimes, we reveal how tailored spatiotemporal modulation orchestrates controlled energy flow among harmonic modes. We further demonstrate how this framework directly informs practical device operation, highlighting advanced implementations including angular-frequency beam multiplexing in superconducting Josephson junction arrays. Combining insights from wave theory, numerical modeling, and experimental realization, this work provides a comprehensive roadmap for leveraging dispersion engineering to design next-generation metamaterials for wireless communication,
quantum technologies, and integrated photonics.
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Atmospheric and Oceanic Physics
PhysDNet: Physics-Guided Decomposition Network of Side-Scan Sonar Imagery
Can Lei, Hayat Rajani, Nuno Gracias et al. (+2 more)
Side-scan sonar (SSS) imagery is widely used for seafloor mapping and
underwater remote sensing, yet the measured intensity is strongly influenced by seabed reflectivity, terrain elevation, and acoustic path loss. This
entanglement makes the imagery highly view-dependent and reduces the robustness of downstream analysis. In this letter, we present PhysDNet, a physics-guided multi-branch network that decouples SSS images into three interpretable fields: seabed reflectivity, terrain elevation, and propagation loss. By
embedding the Lambertian reflection model, PhysDNet reconstructs sonar intensity from these components, enabling self-supervised training without ground-truth annotations. Experiments show that the decomposed representations preserve stable geological structures, capture physically consistent illumination and attenuation, and produce reliable shadow maps. These findings demonstrate that physics-guided decomposition provides a stable and interpretable domain for SSS analysis, improving both physical consistency and downstream tasks such as registration and shadow interpretation.
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All authors Can Lei, Hayat Rajani, Nuno Gracias, Rafael Garcia, Huigang Wang
Optics
Experimental Demonstration of an On-Axis Laser Ranging Interferometer for Future Gravity Missions
Daikang Wei, Christoph Bode, Kohei Yamamoto et al. (+6 more)
We experimentally demonstrate a novel interferometric architecture for next-generation
gravity missions, featuring a
laser ranging interferometer (LRI) that enables monoaxial transmission and reception of
laser beams between two optical benches with a heterodyne frequency of 7.3 MHz. Active beam steering loops, utilizing differential wavefront sensing (DWS) signals, ensure co-
alignment between the receiving (RX) beam and the transmitting (TX) beam. With spacecraft attitude jitter simulated by hexapod-driven rotations, the interferometric link achieves a pointing stability below 10 urad/$\mathrm{\sqrt{Hz}}$ in the frequency range between 0.2 mHz and 0.5 Hz, and the fluctuation of the TX beam's polarization state results in a reduction of 0.14% in the carrier-to-noise-density ratio over a 15-hour continuous measurement. Additionally, tilt-to-length (TTL) coupling is experimentally investigated using the periodic scanning of the hexapod. Experimental results show that the on-axis LRI enables the inter-spacecraft ranging measurements with nanometer accuracy, making it a potential candidate for future GRACE-like missions.
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All authors Daikang Wei, Christoph Bode, Kohei Yamamoto, Yongho Lee, Germán Fernández Barranco, Vitali Müller, Miguel Dovale Álvarez, Juan José Esteban Delgado, Gerhard Heinzel
Biological Physics
Modeling Bioelectric State Transitions in Glial Cells: An ASAL-Inspired Computational Approach to Glioblastoma Initiation
Wiktoria Agata Pawlak
Understanding how glioblastoma (GBM) emerges from initially healthy glial tissue requires models that integrate bioelectrical, metabolic, and multicellular dynamics. This work introduces an ASAL-inspired
agent-based framework that simulates bioelectric state transitions in glial
cells as a function of mitochondrial efficiency (Meff), ion-channel conductances, gap-junction coupling, and ROS dynamics. Using a 64x64 multicellular grid over 60,000 simulation steps, we show that reducing Meff below a critical threshold (~0.6) drives sustained depolarization, ATP collapse, and elevated ROS, reproducing key electrophysiological signatures associated with GBM. We further apply evolutionary optimization (genetic
algorithms and MAP-Elites) to explore resilience, parameter sensitivity, and the emergence of tumor-like attractors. Early evolutionary runs converge toward depolarized, ROS-dominated regimes characterized by weakened electrical coupling and altered ionic transport. These results highlight mitochondrial dysfunction and disrupted bioelectric signaling as sufficient drivers of malignant-like transitions and provide a computational basis for probing the bioelectrical origins of oncogenesis.
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Applied Physics
Robotic chip-scale nanofabrication for superior consistency
Felix M. Mayor, Wenyan Guan, Erik Szakiel et al. (+2 more)
Unlike the rigid, high-volume automation found in industry, academic research requires process flexibility that has historically relied on variable manual operations. This hinders the fabrication of advanced, complex devices. We propose to address this gap by automating these low-volume, high-stakes tasks using a robotic arm to improve process control and consistency. As a proof of concept, we deploy this system for the resist development of Josephson junction devices. A statistical comparison of the process repeatability shows the robotic process achieves a resistance spread across chips close to 2%, a significant improvement over the ~7% spread observed from human operators, validating robotics as a solution to eliminate operator-dependent variability and a path towards industrial-level consistency in a research setting.
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All authors Felix M. Mayor, Wenyan Guan, Erik Szakiel, Amir H. Safavi-Naeini, Samuel Gyger
Atmospheric and Oceanic Physics · Cross-listed from cs.CV
Cloud4D: Estimating Cloud Properties at a High Spatial and Temporal Resolution
Jacob Lin, Edward Gryspeerdt and Ronald Clark
There has been great progress in improving numerical weather prediction and
climate models using machine learning. However, most global models act at a kilometer-scale, making it challenging to model individual clouds and factors such as extreme precipitation, wind gusts,
turbulence, and surface irradiance. Therefore, there is a need to move towards higher-resolution models, which in turn require high-resolution real-world observations that current instruments struggle to obtain. We present Cloud4D, the first learning-based framework that reconstructs a physically consistent, four-dimensional cloud state using only synchronized ground-based cameras. Leveraging a homography-guided 2D-to-3D
transformer, Cloud4D infers the full 3D distribution of
liquid water content at 25 m spatial and 5 s temporal resolution. By tracking the 3D
liquid water content
retrievals over time, Cloud4D additionally estimates horizontal wind vectors. Across a two-month deployment comprising six skyward cameras, our system delivers an order-of-magnitude improvement in space-time resolution relative to state-of-the-art satellite measurements, while retaining single-digit relative error ($<10\%$) against collocated radar measurements. Code and data are available on our project page https://cloud4d.jacob-lin.com/.
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Atomic Physics
Puzzling Isotonic Odd-Even Staggering of Charge Radii in Deformed Rare Earth Nuclei
Endre Takacs, Hunter Staiger, Steven A. Blundell et al. (+16 more)
The
nuclear charge radius is a fundamental observable that encodes key aspects of
nuclear structure, deformation, and pairing. Isotonic (constant
neutron number) systematics in the deformed rare-earth region have long suggested that odd-$Z$
nuclei are more compact than their even-$Z$ neighbors - except for Lu, whose recommended radius appeared anomalously large relative to Yb and Hf. We report a high-precision determination of the natural-abundance-averaged Lu-Yb charge-radius difference using extreme-ultraviolet spectroscopy of highly charged Na-like and Mg-like ions, supported by high-accuracy relativistic atomic-structure calculations - a recently introduced method with the unique ability to measure inter-element charge radius differences. Combined with muonic-atom and optical isotope-shift data, our result resolves the longstanding Lu inversion anomaly and reestablishes a pronounced odd-even staggering along the $N=94$ isotonic chain. The magnitude of this staggering is unexpectedly large, far exceeding that observed in semi-magic
nuclei and in deformed isotopic sequences. State-of-the-art
nuclear density functional theory calculations, including quantified uncertainties, fail to reproduce this enhancement, possibly indicating missing structural effects in current models. Our work demonstrates the power of highly charged ions for precise, element-crossing charge-radius measurements and provides stringent new constraints for future theoretical and experimental studies of
nuclear-size systematics.
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All authors Endre Takacs, Hunter Staiger, Steven A. Blundell, Naoki Kimura, Hiroyuki A. Sakaue, Ronald F. Garcia Ruiz, Witold Nazarewicz, Paul-Gerhard Reinhard, Chowdhury A. Faiyaz, Chihiro Suzuki, Dipti, István Angeli, Yuri Ralchenko, Izumi Murakami, Daiji Kato, Yuki Nagai, Ryuji Takaoka, Yoshiki Miya, Nobuyuki Nakamura
Computational Physics · Cross-listed from astro-ph.HE
Guesswork in the gap: the impact of uncertainty in the compact binary population on source classification
Utkarsh Mali and Reed Essick
The nature of the compact objects within the supposed "lower mass gap" remains uncertain. Observations of GW190814 and GW230529 highlight the challenges gravitational waves face in distinguishing
neutron stars from black holes. Interpreting these systems is especially difficult because classifications depend simultaneously on measurement noise, compact binary population models, and equation of state (EOS) constraints on the maximum
neutron star mass. We analyze 66 confident events from GWTC-3 to quantify how the probability of a component being a
neutron star, P(NS), varies across the population. The effects are substantial, the dominant drivers of classification are the pairing preferences of
neutron stars with other compact objects, and the
neutron star spin distributions. The data reveals that P(NS) varies between 1% - 67% for GW230529's primary and between 51% - 100% for GW190425's primary. By contrast, P(NS) for GW190814's secondary varies by <10%, demonstrating robustness from its high signal-to-noise ratio and small mass ratio. Analysis using EOS information tends to affect P(NS) through the inferred maximum
neutron star mass rather than the maximum
spin. As it stands, P(NS) remains sensitive to numerous population parameters, limiting its reliability and potentially leading to ambiguous classifications of future GW events.
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Fluid Dynamics
Realistic sheared flow profile effects on acoustic impedance eduction in small 3D-ducts
Lucas A. Bonomo, Julio A. Cordioli, Edward J. Brambley et al. (+2 more)
We investigate the influence of realistic sheared grazing flow on acoustic propagation in three-dimensional rectangular ducts. We show that conclusions reached in the literature about the effects of sheared grazing flow on acoustic propagation in lined ducts are dependent on the flow profiles used in those studies, and that significantly different conclusions are reached once a realistic flow profile is used. We particularly focus on small ducts typical of most experimental impedance eduction facilities, for which velocity gradients are relevant in a significant fraction of the duct cross-section. We assess the effect of simplifying the velocity distribution in the cross-section to either a one-dimensional (2D spanwise-infinite duct) or uniform flow profile. Three flow profiles are considered, namely (i) the tensorised
hyperbolic tangent, (ii) the law of the wall, and (iii) one obtained from a RANS simulation. These flow profiles are used as input in numerical simulations, based on the solution of the 3D Pridmore-Brown equation, to perform in silico impedance eduction experiments. Results show that realistic flow profiles can be well approximated for acoustic wave propagation in ducts by uniform or 1D flow profiles, provided the bulk Mach number is correctly accounted for, which contrasts with previous findings based on more simplistic flow profiles. The key conclusion of this work is that, if viscous effects are negligible and acoustic impedance is a good representation of a lined wall with grazing flow, then the simplification to a uniform flow is a reasonable approximation and traditional eduction methods are sufficiently accurate.
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All authors Lucas A. Bonomo, Julio A. Cordioli, Edward J. Brambley, Angelo Paduano, Francesco Avallone
Chemical Physics · Cross-listed from cond-mat.mtrl-sci
Artificial Intelligence Driven Workflow for Accelerating Design of Novel Photosensitizers
Hongyi Wang, Xiuli Zheng, Weimin Liu et al. (+2 more)
The discovery of high-performance photosensitizers has long been hindered by the time-consuming and resource-intensive nature of traditional trial-and-error approaches. Here, we present AI-Accelerated PhotoSensitizer Innovation (AAPSI), a closed-loop workflow that integrates expert knowledge, scaffold-based molecule generation, and
Bayesian optimization to accelerate the design of novel photosensitizers. The scaffold-driven generation in AAPSI ensures structural novelty and synthetic feasibility, while the iterative AI-experiment loop accelerates the discovery of novel photosensitizers. AAPSI leverages a curated database of 102,534 photosensitizer-solvent pairs and generate 6,148 synthetically accessible candidates. These candidates are screened via graph
transformers trained to predict singlet oxygen
quantum yield ($\phi_\Delta$) and absorption maxima ($\lambda_{max}$), following experimental validation. This work generates several novel candidates for photodynamic therapy (PDT), among which the hypocrellin-based candidate HB4Ph exhibits exceptional performance at the Pareto frontier of high
quantum yield of singlet oxygen and long absorption maxima among current photosensitizers ($\phi_\Delta$=0.85, $\lambda_{max}$=650nm).
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All authors Hongyi Wang, Xiuli Zheng, Weimin Liu, Zitian Tang, Sheng Gong
Computational Physics
Electrified Metal-Water Interfaces at Constant Potential: Data-Efficient Transfer Learning for Machine-Learning-Based Molecular Dynamics
Michele Giovanni Bianchi, Michele Re Fiorentin, Francesca Risplendi et al. (+4 more)
Simulating electrified metal-water interfaces with explicit solvent under constant potential is essential for understanding electrochemical processes, yet remains prohibitively expensive with ab initio methods. We present TRECI, a data-efficient workflow for constructing machine learning force-fields (ML-FFs) that achieve ab initio-level accuracy in electronically grand-canonical molecular dynamics. By leveraging transfer learning from general-purpose and domain-specific models, TRECI enables stable and accurate simulations across a wide potential range using a reduced number of reference configurations. This efficiency allows the use of high-level meta-GGA functionals and rigorous surface-electrification schemes. Applied to Cu(111)-water, models trained on just one thousand configurations yield accurate molecular dynamics simulations, capturing bias-dependent solvent restructuring effects not previously reported. TRECI offers a general strategy for characterising diverse materials and interfacial chemistries, significantly lowering the cost of realistic constant-potential simulations and expanding access to quantitative electrochemical modelling.
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All authors Michele Giovanni Bianchi, Michele Re Fiorentin, Francesca Risplendi, Candido Fabrizio Pirri, Michele Parrinello, Luigi Bonati, Giancarlo Cicero
Medical Physics
A primer on treatment planning aspects for temporally modulated pulsed radiation therapy
Christian Velten, Adam Bayliss, Jiayi Huang et al. (+1 more)
Temporally modulated pulsed radiotherapy (TMPRT) delivers conventional fraction doses of radiation using temporally separated pulses of low doses (<30 cGy) yielding fraction-effective dose rates of around 6.7 cGy/min with the goal to exploit tumor radiation hypersensitivity, which was observed in both, preclinical models and in human clinical trials. To facilitate TMPRT, volumetric modulated arc therapy (VMAT) and 3D-CRT planning techniques were developed following the guidelines of the proposed NRG CC-017 trial. Plans were evaluated with respect to homogeneity, conformality, and adherence to dose constraints. Deliverability of plans was assessed using in-phantom measurements for absorbed dose accuracy at low dose rates and using EPID for isodose verification. For VMAT only single arc plans were found to be acceptable due to otherwise unacceptably heterogeneous field doses, while for dynamic conformal arcs machine limtations on the number of monitor units per degree require the use of partial arcs for each pulse. Delivery of plans at low dose rates (< 100 MU/min) was accurate with high Gamma pass rates on modern LINACs and moderate pass rates on legacy LINACs, in line with their general performance. Generally, VMAT is preferred to achieve optimal homogeneity, conformality, and organ-at-risk sparing, while the use of 3D-CRT can increase the availability of TMPRT for more patients and clinics.
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All authors Christian Velten, Adam Bayliss, Jiayi Huang, Wolfgang A. Tomé
Optics
Scattering in Time-Varying Drude-Lorentz Models
Bryce Dixon, Calvin M. Hooper, Ian R. Hooper et al. (+1 more)
Motivated by recent experiments, the theoretical study of wave propagation in time varying materials is of current interest. Although significant in nearly all such experiments, material dispersion is commonly neglected in theoretical studies. Yet, as we show here, understanding the precise microscopic model for the material dispersion is crucial for predicting experimental outcomes. Here we study the temporal scattering coefficients of four different time-varying Drude-Lorentz models, exploring how an incident continuous wave splits into forward and backward waves due to an abrupt change in
plasma frequency. The differences in the predicted scattering are unique to time-varying media, and arise from the exact way in which the time variation appears in the various model parameters. We verify our results using a custom finite difference time domain
algorithm, concluding with a discussion of the limitations that arise from using these models with an abrupt change in
plasma frequency.
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All authors Bryce Dixon, Calvin M. Hooper, Ian R. Hooper, Simon A. R. Horsley
Atomic Physics
Multiphoton ionization with three-dimensional light fields
Darius Köhnke, Hans-Christian Ahlswede, Tim Bayer et al. (+1 more)
We report the first observation of free-electron angular momentum wave packets generated by atomic multiphoton ionization with bichromatic three-dimensional (3D) polarization-tailored ultrashort
laser fields. These fields, created by the non-collinear superposition of two polarization-shaped pulses of different colors from a supercontinuum polarization pulse shaper, provide electric-field components along all spatial directions. The resulting photoelectron momentum distributions, recorded via velocity map imaging, demonstrate full 3D coherent control of electronic superposition states extending beyond the constraints of planar polarization fields by unlocking all dipole selection rules $\Delta m = 0,\pm1$. As an application, 3D pump-probe fields are used to image previously unobserved photoelectron wave packets mapping
spin-orbit dynamics of the potassium $3d$ fine structure doublet. Our shaper-based approach establishes a route to fully controllable 3D light fields for
chiral-sensitive light-matter interactions and ultrafast spectroscopy.
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All authors Darius Köhnke, Hans-Christian Ahlswede, Tim Bayer, Matthias Wollenhaupt
Plasma Physics
Two-Stream Instability and Bernstein-Greene-Kruskal Mode Formation in Coulomb One Component Plasma
Ajaz Mir, Rauoof Wani, Sanat Tiwari et al. (+1 more)
We investigate the Two-Stream Instability in a strongly coupled
plasma using classical molecular dynamics simulations with long-range Coulomb interactions between particles. The nonlinear
evolution of the instability is identified by the emergence of a Bernstein-Greene-Kruskal (BGK) mode. Our simulations capture key microscopic effects, such as inter-particle correlations, collisional dynamics, and coherent wave-particle interactions-features often absent in traditional fluid and kinetic models, including Particle-In-
Cell and Vlasov approaches. In the linear regime, the instability grows rapidly and saturates within a few tens of
plasma periods. As the system transitions into the nonlinear saturation phase, a single BGK mode emerges. This mode (or phase-space hole) becomes dynamically unstable in the nonlinear regime, characterized by a continuous decay of electrostatic energy over time. An energy budget analysis reveals a bump in an otherwise thermal spectrum, indicating the excitation of a coherent mode, further confirmed through a numerical rendering of the dispersion relation. The pairwise interaction plays a crucial role: pronounced instability and BGK mode formation occur with long-range Coulomb forces, while such structures are suppressed under shielded Coulomb interactions. We observe the emergence of a single BGK mode across all coupling strengths in the fluid regime, provided the streaming velocity exceeds a critical threshold.
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All authors Ajaz Mir, Rauoof Wani, Sanat Tiwari, Abhijit Sen
History and Philosophy of Physics · Cross-listed from quant-ph
A demonstration that classical gravity does not produce entanglement
Mike D. Schneider, Nick Huggett and Niels Linnemann
Once again, dispute has arisen over the interpretation of proposed
quantum information theory experiments to probe the
quantum nature of
gravity by testing for gravitationally induced
entanglement (GIE) between two spatially separated massive particles ([2] vs. [16, 17]; further contributions in [11, 13]). The confusion appears to reside in interpreting applications of a
Hamiltonian formalism. But classical
gravity cannot mediate
entanglement on independent grounds. A Newton-Cartan analysis shows that if
gravity is classical, a mediator, and
entanglement is observed as an outcome of performing a GIE experiment, something other than
gravity must have supplied the (virtual) force needed during the experiment to produce the effect.
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Optics
Fast and length-independent transport time supported by topological edge states in finite-size Su-Schrieffer-Heeger chains
Yu-Han Chang, Nadia Daniela Rivera Torres, Santiago Figueroa Manrique et al. (+9 more)
In order to transport information with topological protection, we explore experimentally the fast transport time using edge states in one-dimensional Su-Schrieffer-Heeger (SSH) chains. The transport time is investigated in both one- and two-dimensional models with topological non-trivial band structures. The fast transport is inherited with the wavefunction localization, giving a stronger effective coupling strength between the mode and the measurement leads. Also the transport time in one-dimension is independent of the system size. To verify the asertion, we implement a chain of split-ring resonators and their complementary ones with controllable hopping strengths. By performing the measurements on the group delay of non-trivially topological edge states with pulse excitations, the transport time between two edge states is directly observed with the chain length up to $20$. Along the route to harness
topology to protect optical information, our experimental demonstrations provide a crucial guideline for utilizing photonic topological devices.
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All authors Yu-Han Chang, Nadia Daniela Rivera Torres, Santiago Figueroa Manrique, Raul A. Robles Robles, Vanna Chrismas Silalahi, Cen-Shawn Wu, Gang Wang, Giulia Marcucci, Laura Pilozzi, Claudio Conti, Ray-Kuang Lee, Watson Kuo
Accelerator Physics
FPGA-Based Spill Regulation System for the Muon Delivery Ring at Fermilab
J. R. Berlioz, D. Bracey, B. Fellenz et al. (+6 more)
The
Muon to Electron Experiment (Mu2e) requires a uniform beam profile from the
Muon Delivery Ring to meet their experimental needs. A specialized Spill Regulation System (SRS) has been developed to help achieve consistent spill uniformity. The system is based on a custom-designed carrier board featuring an Arria 10 SoC, capable of executing real-time feedback control. The FPGA processes beam pulses of approximately 200 ns every 1.695 ${\mu}$s, allowing for continuous monitoring of the extracted spill intensity through fast bunch integration. The system directly controls three quadrupole magnets, which work in conjunction with sextupole magnets to achieve third-order resonant extraction. Furthermore, the board interfaces with Fermilab's Accelerator Control Network (ACNET), enabling operators to modify spill regulation settings in real-time via the control network while providing diagnostic waveforms. These waveforms help operators monitor the process and fine-tune the feedback mechanisms. This paper presents an overview of the board's architecture and its initial progress toward regulating beam extraction. This initial version of the regulation system aims to evaluate baseline performance to inform future system improvements.
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All authors J. R. Berlioz, D. Bracey, B. Fellenz, M. A. Ibrahim, V. Nagaslaev, A. Narayanan, P. Prieto, K. Danison-Fieldhouse, W. Sullivan
Medical Physics
In-vivo imaging with a low-cost MRI scanner and cloud data processing in low-resource settings
Teresa Guallart-Naval, Robert Asiimwe, Patricia Tusiime et al. (+16 more)
Purpose: To demonstrate in-vivo imaging with a low-cost, low-field MRI scanner built and operated in Africa, and to show how systematic hardware and software improvements can mitigate the main operational limitations encountered in low-resource environments. Methods: A 46 mT Halbach scanner located at the Mbarara University of Science and Technology (Uganda) was upgraded through a complete reorganization of grounding and shielding, installation of new control electronics and open-source user-interface software. Noise performance was quantified using a standardized protocol and in-vivo
brain images were acquired with three-dimensional RARE sequences. Distortion correction was implemented using cloud-based reconstructions incorporating
magnetic field maps. Results: The revamped system reached noise levels routinely below three times the thermal limit and demonstrated stable operation over multi-day measurements. Three-dimensional T1- and T2-weighted
brain images were successfully acquired and distortion-corrected with remote GPU-based reconstructions and near real-time visualization through the user interface. Conclusions: The results show that low-cost MRI systems can achieve clinically relevant image quality when electromagnetic noise and power-grid instabilities are properly addressed. This work highlights the feasibility of sustainable MRI development in low-resource settings and identifies stable power delivery and local capacity building as the key next steps toward clinical translation.
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All authors Teresa Guallart-Naval, Robert Asiimwe, Patricia Tusiime, Mary A. Nassejje, Leo Kinyera, Lemi Robin, Maureen Nayebare, Luiz G. C. Santos, Marina Fernández-García, Lucas Swistunow, José M. Algarín, John Stairs, Michael Hansen, Ronald Amodoi, Andrew Webb, Joshua Harper, Steven J. Schiff, Johnes Obungoloch, Joseba Alonso
Data Analysis and Statistics · Cross-listed from astro-ph.GA
Inclinations and Position Angles for Disc Galaxies in the SGA sample
Megan H. Martinez, Michael S. Petersen, Carrie Filion et al. (+2 more)
We present a data-driven method for determining the inclination and position angle (PA) of disc
galaxies using a
Fourier-Laguerre basis decomposition of imaging data. We define a dimensionless metric, $\eta$, that characterises the ratio of the quadrupole and monopole coefficients in the
Fourier-Laguerre basis function expansion. This metric serves as a robust measure which is related to the inclination of a
galaxy. We find an empirical relationship between $\eta$ and inclination which is agnostic to the
galaxy morphology. The PA is derived directly from the phase of the quadrupolar
Fourier-Laguerre functions. Across a
benchmark sample of
galaxies, the method reproduces published inclination and PA values to within a median of 10$^\circ$ and 5$^\circ$, respectively, while also demonstrating essentially zero catastrophic failures. Applying this pipeline to
galaxies from the Siena
Galaxy Atlas (SGA), we report measurements of $\eta$, scale length and PA for three different bands of 133,942 disc
galaxies. Our computationally inexpensive technique automates parametrisation analysis and returns reproducible results for large surveys. We release a Python package ready for application to next generation surveys.
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All authors Megan H. Martinez, Michael S. Petersen, Carrie Filion, Rashid Yaaqib, Claire Larson
Instrumentation and Detectors
Insights into neutron transport in a new multipurpose nuclear reactor
Luiz Paulo de Oliveira, Alexandre Pinho dos Santos Souza, Carlos Gabriel da Silva Santos et al. (+4 more)
Neutron transport inside the reflector tank of the new Brazilian
nuclear reactor, called the RMB (Brazilian Multipurpose Reactor), is investigated using the
stochastic Monte Carlo method. One of the main characteristics of research
nuclear reactors is the core power density, which is proportional to the
neutron flux generated in the fission reaction. The RMB is part of the new generation of multipurpose reactors, and studying
neutron transport is essential for the project to meet its objectives of producing radioisotopes, irradiating materials, and generating
neutron beams for scientific investigations. The
neutron moderation process in the reflector tank is very well described by Maxwellian distributions, which provide temperatures ranging from T = 331.5 K in the core to T = 266.8 K in the peripheral regions. The relative proportions reveal the predominance (52%) of epithermal
neutrons in the reactor core, followed by thermal (29%) and fast (19%)
neutrons. The moderation process proves to be effective, considering that 100% of the
neutrons fall within the thermal spectrum near the reflector tank wall. The fits using Maxwellian distributions reveal another effect of
neutron moderation, a shift in the peak wavelength from 1.07 Å to 1.19 Å. The same effect is observed along the tube that supplies a
neutron beam to the RMB imaging instrument, with $\lambda_{peak}$ = 1.18 Å increasing to $\lambda_{peak}$ = 1.21 Å.
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All authors Luiz Paulo de Oliveira, Alexandre Pinho dos Santos Souza, Carlos Gabriel da Silva Santos, Iberê Souza Ribeiro Júnior, Barbara Perez Gonçalves Silva, Marco Antonio Stanojev Pereira, Frederico Antonio Genezini
Geophysics
A Deep-Learning-Based Framework for Focal Mechanism Determination and Its Application to the 2022 Luding Earthquake Sequence
Ziye Yu and Yuqi Cai
P-wave first-motion polarity plays an important role in resolving focal mechanisms of small to moderate earthquakes (M <= 4.5). High-quality focal mechanism solutions for abundant small events can greatly improve our understanding of regional tectonics, fault geometries, and stress-field characteristics. In this study, we develop an automated focal mechanism determination framework that integrates deep neural networks with P-wave first-motion polarity observations, and apply it to the 2022 Luding earthquake sequence. The model is trained on 12 years (2009-2020) of manually annotated 100 Hz waveform records from the China National Seismic Network, achieving a polarity recall of 97.4 percent and a precision of 98.5 percent. After automatically determining the first-motion polarities, we invert focal mechanisms using the HASH method. The resulting focal mechanism solutions show high consistency with mapped fault structures in the Luding region, demonstrating the reliability and applicability of the proposed workflow.
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Physics and Society
Decarbonization pathways for liquid fuels: A multi-sector energy system perspective
Jun Wen Law, Bryan K. Mignone and Dharik S. Mallapragada
Low-carbon
liquid fuels play a key role in energy system decarbonization scenarios. This study uses a multi-sector capacity expansion model of the contiguous United States to examine fuels production in deeply decarbonized energy systems. Our analysis evaluates how the shares of biofuels, synthetic fuels, and fossil
liquid fuels change under varying assumptions about resource constraints (biomass and CO2 sequestration availability), fuel demand distributions, and supply flexibility to produce different fuel products. Across all scenarios examined, biofuels provide a substantial share of
liquid fuel supply, while synthetic fuels deploy only when biomass or CO2 sequestration is assumed to be more limited. Fossil
liquid fuels remain in all scenarios examined, primarily driven by the extent to which their emissions can be offset with removals. Limiting biomass increases biogenic CO2 capture within biofuel pathways, while limiting sequestration availability increases the share of captured atmospheric (including biogenic) carbon directed toward utilization for synthetic fuel production. While varying assumptions about
liquid fuel demand distributions and fuel product supply flexibility alter competition among individual fuel production technologies, broader energy system outcomes are robust to these assumptions. Biomass and CO2 sequestration availability are key drivers of energy system outcomes in deeply decarbonized energy systems.
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Instrumentation and Detectors
Approximate resolution convolution function for fitting a dispersion gap measured on a triple-axis spectrometer
Emma Y. Lenander, Silas B. Schack, Kim Lefmann et al. (+1 more)
We present an analytic convoluted-gap function, eq. 11 in the manuscript, for fitting dispersion gaps measured on triple-axis spectrometers (TAS). At the gap, the instrumental resolution skews the signal, producing a high-energy tail that complicates fitting. Our function assumes an instrumental $Q$-resolution with two equal wide and one narrow direction (typical of focused TAS instruments), and a
parabolic dispersion at the gap, which is exact for quadratic and accurate for linear dispersions if the resolution is moderate. We demonstrate, that our function outperforms previous methods of fitting a gap, by giving a better fit and more accurate gap determination, seen in figure 4. Here, the anti-ferromagnetically gapped material; MnF$_2$ is simulated in a double-focusing TAS instrument. We also tested our function on experimental data on MnF$_2$ from a TAS-like instrument, where we reproduce the gap size from previous accurate experimentally determined measurements. The function is simple to implement, converges reliably, and we recommend its use for future gap fitting on TAS data.
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All authors Emma Y. Lenander, Silas B. Schack, Kim Lefmann, Henrik M. Rønnow
Accelerator Physics
Automated RF Phase Adjustment for Beam Stabilization in the Fermilab Linac
R. R. Chichili, J. A. Sulskis, R. Sharankova et al. (+2 more)
The Fermilab Linac experiences longitudinal beam phase drift, leading to increased particle loss, conventionally corrected through labor-intensive manual RF adjustments. This project explores machine learning-based automation for drift correction, employing a prototype-based classification approach. Our model utilizes a 34-dimensional feature set (RF settings and BPM readings) and leverages a 7x27 response
matrix for system modeling. To overcome limited real-world data, we generate synthetic data, enhancing model training and generalizability. Custom loss functions, including a surrogate energy-consistent loss and a temporal smoothness constraint, ensure physically plausible drift predictions. The goal is a robust system for autonomous phase adjustments, ensuring stable beam acceleration and reduced manual intervention.
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All authors R. R. Chichili, J. A. Sulskis, R. Sharankova, B.Vamanan, S. Ravi
Plasma Physics
Abnormal Polarity Effect on the DC Breakdown Voltage in Short SF6 Gap
Zihao Feng
In this Letter, through the comparison between experiment and numerical simulation, we reveal the dynamic mechanism underlying the abnormal polarity effect in SF6 short-gap DC breakdown, as well as a novel criterion for predicting negative breakdown voltage. Using the traditional single-streamer breakdown criterion, the simulated positive breakdown voltage agrees well with experimental measurements, whereas the simulated negative breakdown voltage deviates markedly from the experiments, so the single-streamer breakdown criterion fails to reproduce the abnormal polarity effect observed experimentally. In addressing this, we propose an ion-ion
plasma breakdown criterion for negative breakdown voltage. When this novel criterion is applied, the simulated negative breakdown voltage agrees with the experiments and reflects the abnormal polarity effect. Analysis of the spatiotemporal
evolution of key physical parameters reveals that, the dynamic mechanism for ion-ion
plasma breakdown for negative polarity can be divided into four stages: primary streamer stage, ion accumulation stage, reconstructive ionization stage, and ion-ion
plasma propagation stage. Notably, the ion-ion
plasma propagation stage is dominated by photoionization-driven negative-ion accumulation rather than conventional impact ionization.
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Optics · Cross-listed from cs.CV
3M-TI: High-Quality Mobile Thermal Imaging via Calibration-free Multi-Camera Cross-Modal Diffusion
Minchong Chen, Xiaoyun Yuan, Junzhe Wan et al. (+2 more)
The miniaturization of thermal sensors for mobile platforms inherently limits their spatial resolution and textural fidelity, leading to blurry and less informative images. Existing thermal super-resolution (SR) methods can be grouped into single-image and RGB-guided approaches: the former struggles to recover fine structures from limited information, while the latter relies on accurate and laborious cross-camera calibration, which hinders practical deployment and robustness. Here, we propose 3M-TI, a calibration-free Multi-camera cross-Modality
diffusion framework for Mobile Thermal Imaging. At its core, 3M-TI integrates a cross-modal self-
attention module (CSM) into the
diffusion UNet, replacing the original self-
attention layers to adaptively align thermal and RGB features throughout the denoising process, without requiring explicit camera calibration. This design enables the
diffusion network to leverage its generative prior to enhance spatial resolution, structural fidelity, and texture detail in the super-resolved thermal images. Extensive evaluations on real-world mobile thermal cameras and public
benchmarks validate our superior performance, achieving state-of-the-art results in both visual quality and quantitative metrics. More importantly, the thermal images enhanced by 3M-TI lead to substantial gains in critical downstream tasks like object detection and
segmentation, underscoring its practical value for robust mobile thermal perception systems. More materials: https://github.com/work-submit/3MTI.
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All authors Minchong Chen, Xiaoyun Yuan, Junzhe Wan, Jianing Zhang, Jun Zhang