Chemical Physics
onepot CORE – an enumerated chemical space to streamline drug discovery, enabled by automated small molecule synthesis and AI
Andrei S. Tyrin, Brandon Wang, Manuel Muñoz et al. (+2 more)
The design-make-test-analyze cycle in early-stage drug discovery remains constrained primarily by the "make" step: small-molecule synthesis is slow, costly, and difficult to scale or automate across diverse chemotypes. Enumerated chemical spaces aim to reduce this bottleneck by predefining synthesizable regions of chemical space from available building blocks and reliable reactions, yet existing commercial spaces are still limited by long turnaround times, narrow reaction scope, and substantial manual decision-making in route selection and execution. Here we present the first version of onepot CORE, an enumerated chemical space containing 3.4B molecules and corresponding on-demand synthesis product enabled by an automated synthesis platform and an AI chemist, Phil, that designs, executes, and analyzes experiments. onepot CORE is constructed by (i) selecting a reaction set commonly used in medicinal chemistry, (ii) sourcing and curating building blocks from supplier catalogs, (iii) enumerating candidate products, and (iv) applying ML-based feasibility assessment to prioritize compounds for robust execution. In the current release, the space is supported by seven reactions. We describe an end-to-end workflow - from route selection and automated
liquid handling through workup and purification. We further report validation across operational metrics (success rate, timelines, purity, and identity), including NMR confirmation for a representative set of synthesized compounds and assay suitability demonstrated using a series of DPP4 inhibitors. Collectively, onepot CORE illustrates a path toward faster, more reliable access to diverse small molecules, supporting accelerated discovery in pharmaceuticals and beyond.
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All authors Andrei S. Tyrin, Brandon Wang, Manuel Muñoz, Samuel H. Foxman, Daniil A. Boiko
Chemical Physics
Thermodynamic principles of emerging cryopreservation technologies
Matthew J. Powell-Palm and Anthony N. Consiglio
Modern cryopreservation exists at the convergence of diverse disciplines–materials science, physical chemistry, mechanical engineering, biological engineering, etc.–and emerging technologies often draw from many of these disciplines simultaneously. Thermodynamics, as one of the foundational theories underlying both physical and biological science, provides a framework through which to understand these interdisciplinary technologies, yet the full kit of requisite thermodynamic tools is not housed within any one discipline. This Chapter aims to articulate a foundational thermodynamic approach to the description, interrogation, and design of modern cryopreservation technologies, and to review the state of the art in emerging cryopreservation technologies through the lens of this approach. We focus in particular on the management of phase change across
equilibrium-driven techniques (e.g., liquidus tracking, partial freezing, isochoric freezing), kinetics-driven techniques (e.g. supercooling, ice seeding), and transport-driven techniques (e.g. directional freezing, droplet approaches), and we hope to equip the reader with a self-consistent theoretical toolkit that enables meaningful comparison of these techniques from a thermodynamic perspective.
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Chemical Physics · Cross-listed from cond-mat.mtrl-sci
INTERFACE Force Field for Alumina with Validated Bulk Phases and a pH-Resolved Surface Model Database for Aqueous, Electrolyte, and Molecular Interfaces
Cheng Zhu, Krishan Kanhaiya, Samir Darouich et al. (+7 more)
Alumina and aluminum oxyhydroxides underpin numerous chemical engineering technologies in heterogeneous catalysis, corrosion protection, functional coatings, energy storage devices, and biomedical components. Yet molecular models that predictively connect phase structure, pH dependent surface chemistry, electrolyte organization, and adsorption across operating conditions remain limited. Here we introduce the INTERFACE Force Field (IFF) together with a curated, ready-to-use pH-resolved surface model database for an accurate and transferable atomistic description of major alumina phases according to experimental
benchmarks available. The framework covers alpha-Al2O3, gamma-Al2O3, boehmite, diaspore, and gibbsite using a single parameter set compatible with CHARMM, AMBER, OPLS-AA, CVFF, and PCFF. Simulations reproduce experimental reference data across structural, thermodynamic, mechanical, and interfacial
benchmarks with deviations of few percent relative to experiment, exceeding existing force fields and density-functional approaches. We introduce a transferable treatment of surface ionization and charge regulation across alumina phases over a broad pH range, enabling simulations of realistic solid-electrolyte interfaces without phase-specific reparameterization. Quantitative reliability is demonstrated by reproducing
zeta-potential trends and pH-dependent adsorption of an organic corrosion inhibitor at alumina-water interfaces. Predicted adsorption free energies and surface contact times correlate with experiments across an order of magnitude, enabling process-relevant screening and explaining limitations of earlier adsorption models. The approach is 10,000 to 100,000 times faster than DFT-machine learned interatomic potentials (MLIPs) and supports the design of alumina-containing catalysts, corrosion-resistant coatings, energy storage and biomaterials under realistic process conditions.
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All authors Cheng Zhu, Krishan Kanhaiya, Samir Darouich, Sean P. Florez, Karnajit Sen, Patrick Keil, Nawel S. Khelfallah, Eduard Schreiner, Ratan K. Mishra, Hendrik Heinz
Optics
Minimal-footprint photonic crystal nanolasers for biointegration
Catriona A. Thomson, Andreas Stühler, Nachiket Pathak et al. (+2 more)
Photonic
crystals allow unprecedented control over how light is confined, propagates, and interacts with matter. Their development has had a transformative impact on optics and physics, and they remain the central platform for both fundamental discoveries and practical photonic technologies. However, the relatively large footprint and substrate-bound nature of photonic
crystal structures have so far strongly limited their use as miniature optical devices or biointegrated sensors. Here, we overcome these limitations by identifying the minimal size of a 2D photonic
crystal array needed to achieve lasing and describe the fabrication of substrate-less hexagonal
laser particles with an active area as small as 30 {\mu}m2. Massively parallel fabrication, robust detachment, and integration of the nanolaser particles into live
cells is demonstrated. Crucially, by engineering spatial and spectral mode characteristics, we designed NIR-II probes with mode volumes on the order of tens of attolitres, an order of magnitude smaller than whispering gallery probes of similar dimensions. Such high light localization is comparable in scale to different organelles of eucaryotic
cells. In the future, we expect that chemical or plasmonic functionalization of the device will enable label-free sensing of nanoscale intracellular processes, and that it shall serve as a miniature platform to exploit developments in optical and
quantum sensing for chemical and biological applications.
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All authors Catriona A. Thomson, Andreas Stühler, Nachiket Pathak, Valeryia Dzikevich, Marcel Schubert
Computational Physics · Cross-listed from cond-mat.mtrl-sci
Artificial Intelligence in Materials Science and Engineering: Current Landscape, Key Challenges, and Future Trajectorie
Iman Peivaste, Salim Belouettar, Francesco Mercuri et al. (+15 more)
Artificial Intelligence is rapidly transforming materials science and engineering, offering powerful tools to navigate complexity, accelerate discovery, and optimize material design in ways previously unattainable. Driven by the accelerating pace of algorithmic advancements and increasing data availability, AI is becoming an essential competency for materials researchers. This review provides a comprehensive and structured overview of the current landscape, synthesizing recent advancements and methodologies for materials scientists seeking to effectively leverage these data-driven techniques. We survey the spectrum of machine learning approaches, from traditional
algorithms to advanced deep learning architectures, including CNNs, GNNs, and
Transformers, alongside emerging generative AI and probabilistic models such as Gaussian Processes for uncertainty quantification. The review also examines the pivotal role of data in this field, emphasizing how effective representation and featurization strategies, spanning compositional, structural, image-based, and
language-inspired approaches, combined with appropriate preprocessing, fundamentally underpin the performance of machine learning models in materials research. Persistent challenges related to data quality, quantity, and standardization, which critically impact model development and application in materials science and engineering, are also addressed.
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All authors Iman Peivaste, Salim Belouettar, Francesco Mercuri, Nicholas Fantuzzi, Hamidreza Dehghani, Razieh Izadi, Halliru Ibrahim, Jakub Lengiewicz, Maël Belouettar-Mathis, Kouider Bendine, Ahmed Makradi, Martin Hörsch, Peter Klein, Mohamed El Hachemi, Heinz A. Preisig, Yacine Rezgui, Natalia Konchakova, Ali Daouadji
Instrumentation and Detectors
Design Optimization of Triple Gas Electron Multiplier for Superior Gain and Reduced Ion Backflow
Sachin Rana, Md. Kaosor Ali Mondal, Poojan Angiras et al. (+1 more)
Micro-Pattern Gas Detectors (MPGDs) are extensively employed in modern high-energy and
nuclear Physics experiments because of their excellent spatial resolution, high rate capability, and operational stability. Among these, the Gas Electron Multiplier (GEM) has emerged as one of the most widely adopted MPGD technologies. Despite their widespread adoption, GEM detectors based on the conventional bi-conical hole geometry do not always achieve optimal performance, particularly in maximizing effective gain while suppressing ion backflow. One of the primary factors limiting a GEM's performance is ion backflow. The accumulation and gradual discharge of these ions might alter the local electric field, resulting in a temporary dead time and complicating responses to subsequent events. These limitations pose challenges for applications requiring high precision and stable long-term operation. In this work, we address these issues by investigating modified GEM geometries designed to enhance gain performance and reduce ion backflow, thereby improving overall detector performance. The current study investigates
geometric optimization strategies for a triple-GEM detector to enhance performance, mitigate ion backflow, and augment gain. The detector structures were designed using the ANSYS Mechanical APDL, and the associated electrostatic field configurations were computed using the ANSYS Maxwell. A thorough investigation of gain and ion backflow calculations was carried out when the generated field maps were interfaced with Garfield$^{++}$. The potential enhancements in detector efficiency and stability that the proposed modifications to the GEM foil geometry offers a valuable insights for the design of next-generation gaseous detectors.
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All authors Sachin Rana, Md. Kaosor Ali Mondal, Poojan Angiras, Amal Sarkar
Fluid Dynamics
Unified multifractal description of longitudinal and transverse intermittency in fully developed turbulence
Dhawal Buaria
Small-scale intermittency is a defining feature of fully developed fluid
turbulence, marked by rare and extreme fluctuations of velocity increments and gradients that defy mean-field descriptions. Existing multifractal descriptions of intermittency focus primarily on longitudinal increments and gradients, despite mounting evidence that transverse components exhibit distinct and stronger intermittency. Here, we develop a unified multifractal framework that jointly prescribes longitudinal and transverse velocity increments, and extends to gradients. We derive explicit relations linking inertial-range scaling exponents of structure functions to moments of velocity gradients in dissipation range. Our results reveal that longitudinal gradient scaling is solely prescribed by longitudinal structure functions, as traditionally expected; however, transverse gradient scaling is prescribed by mixed longitudinal-transverse structure functions. Validation with high-resolution direct numerical simulations of isotropic
turbulence, at Taylor-scale Reynolds number up to $1300$ demonstrates excellent agreement, paving way for a more complete and predictive description of intermittency faithful to the underlying
turbulence dynamics.
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Instrumentation and Detectors
Beam test studies for a SiPM-based RICH detector prototype for the future ALICE~3 experiment
A. R. Altamura, L. Congedo, G. De Robertis et al. (+14 more)
The ALICE Collaboration is proposing a completely new apparatus, ALICE~3, for the LHC Runs~5 and beyond. In this context, a key subsystem for high-energy charged particle identification will be a proximity-focusing ring-imaging Cherenkov detector using aerogel as radiator and silicon photomultipliers (SiPMs) as
photon sensors. We assembled a small-scale prototype instrumented with Hamamatsu S13352 and S13361-3075AE-08 SiPM arrays, readout by custom boards equipped with front-end Petiroc 2A ASICs. The Cherenkov radiator consisted of a 2 cm thick hydrophobic aerogel tile with a refractive index of 1.03 separated from the SiPM plane by a 23 cm expansion gap. The prototype was successfully tested in a campaign at the CERN PS T10 beam line with the goal of validating the design bRICH specifications in terms to achieve the target separation power. We measured a single
photon angular resolution of 3.8~mrad at the Cherenkov angle saturation value of 242~mrad, as well as the expected scaling of the angular resolution with the increasing number of detected
photons. We also studied the contribution of uncorrelated and correlated background sources with respect to the signal and proved the effectiveness of time matching between charged tracks and
photon hits to achieve efficient suppression of the SiPM dark count rate background. In this paper, the detector concept, the description of the tested prototype layout and the main beam test results are reported.
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All authors A. R. Altamura, L. Congedo, G. De Robertis, D. Di Bari, A. Di Mauro, M. Giliberti, J. O. Guerra-Pulido, F. Licciulli, L. Lorusso, P. Martinengo, M. N. Mazziotta, E. Nappi, N. Nicassio, G. Paic, G. Panzarini, R. Pillera, G. Volpe
Instrumentation and Detectors
Test beam performance of a novel RICH detector with timing capabilities for the future ALICE~3 PID system at LHC
M. N. Mazziotta, L. Congedo, G. De Robertis et al. (+9 more)
The ALICE Collaboration is proposing a completely new apparatus, ALICE 3, for the LHC Run 5 and beyond. A key subsystem for charged particle identification will be a Ring-Imaging Cherenkov (RICH) detector consisting of an aerogel radiator and a photosensitive surface based on Silicon Photomultiplier (SiPM) arrays in a proximity-focusing configuration. A thin high-refractive index slab of transparent material (window), acting as a second Cherenkov radiator, is glued on the entrance face of the SiPM arrays to achieve precise charged particle timing. Requiring time matching between aerogel Cherenkov
photon and track hits leads to an improvement of pattern recognition by discarding the uncorrelated SiPM dark count hits. In this work we present the current status of the R&D performed for the ALICE 3 RICH detector prototype and the expected full scale system performance. A special focus will be given to the beam test results obtained with a small-scale prototype instrumented with various array of Hamamatsu SiPMs with pitches ranging from 1 to 3 mm. The Cherenkov radiator consisted of a 2 cm thick aerogel tile with a refractive index of 1.03 at 400 nm wavelength. For timing measurements SiPM arrays coupled with two different window materials (SiO$_2$ and MgF$_2$) were used. The prototype was successfully tested in beam test campaigns at the CERN PS T10 beam line. The data were collected with a complete chain of front-end and readout electronics based on the Petiroc 2A and Radioroc 2 together with a picoTDC to measure charges and times. We measured a charged particle detection efficiency above 99% and a single
photon angular resolution better than 4.2 mrad at the Cherenkov angle saturation with a time resolution better than 70 ps for charged particles.
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All authors M. N. Mazziotta, L. Congedo, G. De Robertis, A. Di Mauro, F. Licciulli, L. Lorusso, P. Martinengo, E. Nappi, N. Nicassio, G. Panzarini, R. Pillera, G. Volpe
Chemical Physics · Cross-listed from cond-mat.mtrl-sci
A non-equilibrium strategy for the general synthesis of single-atom catalysts
Yue Li, Yang Xu, Yunbiao Zhao et al. (+6 more)
Single-atom catalysts (SACs) maximize atom efficiency and exhibit unique electronic structures, yet realizing precise and scalable atomic dispersion remains a key challenge. Here, we report a non-
equilibrium strategy for the scalable synthesis of SACs via ion implantation, enabling precise stabilization of metal atoms on diverse supports. Using an industrial-grade ion source, wafer-scale ion implantation with milliampere-level beam currents enables high-throughput fabrication of SACs, while the synergistic energy-mass effects stabilize isolated metal atoms in situ. A library of 36 SACs was constructed, and the resulting Pt/MoS2 exhibits outstanding hydrogen
evolution performance with an overpotential of only 26 mV at 10 mA cm-2 and exceptional long-term stability, surpassing commercial Pt/C. This work demonstrates ion implantation as a versatile platform bridging fundamental SACs design and scalable manufacturing, providing new opportunities for high-performance catalysts in energy conversion applications.
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All authors Yue Li, Yang Xu, Yunbiao Zhao, Mingwei Cui, Xiner Chen, Liu Qian, Jin Zhang, Xueting Feng, Ziqiang Zhao
Plasma Physics · Cross-listed from astro-ph.SR
Evidence of energy conversion in weakly collisional plasma during an interplanetary coronal mass ejection
Omkar Dhamane, Anil Raghav, Simone Benella et al. (+14 more)
Intervals of enhanced turbulent fluctuations are typically less frequent within the
magnetic cloud region of an interplanetary coronal mass ejection (ICME). We investigate two such intervals inside an ICME observed by the Wind spacecraft on 8–9 June 2000 and characterize their associated wave populations. We focus on spectral analysis and
plasma instability analysis, using ion-scale normalized
magnetic helicity and polarization properties with respect to the background
magnetic field $B_0$. In the first interval, the ion-scale normalized
magnetic helicity shows a left-handed circularly polarized signature. In the second interval, the left-handed signature persists and an additional high-frequency right-handed population appears. The propagation is approximately parallel to $B_0$. The left-handed fluctuations are compatible with Alfvén ion-cyclotron (AIC) waves, while the right-handed fluctuations are consistent with fast magnetosonic/whistler (FM/W) waves. The ICME
plasma accesses resonance conditions that support multiple ion-scale wave modes. Evolving anisotropies in the
plasma and the approach to marginal stability allow the coexistence of AIC-like and fast-magnetosonic/whistler-like fluctuations, with enhanced electron heating favoring the growth of the FM/W contribution and strengthening the density–
magnetic-field magnitude correlation.
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All authors Omkar Dhamane, Anil Raghav, Simone Benella, Kishor Kumbhar, Raffaella D'Amicis, Oreste Pezzi, Utkarsh Sharma, Ashok Silwal, Panini Maurya, Mirko Stumpo, Kalpesh Ghag, Ajay Kumar, Mohit Shah, Mariyam Karari, Lynn B. Wilson III, Jia Huang, Daniele Telloni
Instrumentation and Detectors
Development of a novel compact and fast SiPM-based RICH detector for the future ALICE 3 PID system at LHC
M. N. Mazziotta, A. R. Altamura, L. Congedo et al. (+12 more)
A dedicated R&D is ongoing for the charged particle identification system of the \mbox{ALICE 3} experiment proposed for the LHC Run 5 and beyond. One of the subsystems for the high-energy charged particle identification will be a Ring-Imaging Cherenkov (RICH) detector. The possibility of integrating Cherenkov-based charged particle timing measurements is currently under study. The proposed system is based on a proximity-focusing RICH configuration including an aerogel radiator separated from a SiPM array layer by an expansion gap. A thin high-refractive index window of transparent material, acting as a second Cherenkov radiator, is glued on the SiPM array to enable time-of-flight measurements of charged particles by exploiting the yield of Cherenkov
photons in the thin window. We assembled a small-scale prototype instrumented with different Hamamatsu SiPM array sensors with pitches ranging from 1 to 3 mm, readout by custom boards equipped with the front-end Petiroc 2A ASICs to measure charges and times. The primary Cherenkov radiator consisted of a 2 cm thick aerogel tile, while various window materials, including SiO$_2$ and MgF$_2$, were used as secondary Cherenkov radiators. The prototype was successfully tested in a campaign at the CERN PS T10 beam line with pions and
protons. This paper summarizes the results achieved in the 2023 test beam campaign.
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All authors M. N. Mazziotta, A. R. Altamura, L. Congedo, G. De Robertis, A. Di Mauro, J. O. Guerra-Pulidoc, F. Licciulli, L. Lorusso, P. Martinengo, E. Nappi, N. Nicassio, G. Paic, G. Panzarini, R. Pillera, G. Volpe
Optics
Stabilizing van der Waals NbOI2 by SiO2 encapsulation for Photonic Applications
Gia Quyet Ngo, Fatemeh Abtahi, Jakub Regner et al. (+6 more)
Niobium
oxide diiodide (NbOI2) is an emerging material for photonics and electronics, distinguished by its exceptional second-order nonlinearity and pronounced in-plane ferroelectricity, both originating from its highly anisotropic ABC-stacked
crystal structure. Its broken inversion
symmetry enables its optical nonlinear efficiency to scale with thickness, making multilayer NbOI2 highly promising for nonlinear frequency conversion like second harmonic generation or and spontaneous parametric down-conversion in bulk or waveguides. However, under ambient conditions NbOI2 degrades into an amorphous
oxide within weeks, severely diminishing its nonlinear response. To overcome this, we investigate SiO2 encapsulation via physical vapor deposition to protect NbOI2 multilayers from environmental degradation. Our systematic study reveals that encapsulation preserves structural integrity and nonlinear optical performance, establishing NbOI2 as a stable candidate for heterogeneous integration in foundry-compatible photonic platforms and
quantum technologies.
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All authors Gia Quyet Ngo, Fatemeh Abtahi, Jakub Regner, Hossein Esfandiar, Peter Munzert, Jan Plutnar, Zdenek Sofer, Falk Eilenberger, Sebastian W. Schmitt
Plasma Physics
SPARC Tokamak Error Field Expectations and Physics-Based Correction Coil Design
N.C. Logan, C.E. Myers, R. Sweeney et al. (+6 more)
Non-axisymmetric
magnetic field coils have been designed to provide efficient error field correction and suppress edge localized modes in SPARC - a compact high-field tokamak that is presently under construction at Commonwealth Fusion Systems. These designs utilize the Generalized Perturbed
Equilibrium Code's (GPEC's) representation of the multi-modal, non-axisymmetric
plasma response to optimize the
geometric coupling between 3D coil arrays and the desired core or edge
plasma response. Error field correction coils are designed to couple to the
plasma-amplified kink that dominates the drive of core resonances. The maximum allowable error field is projected to SPARC using an empirical scaling that is consistent with linear and nonlinear MHD modeling expectations. Asymmetric construction and assembly tolerances are then balanced against the corresponding kA-turns needed for correction to levels below the allowable limit. These physics-driven coil designs provide confidence in our ability to operate SPARC in new high field tokamak regimes without error field induced locked modes.
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All authors N.C. Logan, C.E. Myers, R. Sweeney, C. Paz-Soldan, M. Pharr, N. Leuthold, M. Nickerson, J. Halpern, I. Stewart
Plasma Physics
Plasmoid formation via competing lower-hybrid drift and Kelvin-Helmholtz instabilities: A hybrid kinetic-gyrokinetic simulation study
S. Thatikonda, F. N. De Oliveira-Lopes, A. Mustonen et al. (+3 more)
We investigate the nonlinear formation of plasmoids in 2D low-beta current sheets through the interplay between the Kelvin-Helmholtz instability (KHI) and the lower-hybrid drift instability (LHDI). Using a hybrid kinetic-gyrokinetic model-based Super Simple Vlasov (ssV) code with fully kinetic ions and drift-kinetic electrons, we simulate Harris-type current sheets and velocity shear layers with strong cross-field density gradients. Our central hypothesis is that steep density gradients drive LHDI, which can grow faster than KHI and initiate an inverse cascade from kinetic to fluid scales, potentially suppressing KHI. Our simulations confirm that, in thin current sheets, LHDI develops rapidly at the sheet edges and nonlinearly merges into larger-scale
magnetic islands before KHI can evolve. These LHDI-driven structures distort the velocity shear and suppress classical KH
vortices. In contrast, for thicker current sheets or weaker density gradients, KHI dominates and produces the expected rolled-up
vortices and associated plasmoids. These findings demonstrate that LHDI-induced
turbulence can act as both a seed and a regulator of plasmoid-generating instabilities, mediating cross-scale energy transfer. This mechanism is relevant to thin boundary layers in space
plasmas, such as the
solar wind magnetosphere interface, and suggests that microturbulence can govern large-scale
magnetic topology during collisionless reconnection.
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All authors S. Thatikonda, F. N. De Oliveira-Lopes, A. Mustonen, K.Pommois, D. Told, F. Jenko
Optics
Mixtenna: A Self-Biased Nonlinear Patch Antenna for Passive Third-Harmonic Radiation
Yishai Brill and Yakir Hadad
A nonlinear rectangular patch
antenna (RPA) is presented in which back-to-back Schottky diodes are embedded at high-field regions to enable passive, bias-free harmonic generation. The self-biased diodes introduce a power-dependent impedance that drives efficient frequency up-conversion and selective third-harmonic radiation. A tailored matching network enhances third-harmonic excitation and coupling while preserving radiation efficiency at the fundamental frequency. Analytical modeling combined with SPICE-assisted full-wave time-domain simulations predicts strong odd-harmonic content, and measurements on RPA prototypes employing SMS7630 diodes confirm these results. Simulated and measured S-parameters and far-field patterns at 925 MHz and 2.775 GHz show excellent agreement. The demonstrated approach establishes nonlinear loading as an effective mechanism for passive harmonic control in compact radiators, enabling frequency-agile and spectrum-efficient
antenna systems.
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Computational Physics · Cross-listed from nucl-th
Revisiting $^7$Be Weak and Radiative Transition Rates in Big Bang Nucleosynthesis: Implications for the Primordial Lithium Problem
Simone Taioli, Francesca Triggiani and Stefano Simonucci
The
primordial 7Li abundance predicted by standard Big Bang nucleosynthesis (BBN) exceeds observations in old, metal-poor
stars by a factor of 3-4. Since most
primordial 7Li is produced as 7Be and subsequently converted by electron capture (EC), additional 7Be destruction channels may affect its final abundance. We investigate EC and antineutrino capture (AC), positron decay from the 7Be
nuclear excited state, and
proton capture (PC), including 7Be(p,gamma)8B, stimulated emission (SE),
plasma screening, and a three-body Auger-like channel transferring the capture energy to a continuum electron. Weak rates are calculated from first principles using perturbation theory with explicitly evaluated hadronic and leptonic currents, while thermally averaged
nuclear rates are obtained from the relevant cross sections over 10 < kT < 100 keV. The EC rate rapidly decreases as the Universe expands and cools, while AC enhances weak destruction mainly at early times. SE and screening increase the 7Be(p,gamma)8B rate by only 1-3% at kT about 87 keV. The Auger-like cross section is about 4 x 10^-3 of the radiative channel at kT = 100 keV and falls to about 10^-10 at 10 keV. Our first-principles weak rates differ substantially from previous log(ft)-based estimates, yielding a 7Be half-life of about two days under BBN conditions, nearly one order of magnitude different from phenomenological predictions. Nevertheless, EC, PC, and beta+ decay provide only percent-level corrections to the dominant 7Be(n,p)7Li channel and cannot resolve the cosmological lithium problem. These results motivate a first-principles reassessment of the full BBN
nuclear network before invoking physics beyond the Standard Model.
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Medical Physics
Wavefront Shaping of Ultrasound Vortex through the Human Skull Enabled by Binary Acoustic Metasurfaces
Zhongtao Hu
Ultrasound
vortices have rapidly expanded their applications to areas like particle trapping, contactless manipulation, acoustic communications. In ultrasonic imaging and therapy involving bone tissues, these
vortex beams offer intriguing possibilities but transmitting them through bone (especially the skull) poses challenges. Traditional acoustic lenses were engineered to rectify skull-induced beam aberration, and their capacity was limited to generating only static ultrasound fields within the
brain. To overcome this constraint, our study presents a novel method for transcranially steering focused ultrasound
vortex using 3D printed binary acoustic metasurfaces (BAMs) with a thickness of 0.8 {\lambda}. We tackled the challenge of skull-induced phase aberration by computing the phase distribution via a time reversal technique, which concurrently enabled the generation of a steerable focused
vortex inside an ex vivo human skull by adjusting the operating frequency. Both numerical and simulations experiments were conducted to validate the capabilities of BAMs. Furthermore, we explored the generation of higher-order topological charge acoustic
vortices within the
brain utilizing the BAM. This development paves the way for designing cost-effective particle-trapping systems, facilitating clot manipulation, and applying acoustic-radiation forces and torques within or across bone structures, thus presenting a new frontier for potential biomedical applications.
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Optics
Saturable absorption in NV-doped diamond studied by femtosecond Z-scan
Wojciech Talik, Mariusz Mrózek, Adam M. Wojciechowski et al. (+1 more)
We investigate nonlinear optical absorption in diamond
crystals containing high densities of nitrogen vacancy (NV) centers using open-aperture Z-scan measurements with 230 fs
laser pulses at 1032 nm, within the transparency window of diamond. While high-purity electronic-grade diamond exhibits third-order nonlinear absorption, NV-doped samples display pronounced saturable absorption that strengthens with increasing defect concentration. Linear transmission spectroscopy reveals that, in addition to NV centers, the
crystals host significant populations of H2 (NVN-) defect complexes whose absorption band partially overlaps the excitation wavelength. By correlating spectroscopic data with nonlinear measurements and modeling the response using an effective two-level system, we show that the observed saturation cannot be attributed solely to NV centers but arises from the combined contribution of NV-related and H2 defects. For the highly doped sample, we determine an effective linear absorption coefficient of alpha0 = 6.52 cm-1 and a saturation intensity of Is = 40.0 GW/cm2. These findings highlight the critical role of the complex defect landscape in governing the nonlinear optical response of NV-doped diamond and underscore the necessity of accounting for ancillary defect species in the design of diamond-based nonlinear and
quantum photonic devices.
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All authors Wojciech Talik, Mariusz Mrózek, Adam M. Wojciechowski, Krzysztof Dzierżęga
Applied Physics
Cryogenic enhancement of phononic four-wave mixing in AlScN/SiC
A. K. Behera, B. Smith, X. Du et al. (+9 more)
Surface acoustic wave platforms based on piezoelectric thin-film
heterostructures provide sub-wavelength acoustic confinement, making them attractive for compact nonlinear phononic systems with applications including frequency conversion, parametric interactions, and nonlinear signal processing. Here, we investigate guided surface acoustic wave phononic four-wave mixing at gigahertz frequencies in an aluminum scandium nitride/4H-silicon carbide
heterostructure operated at both room temperature (295 K) and cryogenic temperature (4 K). The 500 nm thick aluminum scandium nitride film supports guided Rayleigh and Sezawa modes with distinct displacement and strain energy density distributions, allowing a direct comparison of mode-dependent nonlinear behavior within the same device. Continuous-wave four-wave mixing measurements reveal an enhancement in the extracted modal nonlinear coefficient at 4 K relative to 295 K for both modes. In addition, the Rayleigh mode exhibits a modal nonlinearity approximately two orders of magnitude larger than that of the Sezawa mode across both temperature regimes. These results demonstrate that phononic four-wave mixing is strongly influenced by temperature, mode confinement, and strain localization while establishing aluminum scandium nitride on silicon carbide
heterostructures as a promising platform for engineering enhanced nonlinear phononic interactions for future classical and
quantum acoustic on-chip signal processing systems.
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All authors A. K. Behera, B. Smith, X. Du, Y. Deng, M. Miller, N. Sagartz, M. Koppa, C. T. Harris, M. Lilly, R. H. Olsson III, M. Eichenfield, L. Hackett
Optics
Bridging Photon Statistics and Phase Transitions in Random Fiber Lasers
Yifei Qi, Runhao Li, Jie Li et al. (+6 more)
Complex systems exhibit rich
equilibrium states, yet the universal principles governing these systems remain unrevealed, motivating the search for novel experimental platforms. Random fiber
lasers (RFLs), which generate partially-coherent light-wave through feedback from Rayleigh scattering, provide a photonic realization of such systems. Here we report a comprehensive theoretical and experimental investigation of
photon statistics for RFLs based on classical second-order temporal correlation function \( g^{(2)}(\tau) \), revealing unique statistical properties and introduce a two-dimensional framework for controlling
photon statistics. Remarkably, we establish a unified landscape between
photon correlation, intensity statistics governed by Levy statistics, and phase transitions with replica
symmetry breaking. This multifaceted relationship, observed for the first time, bridges disordered photonics with statistical physics of complex system. Our results offer new pathways for engineering
laser emission with controllable
photon statistics, and more broadly, this work positions RFLs as a fertile land for exploring emergent behaviors in disordered systems.
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All authors Yifei Qi, Runhao Li, Jie Li, Taichao Wang, Wangyouyou Li, Ernesto P. Raposo, Anderson S. L. Gomes, Han Wu, Zinan Wang
Applied Physics
A C-band microwave rectifier without capacitors for microwave power transmission
Biao Zhang, Wan Jiang, Chengyang Yu et al. (+1 more)
A microwave rectifier at 5.8 GHz without any capacitors is presented, which owns a measured MW-to-DC conversion efficiency of 68.1%. A harmonic rejection filter and a DC pass filter, which replace lumped capacitors in conventional microwave rectifiers, are applied to suppressing the harmonics produced by an HSMS-286 Schottky diode during rectifying. At the fundamental frequency, a microstrip impedance
transformer which contains a shunt {\lambda}g/8 short-ended microstrip transmission line and two short series microstrip transmission lines are applied to compensating the imaginary impedance of the diode and matching the input impedance of the rectifier. The measured MW-to-DC conversion efficiency agrees well to the simulated results. The novel rectifier without any lumped passive elements may be applied for power transmission system at higher microwave frequencies.
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All authors Biao Zhang, Wan Jiang, Chengyang Yu, Changjun Liu
Plasma Physics
A Novel Numerical Algorithms Optimization Method with Machine Learning Frameworks: Application on Real-time Plasmas Equilibrium Reconstruction in EXL-50U Spherical Torus
G.H. Zheng, S.F. Liu, X. Gu et al. (+14 more)
This work proposes for the first time a novel optimization method for numerical
algorithms, which takes advantages of machine learning frameworks PyTorch and TensorRT, leveraging their modularity, low development threshold, and automatic tuning characteristics to achieve a real-time
plasmas reconstruction
algorithm called PTEFIT as an application in tokamak-based controlled fusion that combines performance, flexibility, and usability. The
algorithm has been deployed and routinely operated on the EXL-50U spherical tokamak, with an average inference time of only 0.268ms per time slice at $129\times 129$ resolution, and has successfully driven feedback control of the maximum radial position of
plasmas and isoflux control. We believe that its design philosophy has sufficient potential to accelerate development and optimization in GPU parallel computing, and is expected to be extended to other numerical
algorithms.
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All authors G.H. Zheng, S.F. Liu, X. Gu, Y.P. Zhang, J. Li, Y. Liu, X.C. Lun, L. Xing, J.G. Chen, Z.Y. Chen, Y. Yu, D. Guo, Z.Y. Yang, H.S. Xie, X.M. Song, Y.J. Shi, EXL-50U Team
Instrumentation and Detectors
Performance Test and Circuit Simulation for R12699-406-M4 Photomultiplier Tube Base
Houqi Huang, Peiyuan Chen, Ke Han et al. (+8 more)
The next-generation
liquid xenon experiments like PandaX-xT target an energy range from sub-keV to multi-MeV to address the requirement of multiple physics searches. The Hamamatsu R12699-406-M4 photomultiplier tubes (PMTs) were developed and selected as
photon sensors for PandaX-xT. Their voltage-divider base is optimized for a broad dynamic range, from single-photoelectron (SPE) sensitivity to 30~nC collected charge (matching the 2.5~MeV Q-value of $^{136}$Xe neutrinoless double beta decay~(NLDBD)). Using a dedicated test bench, we characterize the saturation and suppression responses of R12699-406-M4 PMTs with this base design. Based on measured PMT-base responses, we develop a
circuit simulation model that accurately reproduces the physical mechanisms underlying these effects with key parameters tuned via experimental data. The combined simulation and bench-test approach guides base design and optimization, enabling improved detector dynamic range and supporting future saturation and suppression correction studies in data analysis.
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All authors Houqi Huang, Peiyuan Chen, Ke Han, Yang Liu, Guanbo Wang, Shaobo Wang, Weihao Wu, Binbin Yan, Peihua Ye, Jiaxu Zhou, Zhizhen Zhou
General Physics
Some ways parameter calculation curvilinear uniformly accelerated motion
V. Voytik
The parameters of uniformly accelerated reference frame s three equivalent ways is calculated. The article also found explicitly transformation to uniformly accelerated reference frame and proved the assertion that Thomas precession and Wigner rotation s in opposite directions and cancel each other out.
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Instrumentation and Detectors · Cross-listed from cs.LG
Machine Learning-Based Framework for Real Time Detection and Early Prediction of Control Valve Stiction in Industrial Control Systems
Natthapong Promsricha, Chotirawee Chatpattanasiri, Nuttavut Kerdgongsup et al. (+1 more)
Control valve stiction, a friction that prevents smooth valve movement, is a common fault in industrial process systems that causes instability, equipment wear, and higher maintenance costs. Many plants still operate with conventional valves that lack real time monitoring, making early predictions challenging. This study presents a machine learning (ML) framework for detecting and predicting stiction using only routinely collected process signals: the controller output (OP) from control systems and the process variable (PV), such as flow rate. Three deep learning models were developed and compared: a Convolutional Neural Network (CNN), a hybrid CNN with a Support Vector Machine (CNN-SVM), and a Long Short-Term
Memory (LSTM) network. To train these models, a data-driven labeling method based on slope ratio analysis was applied to a real oil and gas refinery
dataset. The LSTM model achieved the highest accuracy and was able to predict stiction up to four hours in advance. To the best of the authors' knowledge, this is the first study to demonstrate ML based early prediction of control valve stiction from real industry data. The proposed framework can be integrated into existing control systems to support predictive maintenance, reduce downtime, and avoid unnecessary hardware replacement.
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All authors Natthapong Promsricha, Chotirawee Chatpattanasiri, Nuttavut Kerdgongsup, Stavroula Balabani
Physics and Society · Cross-listed from econ.GN
Economic complexity and regional development in India: Insights from a state-industry bipartite network
Joel M Thomas and Abhijit Chakraborty
This study investigates the economic complexity of Indian states by constructing a state-industry bipartite network using firm-level data on registered companies and their paid-up capital. We compute the Economic Complexity Index and apply the fitness-complexity
algorithm to quantify the diversity and sophistication of productive capabilities across the Indian states and two union territories. The results reveal substantial heterogeneity in regional capability structures, with states such as Maharashtra, Karnataka, and Delhi exhibiting consistently high complexity, while others remain concentrated in ubiquitous, low-value industries. The analysis also shows a strong positive relationship between complexity metrics and per-capita Gross State Domestic Product, underscoring the role of capability accumulation in shaping economic performance. Additionally, the number of active firms in India demonstrates a persistent exponential growth at an annual rate of 11.2%, reflecting ongoing formalization and industrial expansion. The ordered binary
matrix displays the characteristic triangular structure observed in complexity studies, validating the applicability of complexity frameworks at the sub-national level. This work highlights the usefulness of firm-based data for assessing regional productive structures and emphasizes the importance of capability-oriented strategies for fostering balanced and sustainable development across Indian states. By demonstrating the usefulness of firm registry data in data constrained environments, this study advances the empirical application of economic complexity methods and provides a quantitative foundation for capability-oriented industrial and regional policy in India.
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Optics
Optical Self-Trapping and Nonlinear Light-Matter Interactions in Biological Soft Matter
Lu Tian, Xianyang Liang, Liqin Tang et al. (+5 more)
Low-scattering, deep-penetration light transport in biological media remains a pivotal challenge for biophotonic technologies, including biomedical imaging, optical diagnostics, and photodynamic therapy. This review builds upon and extends our earlier studies of nonlinear optical self-trapping and optically induced waveguiding in biological suspensions, such as human erythrocytes and cyanobacteria, where light-matter coupling is governed by optical-force-mediated particle redistribution. Recent progress has revealed increasingly rich and complex regimes, including the propagation and nonlinear self-action of structured (
vortex) beams in biological environments, as well as nonlinear responses dominated by thermally driven mechanisms in absorptive biomolecular solutions (e.g., heme and chlorophyll). We place particular emphasis on distinctive nonlinear phenomena observed in these systems, including spatial self-phase modulation, optical-force-induced sculpturing of effective energy landscapes, and quasi-waveguide formation in soft, heterogeneous biological media. We conclude by highlighting emerging opportunities to harness these nonlinear behaviors for deep-tissue imaging, label-free biosensing, and the realization of biocompatible photonic structures and devices assembled directly from living or hybrid biological matter.
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All authors Lu Tian, Xianyang Liang, Liqin Tang, Rekha Gautam, Anna Bezryadina, Yu-Xuan Ren, Yi Liang, Zhigang Chen
Physics and Society
Logarithmic scaling and stochastic criticality in collective attention
Keisuke Okamura
We uncover a universal scaling law governing the dispersion of collective
attention and identify its underlying
stochastic criticality. By analysing large-scale ensembles of Wikipedia page views, we find that the variance of logarithmic
attention grows ultraslowly, $\operatorname{Var}[\ln{X(t)}]\propto\ln{t}$, in sharp contrast to the power-law scaling typically expected for diffusive processes. We show that this behaviour is captured by a minimal
stochastic differential equation driven by fractional Brownian motion, in which long-range
memory ($H$) and temporal decay of
volatility ($\eta$) enter through the single exponent $\xi\equiv H-\eta$. At marginality, $\xi=0$, the variance grows logarithmically, marking the critical boundary between power-law growth ($\xi>0$) and saturation ($\xi<0$). By incorporating article-level heterogeneity through a Gaussian mixture model, we further reconstruct the empirical distribution of cumulative
attention within the same framework. Our results place collective
attention in a distinct class of non-Markovian
stochastic processes, with close affinity to ageing-like and ultraslow dynamics in glassy systems.
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Optics · Cross-listed from quant-ph
Hierarchy of quantum correlations in qubit-qutrit axially symmetric states
Venkat Abhignan and R. Muthuganesan
We investigate
quantum correlations in a hybrid
qubit-qutrit system subject to both axial and planar single-ion anisotropies, dipolar
spin-
spin interactions, and Dzyaloshinskii-Moriya (DM) coupling. Using Negativity, Measurement-Induced Non-locality (MIN), Uncertainty-Induced Nonlocality (UIN), and Bell nonlocality (as quantified by the CHSH inequality) as measures, we analyze the interplay between anisotropy parameters,
magnetic fields, and temperature on the survival of
quantum correlations. Our results demonstrate that Bell nonlocality and
entanglement (Negativity) are highly sensitive to temperature and anisotropy, exhibiting sudden death under thermal noise, whereas MIN and UIN are significantly more robust. In particular, these discord-like and information-theoretic measures provide the largest baseline and persist even in parameter regions where
entanglement vanishes, highlighting their suitability as a quantumness witness in realistic conditions. Notably, our Bell nonlocality study is tailored to the asymmetric
qubit-qutrit setting by exploiting a recently developed
qubit-qudit CHSH maximization framework. However, Bell nonlocality is confirmed to be the most fragile, surviving only in narrow parameter windows at low temperature. A key finding of this work is that we observe the fragility hierarchy: Bell nonlocality $\subseteq$ Negativity $\subseteq$ UIN(MIN) in the
qubit-qutrit setting. These results provide deeper insight into the relative robustness of distinct
quantum resources in anisotropic
qubit-qutrit models, suggesting that
quantum discord-like measures, such as MIN and UIN, may serve as more practical resources than
entanglement for
quantum information tasks in thermally active
spin systems.
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