Physics and Society
The dynamics of early transoceanic voyages: A resource-coupled model of crew health and survival
Nuno Crokidakis
The great transoceanic voyages of the Age of Discovery imposed severe human costs on their crews. Long travel durations, deteriorating sanitary conditions, and finite food and water supplies made disease, exhaustion, and mortality central features of maritime expansion. We propose a minimal compartmental model describing the voyage itself as a dynamical system coupling crew health and resource depletion. The population is divided into healthy, ill, and dead individuals, while an additional variable represents the effective level of provisions on board. Illness incidence depends nonlinearly on resource availability, capturing the increasing health risk associated with deteriorating food, water, and sanitary conditions. The coupled ordinary differential equations are analyzed in the transient regime relevant to finite-duration voyages. Rather than reconstructing specific historical expeditions, the model identifies generic mechanisms linking provisioning, health deterioration, mortality, and voyage duration. Numerical results show that resource limitations can substantially reduce the healthy and operational fraction of the crew even when overall survival remains relatively high, revealing a distinction between demographic survival and operational viability. Increasing initial provisioning delays the crossover at which ill individuals become as numerous as healthy individuals and extends the period over which the crew remains predominantly operational. We also introduce a critical provisioning time, defined as the time required for resources to reach a prescribed stress threshold, and find an approximately linear dependence on the initial resource buffer. The framework provides a quantitative perspective on the internal dynamics of early transoceanic navigation and illustrates how dynamical-systems approaches can contribute to the study of historical processes.
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Biological Physics · Cross-listed from cond-mat.stat-mech
Universal 1/f Noise in the Power Spectra of Energy Time-series in Solvated DNA Dynamics
Harsh Sahu, Deepika Sardana, Pramod Kumar et al. (+3 more)
We investigate energy fluctuations of solvated DNA in three conformations: G-quadruplex, Hairpin, and Duplex. Our comprehensive molecular dynamics (MD) simulations demonstrate that the time-series of interaction energies for DNA self, DNA-water and DNA-ion show 1/f noise with a universal decay exponent $\beta \simeq 0.90$. We show that DNA
topology and structural rigidity modulate its dynamic coupling with the surrounding hydration shell and mobile counter-ions. This coupling critically shapes the 1/f noise profile: DNA self energies in flexible structures (G-quadruplex, Hairpin) display pronounced low-frequency modes absent in the rigid Duplex. These findings reveal how the interplay between DNA
topology and environmental coupling governs different
stochastic behavior in biologically relevant forms of DNA.
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All authors Harsh Sahu, Deepika Sardana, Pramod Kumar, Ajay Kumar Chand, Sobhan Sen, Sanjay Puri
Chemical Physics
FOSY: Segmental Backbone Assignment in Intrinsically Disordered Proteins
Dmitry M. Lesovoy, Tatiana Agback, Panagiota S. Georgoulia et al. (+3 more)
Backbone resonance assignment is a prerequisite for most biomolecular NMR applications, yet conventional multidimensional strategies frequently fail for intrinsically disordered
proteins (IDPs) and regions (IDRs) because of severe spectral overlap, rapid amide
proton exchange with water, and missing sequential correlations. In many biological applications, however, complete
protein assignment is unnecessary, as only a limited sequence segment surrounding a functional site is required. Here we introduce segmental backbone assignment, an assignment strategy implemented by FOcused SpectroscopY (FOSY), which concentrates experimental effort on relatively short regions while retaining the high-dimensional sequential connectivity needed for unambiguous assignments. We present a self-consistent suite of selective two-dimensional FOSY experiments that enables bidirectional assignment walks along the
protein sequence through complementary forward and backward transfer schemes. The methodology employs frequency-selective polarisation transfer to replace high-dimensional experiments with sensitive and readily interpretable 2D spectra while preserving the information content of multidimensional correlation experiments. The approach is demonstrated by completing the assignment of G302-K311 segment, which is missing in the published assignment of the 441-residue human Tau
protein. The approach complements conventional multidimensional or residue type-selective assignment strategies by providing an efficient means of traversing assignment interruptions and rapidly characterising functionally important segments in intrinsically disordered
proteins.
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All authors Dmitry M. Lesovoy, Tatiana Agback, Panagiota S. Georgoulia, Irena Matecko-Burmann, Bjorn M. Burmann, Vladislav Y. Orekhov
Atomic Physics
Small-Angle Differential Cross Sections for Symmetrical Resonant Charge Exchange in Molecular Hydrogen
Jibak Mukherjee, Kamal Kumar, Harpreet Singh et al. (+2 more)
We measured state selective scattering angle distributions in non-dissociative-state single electron capture in $\lbrace 5, 7.5, 10\rbrace$ keV/u, $\left[\mathrm{H^+ + H_2}\right]$ and $\left[\mathrm{H_2^+ + H_2}\right]$ collisions, using Cold Target Recoil Ion Momentum Spectroscopy (COLTRIMS). In our measurements, range of the scattering angle was small where diffraction effect is expected to take place, and, the ground state electron capture - symmetrical resonant channel for the $\mathrm{H_2^+}$ projectile and near resonant channel for the $\mathrm{H^+}$ projectile - was fully resolved from other channels. We analyzed the data considering $\mathrm{H_2^+}$ and $\mathrm{H_2}$ possess two independent-identical scattering centers and exhibit multi center interference effect. By comparing these equal-velocity collisions, we investigated the atomic nature of the individual scattering centers. We observed Fraunhofer diffraction from a circular aperture like patterns with equal fringe widths, for both the projectiles, in ground state channel. We applied a simple toy model to reconstruct the circular apertures.
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All authors Jibak Mukherjee, Kamal Kumar, Harpreet Singh, Manojit Das, Deepankar Misra
Applied Physics
Three-dimensional vector waves in time-variant materials, with applications in time-reversed focusing and Green's function retrieval
Kees Wapenaar and Dirk-Jan van Manen
The behavior of wave propagation and scattering in time-variant materials has been studied by many authors, for electromagnetic as well as for mechanical waves. Most studies consider two-dimensional waves, governed by scalar wave equations. Here we introduce a unified wave equation for three-dimensional electromagnetic and elastodynamic vector-wave propagation and scattering in homogeneous, time-variant materials. Using the
symmetry properties of this equation, we establish the conservation of net field-momentum density, and a reciprocity relation between causal and acausal Green's functions. The latter relation is exploited in the derivation of the counterparts of classical time-reversed focusing and Green's function
retrieval for time-variant materials.
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Atmospheric and Oceanic Physics
Unreported large errors from two PAMGuard three-dimensional localizers of whale calls
Maya Mathur, Luke Stoner-Eby, Devin Pascoe et al. (+1 more)
Confidence intervals of location (CIL) of calling marine mammals, derived from time-differences-of-arrival (TDOA) between receivers, depend on errors of TDOAs, receiver location, clocks, sound speeds, and location method. When these errors are minuscule, simulations yield small errors of PAMGuard's 3D simplex localizer when click sounds of beaked and sperm whales originate in a 1000 x 1000 x 1000 $\mbox{m}^3$ region using five receivers having horizontal and vertical separations of 1000 m and 150 m respectively. Realistic uncertainties of sound speed up to $\pm 10$ m/s lead to errors up to $10^{14}$ m. With clocks maintained by atomic standards and common practice of correcting TDOA from synchronization measurements at the start and end of an experiment, errors of location are up to $10^{4}$ m. Errors up to $10^2$ and $10^3$ m are found when the receiver's locations are uncertain within 10 and 40 m respectively. Errors of PAMGuard's 3D
hyperbolic localizer are almost independent of the above uncertainties, yielding errors of location up to about $10^4$ m even when simulated errors are minuscule. Causes of PAMGuard's 3D location errors are unknown. These
algorithms are briefly compared to another method designed to yield a reliable CIL.
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All authors Maya Mathur, Luke Stoner-Eby, Devin Pascoe, John L. Spiesberger
Plasma Physics
Experimental setup for testing nanocalorimeter sensors as a plasma diagnostics tool
Carles Corbella, Feng Yi and Andrei Kolmakov
The application of microfabricated nanocalorimeters for real-time, highly sensitive, and selective monitoring of the energy fluxes from low-pressure
plasma discharges has been reported recently. Here, we describe the experimental setup for complementary characterization of nanocalorimeters performance using
plasma diagnostics techniques. Langmuir probe, retarding field energy analyzer (RFEA), optical emission spectroscopy (OES), quadrupole mass spectrometry (QMS), and thermocouple-based thermometry constitute the
plasma monitor suite. We discuss two application examples of the
plasma monitor suite: (1) discrimination between electron- and ion-induced heat fluxes via sensor direct current (DC) biasing, and (2) detection of fast temperature transients in pulsed discharges. The main goal of this work is to demonstrate a nanocalorimetry platform as a real-time metrology for
plasma processing and process control.
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Applied Physics · Cross-listed from cond-mat.mtrl-sci
Divergent Solid-state Conversion Pathways in Evaporated All-perovskite Tandem Solar Cells
Huagui Lai, Amber Wright, Nick Huber et al. (+8 more)
Sequential thermal evaporation (sTE) is emerging as a solvent-free route to high-quality mid-bandgap perovskites, but its extension to mixed-halide wide-bandgap (WBG) and Sn-Pb narrow-bandgap (NBG) absorbers for all-perovskite tandem solar
cells (TSCs) remains limited by an incomplete understanding of solid-state conversion. Here, using time-sliced ex situ analysis, we reveal divergent solid-state conversion mechanisms in sequentially evaporated WBG and NBG precursor stacks. In WBG stacks, formamidinium (FA)-containing species penetrate the inorganic template and Br/I redistribution precedes substantial three-dimensional perovskite formation. The photoactive phase then crystallizes from a chemically mixed reservoir, and absolute PbBr$_2$ thickness, rather than nominal PbBr$_2$/PbI$_2$ ratio, determines the final bandgap. In NBG stacks, by contrast, an early Pb-rich perovskite phase forms upon formamidinium iodide deposition, restricting further FA penetration into the buried SnI$_2$ precursor. Subsequent annealing promotes rapid
lattice reorganization faster than Sn/Pb interdiffusion, leaving vertical compositional gradients. Guided by these insights, we develop sTE absorbers with bandgaps spanning 1.26-1.96 eV and demonstrate the first evaporated all-perovskite TSC, reaching a power conversion efficiency of 19.2%. Encapsulated tandems retain on average 80% of their initial efficiency after 1,200 h at 65 $^\circ$C (ISOS-D-2). These results establish bandgap-specific control of solid-state conversion as a design principle for sequentially evaporated perovskite tandem photovoltaics.
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All authors Huagui Lai, Amber Wright, Nick Huber, Niels Uythoven, Federico De Giorgi, Jincheng Luo, Tristan Sachsenweger, Sunil B. Shivarudraiah, Chih-Jen Shih, Wolfgang Tress, Fan Fu
Applied Physics
Energy Harvesting for Self-Powered Microsystems: A Critical Review of Materials, Power Management, and System Integration
Lyuye Lin, Feng Zhifu, Ermanno Miele et al. (+12 more)
The relentless proliferation of the Internet of Things (IoT), wearable bioelectronics, and cyber-physical infrastructure has rendered the conventional electrochemical battery the single most prohibitive bottleneck to long-term, maintenance-free autonomous microsystems. Energy harvesting, i.e. the conversion of ambient mechanical, thermal, and radiative energy into usable electrical power, has consequently emerged as a transformative paradigm to realize perpetual, battery-independent operation. This review critically synthesizes the most significant advances in energy harvesting technologies over the recent period, with a focus on triboelectric nanogenerators (TENGs), piezoelectric and pyroelectric transducers, indoor photovoltaics,
radio-frequency (RF) rectennas, and their multi-source hybrid integrations. We highlight paradigm-shifting breakthroughs, including
liquid-solid TENGs that eliminate mechanical wear, nonlinear piezoelectric oscillators that broaden operational bandwidth by over 300%, machine-learning-accelerated material discovery for high charge-density dielectrics, and multiband and broadband RF harvesting enabled by metamaterial architectures. Crucially, we move beyond conventional materials-centric narratives to critically interrogate the "unseen" system-level bottlenecks: ultra-low-voltage cold-start power management integrated
circuits (PMICs), the impedance-matching challenges of hybrid energy sources, and the persistent degradation of micro-supercapacitors and thin-film batteries under realistic field conditions.
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All authors Lyuye Lin, Feng Zhifu, Ermanno Miele, Giuseppe Cantarella, Elena Degoli, Diego Angeli, Lethy Krishnan Jagadamma, Feng Gao, Michele Magno, Ivano Eligio Castelli, Tommaso Ongarello, Chunbo Liu, Roman Krahne, Denis Garoli, Remo Proietti Zaccaria
Geophysics · Cross-listed from astro-ph.EP
Thermal Evolution of Lava Planets Across System Ages: Predictions for Hell of a Survey
Mariana Sastre, Tim Lichtenberg, Lisa Dang et al. (+22 more)
Ultra-short-period (USP) rocky
exoplanets can have dayside temperatures high enough to maintain permanent magma oceans, sitting at the intersection of interior geophysics and atmospheric chemistry. Coupled feedbacks between the molten surface and outgassed atmosphere can sustain or enhance a volatile envelope, while stellar interactions can erode it. Understanding which outcome prevails, and its observable imprint, requires a multi-target approach across
planets at different stages of thermal
evolution. We present predictions for the five targets of JWST Cycle 4 program 8864: TOI-1807 b, TOI-2260 b, TOI-431 b, TOI-6255 b, and TOI-2431 b. Using the PROTEUS coupled interior-atmosphere framework, we construct a simulation grid and classify outcomes into six categories, defined by the final interior melt state and by whether the
planet retains a detectable atmosphere thick enough to redistribute heat to the nightside. For targets retaining a non-negligible volatile envelope, our models predict higher partial pressures for most species when the surface is molten, except for S$_{2}$, whose enhancement in the solid regime suggests it may serve as a tracer of interior melt state. Despite some targets showing outcomes across multiple scenarios, most tend toward a bare-rock end-member, with global melt fraction $\leq$ 20% and atmospheric retention sensitive to escape efficiency. Our analysis reveals a minimum escape efficiency threshold below which volatile envelopes survive under energy-limited escape, constraining the conditions required for atmosphere survival on irradiated rocky
planets. These predictions will guide interpretation of MIRI-LRS phase curve observations and identify which targets and features best discriminate between competing geophysical states.
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All authors Mariana Sastre, Tim Lichtenberg, Lisa Dang, Anjali Piette, Haiyang S. Wang, Mercedes López-Morales, Thomas Wilson, Charles-Édouard Boukaré, Mahesh Herath, Nicolas Cowan, Md Abdullah Al Zaman, Madyson G. Barber, Casey Brinkman-Traverse, Nicholas Connors, Ian Crossfield, Lina D'Aoust, Oliver Herbort, Leoni Janssen, Mathilde Kervazo, Owen Lammert, Yamila Miguel, Raymond Pierrehumbert, Allona Vazan, Joost P. Wardenier, Sebastian Zieba
Optics
Characterization of spatially inhomogeneous chirp in ultrashort multielectron beams via femtosecond hole burning
Yuichi Tachibana and Yuya Morimoto
Direct observation of the temporal-energy structure of pulsed electron beams is crucial for beam-driven light generation and time-resolved microscopic imaging. In this study, we characterized the spatially non-uniform time-energy structure in multi-electron ultrashort pulses exhibiting significant space-charge effects. By combining spectral hole burning originating from the
photon-induced near-field electron microscopy (PINEM) effect with angle-resolved energy analysis, we observed time-energy correlations at each beam angle. Applying this method to 37-keV pulses containing up to 17 electrons per pulse, we determined energy spread and chirp rate, which vary by up to 100% and 40%, respectively, across the entire beam. These findings highlight the importance of characterizing multi-electron pulses with spatial or angular resolution and suggest the utility of spatially modulated light for the shaping of high-flux pulsed electron beams.
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Accelerator Physics
Reconstruction of Beam Transverse Parameters in the Fermilab Side-Coupled Linac Using a Normalized Coordinate Framework
E. V. Chen, J-P. Carneiro, R. V. Sharankova et al. (+1 more)
Quadrupole scans are a commonly used tool for beam second moment reconstruction. Limitations in the strength of the magnets and layout of the beamline elements frequently preclude simple quadrupole-drift-detector scans from collecting sufficient data for reconstruction. Using a normalized coordinate framework, we characterize the prerequisites for a robust simple quadrupole scan and expand these prerequisites to reconstruction from more complex optics. The beam second moments are investigated at two locations in the Fermilab Side-Coupled Linac under simple and complex optics, using this framework to maximize information gained from wire scanner profile measurements.
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All authors E. V. Chen, J-P. Carneiro, R. V. Sharankova, A. V. Shemyakin
Instrumentation and Detectors · Cross-listed from hep-ex
A heterogeneous and vectorized sequence for the HL-LHC full tracking reconstruction of the CMS experiment
Emmanouil Vourliotis
This contribution presents the new baseline strategy for the Phase-2 tracking of the CMS experiment for online event reconstruction, and for the main iteration of offline tracking. This tracking sequence takes advantage of the combination of cutting-edge tracking
algorithms that are either optimized for parallel execution on GPUs (Patatrack and LST), or vectorized for efficient CPU performance (mkFit). Such a combined approach offers an effective solution to deal with the unprecedented computational challenges caused by the large number of simultaneous collisions per bunch crossing expected at the High-Luminosity Large
Hadron Collider (HL-LHC). The proposed combination not only reduces the computational resource requirements but also enhances the physics reach by incorporating displaced tracking and increasingly leveraging machine learning techniques.
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Optics
Frequency Attraction and Repulsion in Lasers with Complex Mutual Coupling
Amit Pando, Tomer Hacohen, Eran Bernstein et al. (+3 more)
We experimentally investigate
laser synchronization under complex mutual coupling, featuring both dissipative and dispersive components. Using a reconfigurable digital degenerate cavity
laser with precise control over system parameters, we show that complex coupling can induce both frequency attraction and repulsion, in contrast to common models of coupled oscillators. Furthermore, we show that these frequency shifts can be exploited to significantly enhance global synchronization in multi-
laser arrays. Comparison with numerical and theoretical results indicate that amplitude dynamics of complex coupled
lasers play an important role in the observed phenomena. Our results establish a versatile platform for exploring non-Hermitian physics and topological states in tailored
laser networks.
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All authors Amit Pando, Tomer Hacohen, Eran Bernstein, Victor Shelukin, Asher Friesem, Nir Davidson
Instrumentation and Detectors
Commissioning and Performance of the Time-of-Flight Detector for the T2K Neutrino Oscillation Experiment
C. Alt, L. Amziane, N. Baudis et al. (+23 more)
The T2K ND280 Upgrade aims to reduce systematic uncertainties in measurements of
neutrino oscillation parameters and improve sensitivity to the charge-parity (CP)-violating phase, $\delta_{\mathrm{CP}}$. A key component is the Time-of-Flight (ToF) detector, comprising six panels with 118 EJ-200 plastic-scintillator bars surrounding the Super Fine-Grained Detector (SuperFGD) and two High-Angle Time Projection Chambers (HA-TPCs). Each bar is read out at both ends by silicon photomultiplier arrays and digitised using SAMPIC waveform electronics. The ToF provides precise timing and particle-direction information for particle identification and rejection of backgrounds entering the tracker from outside. This article presents the detector design, construction, signal reconstruction, integration, commissioning, and performance. Dedicated single-bar measurements achieve a time resolution of approximately 130 ps and a longitudinal position resolution of 2.6 cm. After installation in ND280,
cosmic-ray calibration yields an in situ single-bar time resolution of $169 \pm 1$ ps for Top-Bottom crossing events. Beam data clearly resolve the eight-bunch T2K spill structure, confirming synchronisation with the ND280 trigger and data-acquisition systems. The ToF has been successfully commissioned and operates stably within the upgraded ND280 detector.
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All authors C. Alt, L. Amziane, N. Baudis, A. Blanchet, S. Bordoni, T. H. Bui, F. Cadoux, P. Collard, M. El Baz, Y. Favre, L. Giannessi, G. Ha, C. Jesús-Valls, V. S. Kasturi, A. Klustová, A. Korzenev, T. A. Le, T. Lux, A. D. Nguyen, D. T. Nguyen, H. Nguyen, S. Samani, F. Sánchez, M. Ta, T. Thaiduc, E. Villa
Optics
Transient High-Harmonic Generation from Solids: From Spectroscopy and Control to Programmable Emission
Pieter J. van Essen, Torben Ham, Zhonghui Nie et al. (+1 more)
High-harmonic generation (HHG) from solids has emerged as a powerful probe of electronic structure and ultrafast dynamics in condensed matter systems. In this chapter, we review recent advances in solid-state HHG spectroscopy and control, with a focus on
semiconductors and correlated materials. We discuss the theoretical foundations of HHG and summarize experimental approaches for extracting information from harmonic emission. HHG has been shown to be sensitive to a wide range of microscopic properties, including band structure, transition dipole moments, Berry phases,
crystal symmetry, carrier populations, dephasing processes, and
lattice dynamics. This sensitivity enables access to electronic and structural dynamics on femtosecond and attosecond timescales and has established HHG as a versatile spectroscopic tool. At the same time, the strong dependence of HHG on many coupled material and excitation parameters makes the emitted harmonics intrinsically difficult to associate with a single microscopic quantity. Rather than representing a limitation alone, this sensitivity also provides numerous pathways for control. We review how photoexcitation, multicolor driving fields, waveform engineering, and transient modification of material properties can be used to enhance, suppress, and shape harmonic emission. These developments position solid-state HHG not only as a spectroscopic technique, but also as a platform for programmable nonlinear optics with applications ranging from compact extreme-ultraviolet sources to super-resolution microscopy and ultrafast photonic devices.
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All authors Pieter J. van Essen, Torben Ham, Zhonghui Nie, Peter M. Kraus
Physics and Society
When higher-order interactions matter: reducibility, parsimony, and microscopic organization
Alex Arenas, Federico Battiston and Andrea Gabrielli
The current debate on higher-order interactions raises a fundamental question: when can systems organized through group interactions be faithfully represented within a graph-based formalism? Recent results show that graph descriptions can reproduce higher-order dynamics exactly or preserve selected macroscopic observables. Yet reducibility does not necessarily imply simplification, as information removed from the interaction structure may reappear as complexity in the effective dynamics, while structural features such as nestedness, heterogeneity, and cross-order correlations may be obscured by the reduction. We argue that formal representability alone is insufficient as a criterion for model choice. Both "simpler" and "equivalent" are question-dependent notions: parsimony must be assessed for the complete structure-dynamics model, and adequacy must be defined relative to the observables, scales, and regimes required by the scientific question. A reduced model may therefore be fully adequate for locating a phase transition or identifying a universality class while being inadequate for reproducing microscopic trajectories, transient dynamics, or structure-function relations. When group structure carries relevant microscopic information, higher-order representations may remain the most direct, interpretable, and parsimonious description, as well as the natural framework for understanding how microscopic organization gives rise to macroscopic behavior and functionality.
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Applied Physics · Cross-listed from cond-mat.mtrl-sci
Anharmonic Phonon Renormalization and Defect Tolerance of the Thermoelectric Power Factor in Monolayer SnSe
Nguyen Tran Gia Bao, Thang Bach Phan, Vu Thi Hanh Thu et al. (+1 more)
Monolayer tin selenide (SnSe) exhibits phase-dependent anharmonic
lattice dynamics, yet their consequences for the thermoelectric power factor (PF) and point-defect tolerance remain unresolved. We combine density functional theory, the
stochastic self-consistent harmonic approximation (SSCHA), and Boltzmann transport calculations including electron-
phonon and electron-defect scattering to investigate monolayer $\alpha$-SnSe (Pnma) and $\beta$-SnSe (Cmcm). In dynamically stable $\alpha$-SnSe, SSCHA renormalizes the finite-temperature
phonons without changing the qualitative n-type transport picture. In $\beta$-SnSe, SSCHA removes the harmonic soft-mode instability of the Cmcm phase at 800-1000 K, and thereby enables high-temperature transport calculations; LO/TO-2 is the principal electron-scattering channel. In the lower-density window near $10^{12}$ cm$^{-2}$, the n-type PF reaches 15-19 $\mu\mathrm{W}/(\mathrm{K}^{2}\cdot\mathrm{cm})$ at 800-900 K and exceeds the p-type PF primarily because of the higher electrical conductivity. Se vacancies ($V_{\mathrm{Se}}$) produce weaker electron-defect scattering than Sn vacancies ($V_{\mathrm{Sn}}$), and p-type transport is less defect tolerant than n-type transport in both phases. We define an operational critical defect concentration, $C_{\mathrm{crit}}$, at which the PF decreases by 15% relative to the corresponding defect-free value. The lowest $C_{\mathrm{crit}}$ is $8.841\times10^{-5}$ (approximately 88 ppm) for p-type $\alpha$-SnSe with $V_{\mathrm{Sn}}$; for n-type $\beta$-SnSe with $V_{\mathrm{Se}}$, the 15% threshold is not reached up to $5\times10^{-3}$ (5000 ppm). These results distinguish finite-temperature
phonon renormalization in stable $\alpha$-SnSe from anharmonic stabilization in $\beta$-SnSe and provide defect-concentration limits for preserving the PF.
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All authors Nguyen Tran Gia Bao, Thang Bach Phan, Vu Thi Hanh Thu, Nguyen Tuan Hung
Medical Physics
T2 estimation from MOLLI acquisitions
Catarina N Carvalho, Andreia S Gaspar, Rita G Nunes et al. (+1 more)
Cardiac T1 and T2 quantitative
magnetic resonance imaging (MRI) is a technique that provides characterization of a multitude of myocardial pathologies. However, each parameter requires its own specialized acquisition sequence, which may be time-consuming. In this work, we demonstrate that MOLLI, an acquisition sequence commonly used to perform T1 mapping, is also sensitive to T2, and can also be used for myocardial T2 mapping. Although MOLLI is not designed for T2 mapping, its signal
evolution inherently depends on both T1 and T2 relaxation. Here, we demonstrate that this dependence is sufficiently strong to allow T2 estimation directly from MOLLI T1-weighted images, using appropriate signal modelling. This finding opens the possibility of obtaining simultaneously T1 and T2 maps from a single MOLLI acquisition, reducing total scan time and potentially improving patient comfort and clinical throughput.
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All authors Catarina N Carvalho, Andreia S Gaspar, Rita G Nunes, Teresa M Correia
Optics
High-capacity computing with self-rectification nonlinear optical neural processor
Ruicheng Ma, Siyu Dong, Yuzhi Shi et al. (+14 more)
Artificial intelligence (AI) and neural networks have driven groundbreaking innovations across numerous disciplines. Optical computing offers the promise of unprecedented speed and energy efficiency in the post-Moore era; however, achieving efficient, practical nonlinear activation using all-optical approaches remains a challenge. Here, we present an optical nonlinear neural processing unit (ONNPU) that implements all-optical nonlinear activation through a self-rectification mechanism. The ONNPU architecture perfectly imitates the structure of digital neural networks, enabling seamless integration with the established deep learning ecosystem. We
benchmark ONNPU across nine diverse tasks spanning decision, regression and generation, including accuracies of 98.07% on MNIST and 93.54% on Fashion-MNIST. When integrated into a 201-million-parameter
Vision Transformer, ONNPU achieves 82.4% top-1 accuracy on full ImageNet classification (1,000 categories); when integrated into a 117-million-parameter decoder-only
Transformer, ONNPU enables short-form story generation that outperforms GPT-2. By addressing more complex and diverse deep learning tasks, ONNPU paves the way toward practical optical machine intelligence, unleashing significant potential for high-performance optical computing.
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All authors Ruicheng Ma, Siyu Dong, Yuzhi Shi, Yuchen Zhu, Hong Luo, Qiang Fu, Hadi Amata, Wolfgang Heidrich, Xiong Dun, Hongfei Jiao, Hui Zhang, Qinghua Song, Zeyong Wei, Zhanshan Wang, Ali Momeni, Romain Fleury, Xinbin Cheng
Plasma Physics
Gradient-Based Construction of Collisionless Steady-State Guiding-Center Distributions in Tokamaks and Stellarators
Jingyi Yu and Chang Liu
We present a
matrix-free residual-minimization method for preparing guiding-center distribution functions on finite grids. The method minimizes a fixed conservative discrete residual in the physical Jacobian metric using Polak-Ribiere+ iterations with exact quadratic line searches. JAX/XLA evaluates the operator and its adjoint without assembling a four-dimensional
matrix; independent
magnetic-moment slices are batched and iterations are compiled into one execution graph. An axisymmetric hierarchy verifies invariant references and tests the workflow using a NUBEAM fast-ion distribution together with an EPCoM constants-of-motion representation constructed from it, before matched precise quasi-axisymmetric (precise-QA), HSX, and W7-X calculations. The three-dimensional endpoints reduce the discrete residual and the finite-time variation of the distribution sampled along independently integrated characteristics. Non-negative projection is treated as an optional constrained extension: it leaves the residual operator unchanged but changes the feasible zero-residual set and endpoint selection. Results are finite-grid, finite-time evidence and do not establish a continuous
equilibrium, grid convergence, strict positivity, or a transport prediction.
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Optics
Power-Bandwidth Scaling of Resonantly Coupled Soliton Microcombs
Xinrui Luo, Kaixuan Zhu, Yuanlei Wang et al. (+8 more)
A
soliton microcomb requires increasing pump power as its optical bandwidth is broadened. Resonant pumping through an auxiliary microresonator can reduce the power required to sustain a
soliton, but simultaneously increases the power required for
soliton formation. We show that this competition leads to optimal inter-resonator coupling, and the predicted minimum input pump power scales as the two-thirds power of the comb bandwidth, in contrast to the quadratic scaling under direct pumping. Experiments support the opposing power trends, providing a design rule for power-efficient, ultra-broadband
soliton microcombs.
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All authors Xinrui Luo, Kaixuan Zhu, Yuanlei Wang, Yinke Cheng, Haoyang Luo, Junqi Wang, Yiwen Yang, Zhenyu Xie, Bei-Bei Li, Qihuang Gong, Qi-Fan Yang
Fluid Dynamics
Mean flow scaling in stably stratified temporally developing turbulent boundary layers
Baptiste Hardy and Pedro Costa
Stably stratified wall-bounded
turbulence governs the dynamics of many environmental and engineering flows. A key challenge is characterizing how stratification modifies mean and turbulent profiles. Monin–Obukhov similarity theory (MOST) is the dominant modelling framework, although it has rarely been rigorously validated against well-controlled direct numerical simulation (DNS) data over a wide range of stratification levels. In this study, we exploit the temporally developing turbulent boundary layer (TTBL) framework to investigate stratified turbulent boundary layers from the weakly stable to the very stable regime, spanning a range of Reynolds and Richardson numbers, and isolating the effects due to buoyancy from other mechanisms such as flow rotation. We demonstrate that the TTBL set-up faithfully reproduces classical similarity theory results and that surface-based scaling of the mean velocity gradient holds over a wider range of $z/L$ ($L$ being the Obukhov length) than previously reported. This result is attributed to the similar decay rate of turbulent shear stress and heat flux in this canonical flow. Next, we show that, as stratification intensifies, the intercept of the mean velocity profile increases, until the separation of scales required for a logarithmic region to exist can no longer be sustained. We propose an empirical closure for this intercept shift in terms of the Reynolds number based on the Obukhov length. Finally, a simple damping of the MOST contribution to the mean velocity profile is proposed and validated, enabling accurate prediction of the wall friction coefficient ($C_f$) across the investigated regimes.
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Optics
Broadband transverse mode directional couplers using partial Euler bends
Airin Antony, Daniel Peace and Jacquiline Romero
Transverse modes beyond the fundamental mode are increasingly being explored to increase information capacity in both mode-division multiplexing and high-dimensional
quantum information processing. The ability to combine and separate these modes at arbitrary ratios over a broad bandwidth is central to these applications. Motivated by the lower bending loss and intermodal crosstalk of partial Euler bends in multimode waveguides, we develop a
geometric framework based on partial Euler bends for broadband power coupling between the first two transverse electric modes on a silicon-on-
insulator platform. Our methodology uses a hybrid of eigenmode expansion and finite-difference time-domain methods. Our designs feature a mode (de)multiplexer, as well as unbalanced couplers (2/3 and 1/3 splitters). The simulated 1-dB bandwidths of our directional couplers range from $101$ nm to $134$ nm. The best-performing fabricated mode (de)multiplexer has a measured 1-dB bandwidth of $90$ nm, a conversion efficiency of $94.0\%$ and crosstalk below $-18$ dB at $1550$ nm. Our results validate the use of partial Euler bends for broadband transverse mode directional couplers and provide a general framework for their design.
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Atomic and Molecular Clusters
Hydrogen isotope mixing entropy in ammonia clusters
Klavs Hansen, Åke Andersson, Johannes Reichegger et al. (+2 more)
Measured evaporation branching ratios of partially deuterated isotopologues of protonated ammonia clusters (NH$_3$)$_N$ H$^+$ ($N \geq 8$) show ratios that depend only on the clusters' deuterium mole fraction. This demonstrates randomly distributed protium and deuterium in the molecules and can be used to determine free energy differences in the product cluster. The
entropy thus determined is exclusively the deuterium-protium mixing
entropy. The relative dissociation energies of the four isotopologues are determined and with the support of
quantum chemistry calculations, their absolute values are estimated.
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All authors Klavs Hansen, Åke Andersson, Johannes Reichegger, Siegfried Kollotzek, Paul Scheier
Atomic Physics · Cross-listed from cond-mat.quant-gas
Odd/Even or Half ? Entanglement Anomaly in the Bose-Hubbard model
Humberto E. López-Hernández and Santiago F. Caballero-Benitez
The area law relates the bipartite
entanglement entropy of a
quantum many-body ground state to the size of the boundary between the subsystems, but the geometry of this boundary is rarely discussed. We inspect this in the 1D Bose-Hubbard model at fixed density by comparing four spatial bipartitions of the periodic
lattice: first half, second half, even sites, and odd sites; sharing the same number of sites but differing in how the boundary is arranged. We find analytical limits with perturbation theory: in the Mott
insulator the contiguous cut obeys the area lay while the alternating cut obeys a volume law $S\propto N_s$, in this sense an anomaly, and for the superfluid both cuts colapse to the binomial saturation due to delocalization of the state. We formulate these limits as a statement about the many-body problem using a generalized slave-
boson approach based on mean-field with
quantum fluctuations while verifying with Exact Diagonalization (ED) for small
lattice sizes and Densitiy
Matrix Renormalization Group (DMRG) simulations for $N_s\gg 1$. The slave-
boson Gaussian ground state allows to compute the
entanglement entropy from a reduced correlation
matrix for any desired bipartition consistent with ED and DMRG results. Using slave
bosons the computational cost is set by the local cutoff $n_{\max}$ rather than the
Hilbert space dimension, so we can reach
lattice sizes far beyond ED. Our method is capable of establishing the partition-dependent scaling laws as a many-body feature, not only a finite-size effect, in great agreement with the ED for $N_s\in[4,10]$ and DMRG for larger
lattice sizes.
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Optics
Mo2TiC2Tx MXene Saturable Absorption for Neural Networks on a Chip
Shadad Watad, Aviad Katiyi, Bar Favelukis et al. (+5 more)
MXenes have attracted considerable interest for integrated nonlinear photonics owing to their broadband optical response and chemical tunability, yet investigations have focused predominantly on Ti-based compositions, leaving the nonlinear potential of double-transition-metal MXenes largely unexplored. Here we quantify the nonlinear optical response of the double-transition-metal MXene \ce{Mo2TiC2T_x} and demonstrate its functionality as a waveguide-integrated nonlinear activation element for neuromorphic photonics. Z-scan measurements at \SI{800}{\nano\metre} reveal strong saturable absorption in films of two different thicknesses, yielding effective nonlinear absorption coefficients ($\beta_\mathrm{eff}$) between approximately $-2.69\times10^{3}$ and $-0.88\times10^{3}$ \si{\centi\metre\per\giga\watt}, with the nonlinear response decreasing at higher excitation intensities. The extracted nonlinear absorption is approximately one order of magnitude larger than that reported for \ce{Ti3C2T_x} MXene under comparable conditions. We integrate an ultrathin \ce{Mo2TiC2T_x} MXene layer onto a silicon rib waveguide to realize a compact nonlinear optical activation function, which, when implemented in a neural-network emulator, achieves $98.39\%$ classification accuracy on the MNIST
benchmark. This work expands the MXene material platform beyond Ti-based compositions and establishes double-transition-metal MXenes as promising candidates for high-performance integrated nonlinear photonic and neuromorphic computing technologies.
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All authors Shadad Watad, Aviad Katiyi, Bar Favelukis, Muhammad Sharif Uddin, Anupma Thakur, Maxim Sokol, Babak Anasori, Alina Karabchevsky
Computational Physics · Cross-listed from cond-mat.mtrl-sci
The Roadmap of Inorganic Computational Materials Databases: Capabilities, Credibility, Coverage, and the Open Frontier
Miao Liu, Jianghao Jin, Tenglong Lu et al. (+4 more)
Computational materials databases have become central infrastructure for data-driven discovery of inorganic materials, yet their growth remains strikingly uneven across property families. This perspective synthesizes a systematic survey of mainstream density functional theory (DFT) software, the computational cost and credibility of nineteen material-property families, and the coverage of existing computational databases, into a coherent picture of where the field stands and where it should go. We show that the ecosystem of first-principles codes is methodologically mature: for nearly every property of technological interest, at least one production-grade code can compute it.The binding constraint is no longer methodological capability but the economics of trust - which properties can be computed cheaply enough, and accurately enough, to be harvested at database scale. Mapping database coverage onto a Gartner-style readiness cycle reveals a sharp divide: ground-state structure, energetics, elasticity, and
topology have reached routine production, while nine property families - including NMR/EPR parameters, core-level spectra, electron-
phonon properties, thermal conductivity, and
quantum transport - remain without any systematic computational database. We argue that these blank zones define the scientific opportunity of the next decade, and we propose a three-horizon roadmap: consolidating coverage and interoperability in the near term, industrializing mid-cost properties through surrogate-accelerated workflows in the medium term, and conquering the high-cost frontier through machine-learned interatomic potentials, autonomous computing infrastructure, and community governance in the long term.
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All authors Miao Liu, Jianghao Jin, Tenglong Lu, Jianguo Si, Yin Shi, Sheng Meng, Weihua Wang
Fluid Dynamics
Mixed-precision GPU algorithms for efficient turbulent flow simulations with Raviart-Thomas finite elements
Ivan Prusak, Enes Mustafa Soydan, Ivan Pribec et al. (+1 more)
We propose GPU
algorithms for high-fidelity simulation of incompressible turbulent flows. Discretization in space is performed with H(div)-conforming high-order Raviart-Thomas finite elements for the velocity and an $L^2$-conforming discontinuous Galerkin approximation for the pressure. In time, a consistent splitting scheme based on higher-order BDF time stepping is used, with convection treated explicitly. In this scheme, a pressure Poisson equation and a symmetric reaction-
diffusion-type equation for the velocity need to be solved in each time step. We develop a solution framework with fast
matrix-free operator evaluation for all ingredients, combined with multigrid solvers for the Poisson problem, and propose a robust mixed-precision algorithmic framework. A key to mixed-precision efficiency is a least-squares projection to generate accurate initial guesses for the iterative linear solvers, enabling us to work with relative residual tolerances of $10^{-3}$. In this regime, running the solvers entirely in single precision leads to almost no change in overall iteration counts and maintains the crucial
turbulence statistics, while showing up to $1.7\times$ speedup over pure double-precision simulations.
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All authors Ivan Prusak, Enes Mustafa Soydan, Ivan Pribec, Martin Kronbichler
Computational Physics
Exergy-Anergy Representation of Turbomachine Performance Characteristics
Tihomir Varchev, Yiwen Yuan, Tobias Schateikis et al. (+1 more)
The performance synthesis calculation of aircraft engines relies on tabulated
datasets for the simulation of the complex turbomachinery components at acceptable runtimes. Typically, these so-called performance maps express the change of the fluid's energetic state over the component in terms of the total pressure ratio and the isentropic efficiency of the process. However, the definitions of both parameters are different for compressors and turbines and the isentropic efficiency is in both cases not defined for a unity pressure ratio. Moreover, this parameter combination is not directly applicable when modelling the engine at the aircraft level, which is required for modern highly integrated aircraft design. As exergy analysis is an established tool for aircraft design asessment, novel performance maps are proposed that describe the change in exergy and anergy over a given turbomachine component. Both changes are expressed as non-dimensional parameters whose definition is consistent for compressors and turbines, and is compatible with a unity pressure ratio. It is shown that the presented exergy-anergy maps are obtainable on a standard turbomachine test bed or through transformation of existing maps. It is highlighted using examples, that the conversion between existing maps and exergy-anergy maps is completely lossless. The different operating regimes of the turbomachines are clearly distinguishable in the novel map representation, which allows an assessment of the map's physical consistency. It is therefore concluded, that the exergy-anergy maps are an important alternative to the performance map variants established today.
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All authors Tihomir Varchev, Yiwen Yuan, Tobias Schateikis, Stephan Staudacher