Atmospheric and Oceanic Physics
An Eclipse-Ballooning Study of Shadow Bands During the April 2024 Total Eclipse
Giana Deskevich, Norris Bach, Kristian Borysiak et al. (+16 more)
In this study we searched for shadow bands associated with the total
solar eclipse of April 8, 2024. Our aim was to improve our understanding of their origin. Shadow bands are debated to arise either from atmospheric
turbulence within Earth's planetary boundary layer (PBL) or from a diffraction-interference effect occurring above the atmosphere. To test these theories, high altitude balloons (HABs) equipped with light sensors, similar ground light sensors, radiosondes launched with weather balloons, and an aircraft-mounted light sensor were deployed. Our team was located in Concan, TX, except for the plane which flew to NE Vermont to find clear weather. Unlike Pitt's 2017 HAB study, which detected a 4.5 Hz signal attributed to shadow bands above the PBL and on the ground, no shadow bands were detected above the PBL in Texas or in northeast Vermont, despite the use of improved instrumentation. Cloud cover prevented useful ground based measurements in Texas, limiting our conclusions about the nature of shadow bands. These findings suggest that shadow bands may not always be present or, if they are, may be primarily due to atmospheric
turbulence. The results of this study and Pitt's 2017 study emphasize the need for future work.
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All authors Giana Deskevich, Norris Bach, Kristian Borysiak, Russell J. Clark, Louis W. Coban, Istvan Danko, Luke Docherty, Michael Hatridge, Howard Malc, Boris Mesits, Emma Moran, Mathilda Nilsson, Jeffrey B. Peterson, Edward Michael Potosky, Sandhya M. Rao, Peri Schindelheim, James D. Turnshek, Ameya Velankar, Ryan Young David A. Turnshek
Applied Physics
Optimization of Packed-Bed Energy Storage Systems Based on a Second Law Analysis
Y. Jin, E. Makhova and A. Speerforck
Packed-bed sensible heat storage (SHS) is important for balancing energy supply and demand over time. To improve the efficiency of a packed-bed SHS system through second law analysis (SLA), we developed macroscopic
entropy and exergy transport equations for fluid flow and heat transfer in porous media based on microscopic transport equations. These equations enable us to identify where and how much exergy is destroyed. Using a packed-bed SHS system developed at the PROMES-CNRS laboratory as a test case, we demonstrated how to apply SLA to optimize an SHS system. Our analysis revealed that, in addition to exit and heat leakage losses at tank surfaces, thermal and solid conduction losses inside the tank significantly contribute to total loss in the studied SHS system. These internal losses occur close to the thermocline. However, their slower transport causes a delay in their emergence. The SLA suggests an optimal tank aspect ratio of D/H = 0.75, at which the total exergy loss coefficient reaches its minimum value when exit loss is not considered. As particle size decreases, the exergy loss coefficient also decreases due to enhanced heat transfer between the fluid and solid phases. The pressure loss for the studied SHS system is negligible. The SLA favors a truncated cone-shaped tank with a slightly larger upper surface. Through the SLA, the exergy loss coefficient is reduced from 4.9% for the original design to 4.1% for the optimized design. This study demonstrates that, when used in conjunction with energy analysis, the SLA is an effective tool for optimizing energy storage systems.
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Physics Education
AMACA: Astronomy education with a Multi-sensory, Accessible, and Circular Approach
Rachele Toniolo, Anita Zanella, Andrea Cottinelli et al. (+4 more)
The AMACA project (Astronomy education with a Multi-sensory, Accessible, and Circular Approach) develops multi-sensory activities for accessible education and engagement in astronomy. Despite promising innovations, existing resources are often poorly documented, designed for one-time events, expensive, and lack interdisciplinary collaboration, user testing, and broad dissemination. AMACA addresses these challenges by creating multi-sensory activities for education and outreach, with a particular focus on accessibility for people with sensory disabilities. A circular approach informs its educational structure: (1) a PhD course on multi-sensory astronomy outreach develops hands-on activities with the support of astronomers, psychologists, and organizations for the visually impaired and the deaf; (2) PhD candidates teach High School (HS) students how to deliver the activities; (3) HS students lead the activities at the Astronomy Festival "The Universe in All Senses"; (4) HS students train teachers to implement the activities in their classrooms. AMACA also develops tools to guide project development and track participants' learning. Key findings show improved communication and accessibility awareness among PhD candidates, increased emotional engagement with astronomy among HS students, enhanced public engagement with research and accessibility awareness, and high teacher satisfaction with the flipped-roles, hands-on approach. Overall, AMACA enhances accessibility and engagement in astronomy education across audiences.
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All authors Rachele Toniolo, Anita Zanella, Andrea Cottinelli, Giovanni Liuzzi, Sara Ricciardi, Massimo Grassi, Stefano Delle Monache
Computational Physics
Chaotic Dynamics and Bifurcation Analysis of the Hindmarsh-Rose Neuron Model with Blue-Sky Catastrophe under Magnetic Field Influence
Ram Pravesh Yadav, Hirdesh K. Pharasi, R. K. Brojen Singh et al. (+1 more)
We investigate the impact of
magnetic-field-induced feedback on the dynamics of a Hindmarsh-Rose
neuron model exhibiting a blue-sky catastrophe. By introducing a
magnetic flux variable that couples nonlinearly to the membrane potential, we demonstrate that electromagnetic effects profoundly reshape neuronal firing patterns and bifurcation structure. Interspike-interval bifurcation analysis reveals a nonmonotonic dependence on the
magnetic coupling strength, with weak coupling preserving regular spiking and bursting, intermediate coupling promoting chaotic bursting, and strong coupling yielding structured irregular dynamics. These transitions are quantitatively characterized using the largest Lyapunov exponent computed via the Wolf
algorithm and supported by Poincaré sections and time-series analysis. Our results establish electromagnetic feedback as a robust and tunable mechanism for controlling instability and chaos in slow-fast neuronal systems.
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All authors Ram Pravesh Yadav, Hirdesh K. Pharasi, R. K. Brojen Singh, Anirban Chakraborti
Optics
Multilayer Q-BIC-like Optical Filters with High Throughput Direct-Write Multilayer Lithography
A. Bilgehan Baspinar, Phillippe Pearson and Andrei Faraon
Multilayer metasurfaces provide substantially greater spectral design freedom than single-layer devices, yet their implementation in the visible and near-infrared remains limited by the complexity, cost, and low throughput of conventional nanofabrication. Here, we establish a recently proposed direct-write electron-beam lithography approach as a high-throughput fabrication platform for multilayer resonant metasurfaces, based on an antimony precursor that decomposes in situ into high-index antimony sulfide. This method eliminates deposition-etch cycles and reduces each layer to only two fabrication steps, enabling efficient realization of multilayer architectures. Using this platform, we demonstrate multilayer q-BIC-derived metasurfaces with independently tunable resonance wavelengths and linewidths, allowing the construction of compact multi-resonant filters with spectrally decoupled layers. We experimentally demonstrate three-layer devices supporting three resonances and show independent control of resonance wavelength and Q factor across layers. Leveraging this capability, we generate decorrelated filter arrays for compressive sensing and hyperspectral reconstruction, achieving sets of 9 and 36 filters with average absolute Pearson correlation coefficients of 0.11 and 0.21, surpassing prior metasurface and photonic-
crystal implementations. These results establish a practical route toward scalable multilayer resonant metasurfaces for spectral filtering, on-chip spectroscopy, and computational imaging.
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Applied Physics · Cross-listed from cond-mat.mtrl-sci
Rotating Magnetocaloric Effect in First-order Phase Transition Material Gd5Si2Ge2
Rafael Almeida, Rodrigo Kiefe, Ricardo Moura Costa Pinto et al. (+5 more)
The rotating magnetocaloric effect (RMCE) induced by self-demagnetization has been investigated in the
giant magnetocaloric effect (GMCE) material Gd$_5$Si$_2$Ge$_2$. This shape-dependent effect had thus far only been reported in pure Gd, marking this as the first analysis of the effect in a sample with a magnetostructural first-order phase transition. By rotating the applied
magnetic field vector while keeping its intensity constant, the demagnetizing field within a high-aspect ratio sample changes significantly, resulting in a RMCE. We characterize RMCE by determining the adiabatic temperature change ($\Delta T_{ad}^{rot}$) directly through temperature measurements, and the isothermal
entropy change ($\Delta S_M^{rot}$) via magnetometry and magnetostatic simulations. We obtain a remarkable maximum $\Delta T_{ad}^{rot}$ of 1.77 K for a constant external field of 0.8 T, higher than that obtained under 1.0 T. The magnetostatic simulations not only corroborate the highly non-monotonous field-dependence of $|\Delta S_{M}^{rot}|$, which reaches 95% of its maximum value at 0.8 T, 6.12 J K$^{-1}$ kg$^{-1}$ for the experimentally measured shape, but also estimate a 35% increase in the maximum $|\Delta S_{M}^{rot}|$ up to 8.67 J K$^{-1}$ kg$^{-1}$ in a simulated shape with higher aspect ratio.
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All authors Rafael Almeida, Rodrigo Kiefe, Ricardo Moura Costa Pinto, João Sequeira Amaral, Kyle Dixon-Anderson, Yaroslav Mudryk, João Pedro Araújo, João Horta Belo
Fluid Dynamics
Discover the GLM and pseudo-Lagrangian equations of fluid dynamics on four pages
V.A. Vladimirov
The General Lagrangian Mean (GLM) theory uses a set of averaged equations of fluid dynamics to describe interactions between mean flows and waves. These equations are formulated in coordinates that follow the fluid's average velocity and are often referred to as `pseudo-Lagrangian' or `semi-Lagrangian'. This paper focuses on the principles for deriving the pseudo-Lagrangian and GLM equations, using an inviscid, incompressible, homogeneous fluid as a demonstration case. Our exposition differs methodically from that of others and is aimed at the learners of the subject. Keywords: fluid flows, pseudo-Lagrangian description, GLM theory, inviscid incompressible fluid, Lagrangian displacements, mean flows, waves, averaged equations.
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Medical Physics · Cross-listed from eess.IV
Pixelwise Uncertainty Quantification of Accelerated MRI Reconstruction
Ilias I. Giannakopoulos, Lokesh B Gautham Muthukumar, Yvonne W. Lui et al. (+1 more)
Parallel imaging techniques reduce
magnetic resonance imaging (MRI) scan time but image quality degrades as the acceleration factor increases. In clinical practice, conservative acceleration factors are chosen because no mechanism exists to automatically assess the diagnostic quality of undersampled reconstructions. This work introduces a general framework for pixel-wise uncertainty quantification in parallel MRI reconstructions, enabling automatic identification of unreliable regions without access to any ground-truth reference image. Our method integrates conformal
quantile regression with image reconstruction methods to estimate statistically rigorous pixel-wise uncertainty intervals. We trained and evaluated our model on Cartesian undersampled
brain and knee data obtained from the fastMRI
dataset using acceleration factors ranging from 2 to 10. An end-to-end Variational Network was used for image reconstruction. Quantitative experiments demonstrate strong agreement between predicted uncertainty maps and true reconstruction error. Using our method, the corresponding Pearson correlation coefficient was higher than 90% at acceleration levels at and above four-fold; whereas it dropped to less than 70% when the uncertainty was computed using a simpler a heuristic notion (magnitude of the residual). Qualitative examples further show the uncertainty maps based on
quantile regression capture the magnitude and spatial distribution of reconstruction errors across acceleration factors, with regions of elevated uncertainty aligning with pathologies and artifacts. The proposed framework enables evaluation of reconstruction quality without access to fully-sampled ground-truth reference images. It represents a step toward adaptive MRI acquisition protocols that may be able to dynamically balance scan time and diagnostic reliability.
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All authors Ilias I. Giannakopoulos, Lokesh B Gautham Muthukumar, Yvonne W. Lui, Riccardo Lattanzi
Atomic Physics · Cross-listed from cond-mat.quant-gas
Anomalous diffusion and localization in a disorder-free atomic mixture
Stefano Finelli, Beatrice Restivo, Alessio Ciamei et al. (+5 more)
The concept of random walk, in which particles or waves undergo multiple collisions with the microscopic constituents of a surrounding medium, is central to understanding diffusive transport across many research areas. However, this paradigm may break down in complex systems, where
quantum interference and
memory effects render the particle propagation anomalous, often fostering localization. Here we report on the observation of such anomalous dynamics in a minimal setting: an ultracold mass-imbalanced mixture of two fermionic gases in three dimensions. We release light
impurities into a gas of heavier atoms and follow their
evolution across different collisional regimes. Under strong interspecies interactions, by lowering the temperature we unveil a crossover from normal
diffusion to subdiffusion. Simultaneously, a localized fraction of the light gas emerges, displaying no discernible dynamics over hundreds of collisions. Our findings, incompatible with the conventional
Fermi-
liquid picture, are instead captured by a model of an atom propagating through a (quasi-)static disordered landscape of point-like scatterers. These results highlight the key role of
quantum interference in our mixture, which emerges as a versatile platform for exploring disorder-free localization phenomena.
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All authors Stefano Finelli, Beatrice Restivo, Alessio Ciamei, Andreas Trenkwalder, Massimo Inguscio, Dmitry S. Petrov, Sergey E. Skipetrov, Matteo Zaccanti
Applied Physics · Cross-listed from cond-mat.mtrl-sci
Beta-AlGaO/Ga2O3 Tri-Gate MOSHEMT with 70GHz fT and 55GHz fmax
Noor Jahan Nipu, Chinmoy Nath Saha and Uttam Singisetti
We report Beta-AlGaO/Ga2O3 tri-gate
heterostructure MOSHEMTs incorporating a thin 5 nm Al2O3 gate
oxide layer for improved gate control and reduced leakage. The devices were fabricated on AlGaO/GaO
heterostructures grown by ozone MBE on Fe-doped Ga2O3 (010) substrates. The tri-gate MOSHEMTs, with 1 micron-wide fins and Lg=155 nm, exhibit a peak current-gain cut-off frequency fT=70 GHz and a power-gain cut-off frequency fMAX=55 GHz.The fT.L product of 10.85 GHz-micron is the highest among reported Ga2O3 FETs to date. The devices show Vth =-0.5 V, an on/off ratio 10^6 I=80 mA/mm, a peak gm=60 mS/mm, and a low gate leakage current of 10^(-10) mA/mm at Vgs=0.5 V. Passivation with a 100 nm ALD Al2O3 layer effectively removes DC/RF dispersion and maintains stable operation under pulsed IV and repeated RF measurements. These results demonstrate the potential of tri-gate AlGaO/GaO MOSHEMTs for next-generation high-frequency and high-power applications.
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Physics and Society
Modelling viable supply networks with cooperative adaptive financing
Yaniv Proselkov, Liming Xu and Alexandra Brintrup
We propose a financial liquidity policy sharing method for firm-to-firm supply networks, introducing a scalable autonomous control function for viable complex adaptive supply networks. Cooperation and competition in supply chains is reconciled through overlapping collaborative sets, making firms interdependent and enabling distributed risk governance. How cooperative range - visibility - affects viability is studied using dynamic complex adaptive systems modelling. We find that viability needs cooperation; visibility and viability grow together in scale-free supply networks; and distributed control, where firms only have limited partner information, outperforms centralised control. This suggests that policy toward network viability should implement distributed supply chain financial governance, supporting interfirm collaboration, to enable autonomous control.
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Fluid Dynamics · Cross-listed from cs.LG
LAViG-FLOW: Latent Autoregressive Video Generation for Fluid Flow Simulations
Vittoria De Pellegrini and Tariq Alkhalifah
Modeling and
forecasting subsurface multiphase fluid flow fields underpin applications ranging from geological CO2 sequestration (GCS) operations to geothermal production. This is essential for ensuring both operational performance and long-term safety. While high fidelity multiphase simulators are widely used for this purpose, they become prohibitively expensive once many forward runs are required for inversion purposes and to quantify uncertainty. To tackle this challenge, we propose LAViG-FLOW, a latent autoregressive
video generation
diffusion framework that explicitly learns the coupled
evolution of saturation and pressure fields. Each state variable is compressed by a dedicated 2D autoencoder, and a
Video Diffusion Transformer (VDiT) models their coupled distribution across time. We first train the model on a given time horizon to learn their coupled relationship and then fine-tune it autoregressively so it can extrapolate beyond the observed time window. Evaluated on an open-source CO2 sequestration
dataset, LAViG-FLOW generates saturation and pressure fields that stay consistent across time while running two orders of magnitude faster than traditional numerical solvers.
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Physics and Society · Cross-listed from cs.DL
Scientific production in the era of Large Language Models
Keigo Kusumegi, Xinyu Yang, Paul Ginsparg et al. (+3 more)
Large
Language Models (LLMs) are rapidly reshaping scientific research. We analyze these changes in multiple, large-scale
datasets with 2.1M preprints, 28K peer review reports, and 246M online accesses to scientific documents. We find: 1) scientists adopting LLMs to draft manuscripts demonstrate a large increase in paper production, ranging from 23.7-89.3% depending on scientific field and author background, 2) LLM use has reversed the relationship between writing complexity and paper quality, leading to an influx of manuscripts that are linguistically complex but substantively underwhelming, and 3) LLM adopters access and cite more diverse prior work, including books and younger, less-cited documents. These findings highlight a stunning shift in scientific production that will likely require a change in how journals, funding agencies, and tenure committees evaluate scientific works.
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All authors Keigo Kusumegi, Xinyu Yang, Paul Ginsparg, Mathijs de Vaan, Toby Stuart, Yian Yin
Optics
Measured group birefringence and group velocity dispersion of elliptical-core ZBLAN fibres for mid-infrared supercontinuum generation
Shreesha Rao D. S., Christian R. Petersen, Anupamaa Rampur et al. (+2 more)
Polarisation-maintaining ZBLAN optical fibres with small elliptical cores are attractive for nonlinear frequency conversion, for example in supercontinuum generation (SCG), and for dispersion management in ultrafast fibre
laser systems operating in the mid-infrared (MIR) spectral region. Accurate characterisation of group birefringence and group velocity dispersion (GVD) is essential for modelling ultrafast pulse propagation in such fibres, yet experimental data remain scarce. Here, we present broadband measurements of group birefringence and GVD in four elliptical-core ZBLAN fibres, selected for their potential for low-noise MIR SCG, over the wavelength range 1.4 to 4.3 {\mu}m. Using polarisation-resolved white-light spectral interferometry, we quantify the dispersion characteristics of both fundamental modes in each fibre. Measurement uncertainties are evaluated using a combined uncertainty analysis that includes the spread between repeated measurements and the uncertainty in the measured fibre length. This work aims to support the development of MIR supercontinuum sources and to facilitate the understanding of nonlinear optical phenomena in ZBLAN fibres.
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All authors Shreesha Rao D. S., Christian R. Petersen, Anupamaa Rampur, Ole Bang, Alexander M. Heidt
Instrumentation and Detectors
Depletion depth measurements of new large area silicon carbide detectors
A. Spatafora, D. Carbone, L. La Fauci et al. (+9 more)
The ion beam induced charge technique with
proton microprobe is used to characterise newly developed p-n junction large area silicon carbide detectors. They were recently produced as part of the ongoing program to develop a new particle identification wall for the focal plane detector of the MAGNEX
magnetic spectrometer at INFN - Laboratori Nazionali del Sud in view of the NUMEN experimental campaigns. Four silicon carbide devices are studied.
Proton beams over a 1.26 to 6.00 MeV incident energy range are used to probe the active area and the depletion depth of each device. The energy loss tables for the silicon carbide material are checked, finding an empirical correction that is then used to quantify the depletion depth at the full depletion voltage through energy loss measurements of 3.40 MeV
proton beams irradiating the back side of the devices. It is possible to fully deplete the devices provided that the epitaxial layer is grown properly on the substrate.
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All authors A. Spatafora, D. Carbone, L. La Fauci, G. A. Brischetto, D. Calvo, F. Cappuzzello, M. Cavallaro, A. Crnjac, K. Ivanković Nizić, M. Jakšić, D. Torresi, S. Tudisco
Plasma Physics
Electromagnetic ghosts in pair plasmas
Maxim Lyutikov
Collisions of two weakly nonlinear, $a_0 \ll 1$, counter-propagating EM pulses in pair
plasma leave behind a long-surviving collection of localized waves, an electromagnetic ghost. Waves are trapped (localized) by the random large density fluctuations created by the beat between the pulses. The process is similar to random
plasma density grating and/or Anderson-like wave localization. Structures survive for long, mesoscale times, while the EM energy slowly bleeds through high density walls of the density trap. Large guide
magnetic field, $\omega_B \geq $ few $\omega$, suppresses the formation of the ghosts.
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Computational Physics · Cross-listed from cond-mat.mtrl-sci
Disentangling the Discrepancy Between Theoretical and Experimental Curie Temperatures in Ferroelectric PbTiO$_3$
Denan Li, Christian S. Ahart and Shi Liu
Accurately predicting the Curie temperature ($T_c$) of ferroelectrics from first principles remains a major challenge, as theoretical estimates often fall significantly below experimental values. In this work, we investigate the origin of these discrepancies in the prototypical ferroelectric PbTiO$_3$ by performing extensive constant-pressure ab initio molecular dynamics (AIMD) simulations and benchmarking them against classical molecular dynamics (MD) using machine learning force fields (MLFFs) derived from first-principles data. Our results show that the underestimation of $T_c$ primarily stems from the limitations of the exchange-correlation functional, rather than inaccuracies in the MLFF fitting. We uncover a critical interplay between finite-size effects and the range of interatomic interactions: although short-range MLFFs appear to yield better agreement with experimental $T_c$, this improvement results from a fortuitous cancellation of errors. Incorporating explicit long-range interactions improves accuracy for larger supercells but ultimately leads to lower predicted $T_c$ values. These findings highlight that accurate finite-temperature predictions require not only high-quality training data and sufficiently large simulation
cells, but also the explicit treatment of long-range interactions and improved exchange-correlation functionals.
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Accelerator Physics
Aspects of Mechanical Engineering for Undulators
Haimo Joehri
This paper gives an overview about aspects of mechanical engineering of undulators. It is based mainly on two types that are used in the SwissFEL facility. The U15 Undulator is an example of an in-
vacuum type and the UE38 is an APPLE-X type. It describes the frame, the adjustment of the magnets with flexible keepers and the adjustment of the whole device with eccentric movers.
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Accelerator Physics
Innovations in High- and Ultra-precision Machining
Eckart Uhlmann, Mitchel Polte, Toni Hocke et al. (+1 more)
Modern precision manufacturing faces the challenge of integrating accuracy requirements into a framework of agile and sustainable production technologies. This development leads to numerous further challenges, affecting almost all areas of precision manufacturing industry. To overcome those challenges, this article presents promising technologies and innovative solution concepts from the field of temperature measurement in the cutting zone, process design for advanced materials, the development of reconfigurable machine tools, the optimization of the temperature behaviour of high-speed spindles and the use of edge computing in machine tools. Using the presented solutions, modern precision machining can be made more future-oriented in terms of sustainability and resilience.
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All authors Eckart Uhlmann, Mitchel Polte, Toni Hocke, Julius Tschöpel
History and Philosophy of Physics · Cross-listed from quant-ph
Noncontextual versus contextual interferometry
Jonte R. Hance, Jakov Krnic and Jan-Åke Larsson
Feynman famously said that single-particle interference is “a phenomenon which is impossible to explain in any classical way, and which has in it the heart of
quantum mechanics.” In this paper we show that some of the phenomenology of interference can be reproduced in a “classical” way, by reproducing the Elitzur-Vaidman Bomb Tester (including their improved version) using an extension of the
quantum simulation logic (QSL) formalism. Our result improves and simplifies a previous result by Catani et al, which relies on a much more complicated extension involving a “toy field theory.” We also show that not all single-particle interference can be explained by such a simple extension (including that of Catani et al), by showing that Hofmann's three-path interferometer is “nonclassical” in a very specific sense: it violates a Kochen-Specker-noncontextual inequality. Given that both our extension of QSL and Catani et al's extension are noncontextual – so do not reproduce the contextual behaviour of Hofmann's three-path interferometer – the behaviour of that interferometer is a proper example of a phenomenon that has in it the heart of
quantum mechanics, according to Feynman.
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Chemical Physics · Cross-listed from quant-ph
Comparison between explicit and implicit discretization strategies for a dissipative thermal environment
Xinxian Chen and Ignacio Franco
We investigate strategies for simulating open
quantum systems coupled to dissipative baths by comparing explicit wave function-based discretization [via multi-layer multi-configuration time-dependent Hartree (ML-MCTDH)] and the implicit density
matrix-based master equation method [via tree tensor network hierarchical equations of motion (TTN-HEOM)]. For dissipative baths characterized by exponentially decaying bath correlation functions, the implicit discretization approach of HEOM – rooted in bath correlation function decompositions – proves significantly more efficient than explicit discretization of the bath into discrete harmonic modes. Explicit methods, like ML-MCTDH, require extensive mode discretization to approximate continuum baths, leading to computational bottlenecks. Case studies for two-level systems and a Fenna–Matthews–Olson complex model highlight TTN-HEOM's superiority in capturing dissipative dynamics with relaxations with a minimal number of auxiliary modes, while the explicit methods are as exact as the HEOM in pure dephasing regimes. This comparison is enabled by the TENSO package, which has both ML-MCTDH and TTN-HEOM implemented using the same computational structure and propagation strategy.
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Optics · Cross-listed from cond-mat.dis-nn
Polychronous Wave Computing: Timing-Native Address Selection in Spiking Networks
Natalila G. Berloff
Spike timing offers a combinatorial address space, suggesting that timing-based spiking inference can be executed as lookup and routing rather than as dense multiply–accumulate. Yet most neuromorphic and photonic systems still digitize events into timestamps, bins, or rates and then perform selection in clocked logic. We introduce Polychronous Wave Computing (PWC), a timing-native address-selection primitive that maps relative spike latencies directly to a discrete output route in the wave domain. Spike times are phase-encoded in a rotating frame and processed by a programmable multiport interferometer that evaluates K template correlations in parallel; a driven–dissipative winner-take-all stage then performs a physical argmax, emitting a one-hot output port. We derive the operating envelope imposed by phase wrapping and mutual coherence, and collapse timing jitter, static phase mismatch, and dephasing into a single effective phase-noise budget whose induced winner–runner-up margin predicts boundary-first failures and provides an intensity-only calibration target. Simulations show that nonlinear competition improves routing fidelity compared with noisy linear intensity readout, and that hardware-in-the-loop phase tuning rescues a temporal-order gate from 55.9% to 97.2% accuracy under strong static mismatch. PWC provides a fast routing coprocessor for LUT-style spiking networks and sparse top-1 gates (e.g., mixture-of-experts routing) across polaritonic, photonic, and oscillator platforms.
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Optics · Cross-listed from eess.IV
Non-Invasive Diagnosis for Clubroot Using Terahertz Time-Domain Spectroscopy and Physics-Constrained Neural Networks
Pengfei Zhu, Jiaxu Wu, Alyson Deslongchamps et al. (+2 more)
Clubroot, a major soilborne disease affecting canola and other cruciferous crops, is characterized by the development of large galls on the roots of susceptible hosts. In this study, we present the first application of terahertz time-domain spectroscopy (THz-TDS) as a non-invasive diagnosis tool in plant pathology. Compared with conventional molecular, spectroscopic, and immunoassay-based methods, THz-TDS offers distinct advantages, including non-contact, non-destructive, and preparation-free measurement, enabling rapid in situ screening of plant and soil samples. Our results demonstrate that THz-TDS can differentiate between healthy and clubroot-infected tissues by detecting both structural and biochemical alterations. Specifically, infected roots exhibit a blue shift in the refractive index in the low-frequency THz range, along with distinct peaks-indicative of disruptions in water transport and altered metabolic activity in both roots and leaves. Interestingly, the characteristic root swelling observed in infected plants reflects internal tissue disorganization rather than an actual increase in water content. Furthermore, a physics-constrained neural network is proposed to extract the main feature in THz-TDS. A comprehensive evaluation, including time-domain signals, amplitude and phase images, refractive index and absorption coefficient maps, and principal component analysis, provides enhanced contrast and spatial resolution compared to raw time-domain or frequency signals. These findings suggest that THz-TDS holds significant potential for early, non-destructive detection of plant diseases and may serve as a valuable tool to limit their spread in agricultural systems.
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All authors Pengfei Zhu, Jiaxu Wu, Alyson Deslongchamps, Yubin Zhang, Xavier Maldague
Plasma Physics
Oxygen atom density and kinetics in intermediate-pressure radiofrequency capacitively-coupled plasmas in pure O2
Shu Zhang, Andrey Volynets, Garrett A. Curley et al. (+1 more)
We have studied radiofrequency capacitively coupled
plasmas in pure O2 using single mode
laser cavity ringdown spectroscopy of oxygen atoms at 630 nm. The absolute atom densities and translational temperatures were determined over a range of pressures and RF power . At pressures of 267 Pa and above, the O atom mole fraction increases with RF power and decreases with pressure, reaching a maximum of 15 percent. However, at 133 and 67 Pa it passes through a distinct maximum with power before decreasing significantly. The atom recombination processes are probed by time resolved measurements in the afterglow of pulse modulated
plasmas. At 133 and 67 Pa the atom loss is dominated by surface recombination, and we see clear evidence that this rate is increased by energetic ion bombardment, in agreement with a study from Bill Graham group. This effect partially explains the observed decrease in dissociation at high RF power. The time-resolved results also allow the O negative ion density to be determined and indicate the creation of ozone in the afterglow. At 133 Pa, the trends with RF power of the O2 dissociation, O negative ion density and gas temperature suggest a transition at high power to a
plasma mode with fewer high energy electrons. At higher pressures gas phase recombination mechanisms become dominant, however gas convection driven by gas cooling in the afterglow makes it complex to analyse the time-resolved data.
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All authors Shu Zhang, Andrey Volynets, Garrett A. Curley, Jean-Paul Booth
Applied Physics
Sel-assembled Rhodium Nanoantennas for Single-Protein UV SERS
Yanqiu Zou, Nicco Corduri, Francesco DAmico et al. (+11 more)
Surface-enhanced Raman scattering (SERS) provides critical insights into analyte structure, dynamic processes, and intermolecular interactions at the single-molecule level. By exploiting the hotspot formation in the vicinity of plasmonic structures, SERS constitutes an established tool for fundamental biological research, particularly for early-stage disease diagnostics. In this context, the DNA Origami technique, with its high addressability, enables both the assembly of plasmonic nanostructures with nanometric accuracy, and the deterministic placement of a single analyte molecule precisely at the generated hotspot within them. To date, most DNA Origami based nanoantennas rely on gold or silver nanoparticles (NPs), whose plasmonic resonances are confined to the visible spectrum, severely limiting their use in other spectral ranges. To extend the operating range, we have recently established a robust strategy for self-assembling programmable ultraviolet (UV)-plasmonic dimer
antennas using rhodium nanocubes. Herein, we leverage this tailored architecture to systematically investigate its performance for single-molecule UV-SERS. We demonstrated how biofabricated Rh-dimers can be used to detect the characteristic SERS signal of a single streptavidin molecule linked at the dimer s gap. Our results are validated through polarization dependent measurements that yield the expected signal modulation depending on the the dimer orientation only for the DNA origami with a
protein at the hotspot. This work establishes a highly sensitive and polarization-tunable UV-SERS platform, laying a solid foundation for label-free optical investigation and bio-spectroscopy of individual biomolecules in the UV spectral range.
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All authors Yanqiu Zou, Nicco Corduri, Francesco DAmico, Karol Kolataj, Huaizhou Jin, Zhenrong Zheng, Yifan Yu, Jie Liu, Shukun Weng, Ali Douaki, Jerome Wenger, Shangzhong Jin, Guillermo Acuna, Denis Garoli
Optics
Dislocation Entropy: Temperature and Density Dependence
A. G. Sukharev
Laser hardening of metals occurs under the influence of a shock wave, which changes the distribution and density of one-dimensional defects - dislocations. There is a relationship between the density of dislocations, the grain size and the resistance of a single
crystal to shear loading. The mechanism of hardening processes continues to be intensively studied, and the dynamics of defects plays a central role here. In this paper, the dislocation
entropy is analyzed from a combinatorial point of view and from the point of view of a physical oscillator with a given energy reserve. Both contributions play an important role in describing the free energy of a one-dimensional ensemble of dislocations, and are necessary to take into account the dynamic processes inside the grain of a polycrystalline structure. Keywords:
Laser Shock Peening, statistical mechanics
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Applied Physics · Cross-listed from cond-mat.soft
Multiscale Prediction of Polymer Relaxation Dynamics via Computational and Data-Driven Methods
Nguyen T. T. Duyen, Ngo T. Que and Anh D. Phan
We present a multiscale modeling approach that integrates molecular dynamics simulations, machine learning, and the Elastically Collective Nonlinear Langevin Equation (ECNLE) theory to investigate the glass transition dynamics of
polymer systems. The glass transition temperatures (Tg) of four representative
polymers are estimated using simulations and machine learning model trained on experimental
datasets. These predicted Tg values are used as inputs to the ECNLE theory to compute the temperature dependence of structural relaxation times and
diffusion coefficients, and the dynamic fragility. The Tg values predicted from simulations show good quantitative agreement with experimental data. While machine learning tends to slightly overestimate Tg, the resulting dynamic fragility values remain close to experimental fragilities. Overall, ECNLE calculations using these inputs agree well with broadband dielectric spectroscopy results. Our integrated approach provides a practical and scalable tool for predicting the dynamic behavior of
polymers, particularly in systems where experimental data are limited.
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Data Analysis and Statistics · Cross-listed from eess.IV
PYVALE: A Fast, Scalable, Open-Source 2D Digital Image Correlation (DIC) Engine Capable of Handling Gigapixel Images
Joel Hirst, Lorna Sibson, Adel Tayeb et al. (+10 more)
Background: Digital Image Correlation (DIC) is a widely used full-field measurement technique, but both open-source and commercial packages often have limitations such as operating-system restrictions, lack of support for deployment on computing clusters, and poor scalability to gigapixel-scale images common in Scanning Electron Microscopy DIC (SEM-DIC). Objective: Pyvale is an open-source software package designed for sensor simulation, uncertainty quantification, placement optimization, and calibration/validation. A key component of this is the development of a dedicated 2D DIC module intended for standalone use and integration within broader workflows. Methods: Pyvale provides a user-friendly Python interface with performant compiled routines underneath. At its core is a multithreaded, reliability-guided DIC
algorithm. Its open-source MIT license enables wide deployment, including on computing clusters and in automated pipelines. Results: Benchmarking with the publicly available 2D DIC challenge 2.0
dataset shows that Pyvale achieves metrological performance comparable to existing commercial and open-source DIC codes. It can correlate gigapixel-scale image pairs in under 5 minutes on high-specification desktop workstations, with
memory peaking at approximately 50 GB. Conclusions: Pyvale's strong metrological foundation, coupled with its scalability for SEM-DIC, positions it as a platform for sustained, community-driven development. Its design and licensing provide a foundation for future improvements in open-source DIC and integration into experimental design and validation workflows.
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All authors Joel Hirst, Lorna Sibson, Adel Tayeb, Ben Poole, Megan Sampson, Wiera Bielajewa, Michael Atkinson, Alex Marsh, Rory Spencer, Rob Hamill, Cory Hamelin, Allan Harte, Lloyd Fletcher
Biological Physics · Cross-listed from cond-mat.stat-mech
Direct measurement of the Orderphobic Effect
O.D. Lunn, J.G. Downs, K.K. Mandadapu et al. (+2 more)
Fluctuation-induced forces, such as the Critical Casimir Effect (CCE), are fundamental mechanisms driving organization and self-assembly near second-order phase transitions. The existence of a comparable, universal force for systems undergoing a first-order transition has remained an unresolved fundamental question. The proposed Orderphobic Effect is one such potential mechanism. It arises from minimisation of the interfacial free energy between solutes that locally nucleate a disordered phase. Here, we report the first experimental demonstration and quantitative measurement of the Orderphobic Effect. Using a driven, non-
equilibrium quasi-2D granular fluid undergoing a first-order order-disorder transition, we show that specifically designed solutes in an ordered phase nucleate a coexisting “bubble” of the disordered phase. By analysing its capillary fluctuations, we confirm that this phenomenon occurs due to the proximity to phase-coexistence, and we directly quantify the attractive force by measuring the interaction free energy between solutes. The observation of this general fluctuation-mediated force in a non-
equilibrium steady state strongly supports its claimed universality. Our work establishes the Orderphobic Effect as the first-order equivalent to the CCE, providing a new, general route for controlling self-assembly and aggregation in soft matter and non-
equilibrium systems.
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All authors O.D. Lunn, J.G. Downs, K.K. Mandadapu, J.P. Garrahan, M.I. Smith
Fluid Dynamics
Flapping strategies for flying formations
Javier Chico-Vázquez and Christiana Mavroyiakoumou
Long arrays of identical, self-propelling flapping flyers are inherently unstable and thus unlikely to exist without active control mechanisms. One approach to enable long in-line formations is to enforce a constant separation between the group members. The objective then becomes to determine the flapping strategies the flyers should adopt to achieve a certain separation. Using an aerodynamic model of
vortex wake production and inter-flyer effects, we explore different flapping strategies for followers given the motion of the leader. The choice of tactic is dependent upon the aerodynamic, kinematic, and physical parameters of the system, and reflects an interplay between efficiency and stability. We find that whether a flyer flaps in or out of phase with its upstream neighbour, together with the target separation, strongly affect the flapping amplitude and, therefore, the energetic cost of group flight. In certain regimes, group flight is energetically favourable compared to isolated flight, while in others, flying in formation becomes less efficient. We also identify "goldilocks zones", ranges of separation in which one of the in- or out-of-phase motions can be simultaneously energetically efficient and dynamically stable. Outside these regions, energetically favourable flight is unstable and therefore unlikely to occur.
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