Computational Physics · Cross-listed from gr-qc
APRIL: Auxiliary Physically-Redundant Information in Loss – A physics-informed framework for parameter estimation with a gravitational-wave case study
Matteo Scialpi, Francesco Di Clemente, Leigh Smith et al. (+1 more)
Physics-Informed Neural Networks (PINNs) embed the partial differential equations (PDEs) governing the system under study directly into the training of Neural Networks, ensuring solutions that respect physical laws. While effective for single-system problems, standard PINNs scale poorly to
datasets containing many realizations of the same underlying physics with varying parameters. To address this limitation, we present a complementary approach by including auxiliary physically-redundant information in loss (APRIL), i.e. augment the standard supervised output-target loss with auxiliary terms which exploit exact physical redundancy relations among outputs. We mathematically demonstrate that these terms preserve the true physical minimum while reshaping the loss landscape, improving convergence toward physically consistent solutions. As a proof-of-concept, we
benchmark APRIL on a fully-connected neural network for gravitational wave (GW) parameter estimation (PE). We use simulated, noise-free compact binary coalescence (CBC) signals, focusing on inspiral-frequency waveforms to recover the chirp mass $\mathcal{M}$, the total mass $M_\mathrm{tot}$, and symmetric mass ratio $\eta$ of the binary. In this controlled setting, we show that APRIL achieves up to an order-of-magnitude improvement in test accuracy, especially for parameters that are otherwise difficult to learn. This method provides physically consistent learning for large multi-system
datasets and is well suited for future GW analyses involving realistic noise and broader parameter ranges.
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All authors Matteo Scialpi, Francesco Di Clemente, Leigh Smith, Michał Bejger
Atomic Physics · Cross-listed from quant-ph
Robust Superradiance and Spontaneous Spin Ordering in Disordered Waveguide Quantum Electrodynamics
Xin H. H. Zhang, Daniel Malz and Peter Rabl
We study the collective emission of a disordered array of $N$ excited two-level atoms into a one-dimensional photonic waveguide. In the perfectly ordered case, where atoms are spaced by exact integer multiples of the wavelength, the system exhibits the characteristic superradiant burst with a peak emission rate scaling as $N^2$. Using large-scale semiclassical simulations, we find that this key signature of superradiance remains asymptotically robust under strong spatial and spectral disorder, but also exhibits subtle finite-size scaling toward this limit. To explain our observations, we provide an analytical variational estimate for the maximal decay rate, which tightly bounds the numerical results and reveals how disorder shapes the collective decay. Specifically, we find that even in the presence of strong disorder, the
spins tend to self-organize spontaneously according to their locations, which overall optimizes constructive interference effects and explains the emergence of mirror-asymmetric correlations in superradiant decay. These findings resolve important open questions regarding the existence and nature of superradiance in strongly disordered arrays and offer valuable insights for understanding collective
quantum optical phenomena in realistic systems.
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Medical Physics
Spherical Radiomics – A Novel Approach to Glioblastoma Radiogenomic Analysis of Heterogeneity
Haotian Feng and Ke Sheng
We develop and validate a novel spherical radiomics framework for predicting key molecular biomarkers using multiparametric MRI. Conventional Cartesian radiomics extract tumor features on orthogonal grids, which do not fully capture the tumor's radial growth patterns and can be insensitive to evolving molecular signatures. In this study, we analyzed GBM radiomic features on concentric 2D shells, which were then mapped onto 2D planes for radiomics analysis. Radiomic features were extracted using PyRadiomics from four different regions in GBM. Feature selection was performed using ANOVA F-statistics. Classification was conducted with multiple machine-learning models. Model interpretability was evaluated through SHAP analysis, clustering analysis, feature significance profiling, and comparison between radiomic patterns and underlying biological processes. Spherical radiomics consistently outperformed conventional 2D and 3D Cartesian radiomics across all prediction tasks. The best framework reached an AUC of 0.85 for MGMT, 0.80 for EGFR, 0.80 for PTEN, and 0.83 for survival prediction. GLCM-derived features were identified as the most informative predictors. Radial transition analysis using the Mann-Whitney U-test demonstrates that transition slopes between T1-weighted contrast-enhancing and T2/FLAIR hyperintense lesion regions, as well as between T2 intense lesion and a 2 cm peritumoral expansion region, are significantly associated with biomarker status. Furthermore, the observed radiomic changes along the radial direction closely reflected known biological characteristics. Radiomic features extracted on the spherical surfaces at varying radial distances to the GBM tumor centroid are better correlated with important tumor molecular markers and patient survival than the conventional Cartesian analysis.
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Optics
Coherent absorption reveals colors hidden in a grey Fabry-Pérot cavity
Giuseppe E. Lio, Giulio Carotta, Lorenzo Lavista et al. (+8 more)
Thin dielectric films are known to show distinct colors, responsible for the iridescence of various natural and artificial objects such as insect wings and soap bubbles. In the present article we show that a specialized thin film Fabry-Pérot resonator, that we name conductor-dielectric-conductor (CDC) matched cavity, appears instead completely grey when observed under ordinary conditions (i.e. by analyzing the transmitted or reflected incoherent white light). Nonetheless, the matched CDC cavity still retains spectral information, that clearly appear when the cavity is analyzed by the coherent absorption technique. The CDC system is simply a dielectric thin film sandwiched by two conducting interfaces, whose conductivity shall be appropriately matched depending upon the dielectric refractive index. In practical applications, the ideal conducting interfaces can be safely replaced by thin metal films, making the system easily applicable in particular for cryptographic purposes. We indeed demonstrated experimentally that a visually recognizable thin-film color pattern can be concealed to an ordinary observer, and finally recovered through a dedicated coherent absorption decoding apparatus.
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All authors Giuseppe E. Lio, Giulio Carotta, Lorenzo Lavista, Andrea Camposeo, Giacomo Venturi, Agnese Guernieri, Alessandro Pitanti, Simon A. R. Horsley, Giuseppe C. La Rocca, Alessandro Tredicucci, Simone Zanotto
Chemical Physics
Isomer effects on neutral-loss dissociation channels of nitrogen-substituted PAH dications
Sumit Srivastav, Sylvain Maclot, Alicja Domaracka et al. (+2 more)
We investigate two nitrogen-containing isomers of polycyclic aromatic hydrocarbons (PAHs), quinoline (Q) and isoquinoline (IQ), of composition C$_9$H$_7$N in collisions with 7~keV O$^+$ and 48~keV O$^{6+}$ projectile ions. Employing ion-ion coincidence mass spectrometry, we determine branching ratios for H-loss, C$_2$H$_2$-loss, and HCN-loss dissociation channels of Q$^{2+}$ and IQ$^{2+}$. The overall contribution of HCN-loss is found to be the dominant decay channel. A comparison with the results of a parallel experiment on naphthalene, the simplest PAH, reveals that HCN-loss in both isomers has a higher propensity than the analogous C$_2$H$_2$-loss of naphthalene. The positional identity of the nitrogen atom in the two isomers mainly manifests in many-body fragmentation of their dications. Potential energy surfaces of Q$^{2+}$ and IQ$^{2+}$ are further computed to explore complete fragmentation mechanisms. Parent dications (Q$^{2+}$ and IQ$^{2+}$) are identified to isomerize via seven-membered ring structures prior to elimination of C$_2$H$_2$ and HCN. While
prompt dissociation is the primary pathway, the dominant channel of each neutral-loss class also exhibits delayed fragmentation.
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All authors Sumit Srivastav, Sylvain Maclot, Alicja Domaracka, Sergio Díaz-Tendero, Patrick Rousseau
Optics
Coupled electric dipole model for a Su-Schrieffer-Heeger chain of optically resonant coreshell nanoparticles
Álvaro Buendía and Nuno M.R. Peres
Coreshell nanoparticles can combine optical features of different materials in a single nanostructure, which makes them interesting for many applications from biomedicine to energy harvesting. On the other hand, periodic arrays of plasmonic nanoparticles can exhibit topological phenomena such as topological edge states. Here we study periodic chains of Si@Ag coreshell nanoparticles. For this task, we combine the hybridization of surface plasmonic modes in complex nanostructures with the coupled electric dipole formalism employed for modelling the scattering of light by periodic arrays of small plasmonic nanoparticles. We propose treating coreshell nanoparticle as several coupled electric dipoles instead of just one and show how this is a more appropriate framework to study arrays of coreshell nanoparticles, which allows to build a one-to-one connection between the resonant modes of the nanoparticles and the dispersion bands of the system. Within this formalism, we show that a Su-Schrieffer-Heeger (SSH) chain of coreshell Si@Ag nanoparticles host multiple topological edge states pinned at the resonant frequencies of the coreshell nanoparticles.
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Optics
Electronic-Photonic Interface for Multiuser Optical Wireless Communication
Youngin Kim, Laurenz Kulmer, Jae-Yong Kim et al. (+3 more)
We demonstrate an electronic-photonic (EP) interface for multiuser optical wireless communication (OWC), consisting of a multibeam optical phased array (MBOPA) along with co-integrated electro-optic (EO) modulators and high-speed CMOS drivers. The MBOPA leverages a path-length difference in the optical phased array (OPA) along with wavelength-division multiplexing technology for spatial carrier aggregation and multiplexing. To generate two and four pulsed amplitude modulation signals, and transmit them to multiple users, we employ an optical digital-to-analog converter technique by using two traveling-wave electrode Mach-Zehnder modulators, which are monolithically integrated with high-speed, wide-output-swing CMOS drivers. The MBOPA and monolithic EO modulator are implemented by silica wafer through planar lightwave
circuit fabrication process and a 45-nm monolithic silicon photonics technology, respectively. We measured and analyzed two-channel parallel communication at a data rate of 54 Gbps per user over the wireless distance of 1 m. To the best of our knowledge, this is the first system level demonstration of the multi-user OWC using the in-house-designed photonic and monolithically integrated chips. Finally, we suggest best modulation format for different data rate and the number of multibeams, considering effects of the proposed OPA and the monolithic modulator.
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All authors Youngin Kim, Laurenz Kulmer, Jae-Yong Kim, Hamza Kurt, Juerg Leuthold, Hua Wang
Computational Physics
Multiphysics Finite Element Modeling of Irradiation and Thermal Behavior Demonstrated on a Fuel-Assembly Problem
Fabrizio Aguzzi, Martín Armoa, Santiago M. Rabazzi et al. (+2 more)
This work presents a modeling framework to represent the thermomechanical behavior of complex materials based on micromechanical dynamics. The framework is applied to
nuclear fuel rod elements composed of Zircaloy-2 cladding tubes and spacer grids under typical Pressurized Water Reactor (PWR) conditions. Thermal expansion and thermal creep are incorporated through a VPSC-FEM coupling with the finite element solver Code_Aster, enabling analysis of in-reactor behavior under combined thermal, mechanical, and irradiation loading. The model captures anisotropic deformation driven by crystallographic texture and prismatic slip activity under radial loading. Thermal creep, being stress-sensitive, contributes to early-stage stress relaxation and strain accumulation, leading to higher strain compared to the irradiation-only case. The interaction of thermal creep with irradiation mechanisms modifies the stress distribution and clearance
evolution, with relaxation governed by prismatic slip. For fuel rod components, irradiation-induced mechanisms dominate the long-term clearance behavior, whereas thermal effects remain relevant in contact dynamics during thermal preloading. The stress-strain response is found to be more sensitive to micromechanical processes than to elastic constants. This high-resolution formulation enables predictive modeling of spacer-cladding interaction and provides a foundation for developing reduced-order models.
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All authors Fabrizio Aguzzi, Martín Armoa, Santiago M. Rabazzi, César Pairetti, Alejandro Albanesi
Computational Physics
Rippled Moire Superlattices for Decoupled Ferroelectric Bits
Di Fan, Changming Ke and Shi Liu
Symmetry considerations suggest that moire superlattices formed by twisted two-dimensional materials should preserve overall inversion
symmetry. However, experiments consistently report robust ferroelectricity in systems such as twisted
bilayer h-BN, posing a fundamental discrepancy between theory and experiment regarding its microscopic origin. Here, using large-scale finite-field molecular dynamics simulations, we challenge the prevailing defect-pinning hypothesis and instead identify an out-of-plane bending field, induced by in-plane compressive strain, as the key
symmetry-breaking mechanism. This strain-induced rippling drives spatially heterogeneous interlayer sliding and distorts the moire domain wall network, resulting in a four-state ferroelectric system. Remarkably, we show this mechanism can be harnessed at the nanoscale, where localized nanobubbles designate the moire
lattice's fundamental hexagonal domain clusters as the smallest individually addressable ferroelectric bits, thereby imposing local control on an otherwise globally defined structure. Our findings establish a geometry-driven framework for understanding and engineering moire ferroelectrics, offering not only a route toward ultra-high-density, rewritable
memory, but also a strategy for locally tuning the moire potential itself, a critical step for manipulating emergent correlated and topological
quantum phases.
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Medical Physics
An efficient approach with theoretical guarantees to simultaneously reconstruct activity and attenuation sinogram for TOF-PET
Liyang Hu and Chong Chen
In positron emission
tomography (PET), it is indispensable to perform attenuation correction in order to obtain the quantitatively accurate activity map (tracer distribution) in the body. Generally, this is carried out based on the estimated attenuation map obtained from computed
tomography or
magnetic resonance imaging. However, except for errors in the attenuation correction factors obtained, the additional scan not only brings in new radiation doses and/or increases the scanning time but also leads to severe misalignment induced by various motions during and between the two sequential scans. To address these issues, based on maximum likelihood estimation, we propose a new mathematical model for simultaneously reconstructing the activity and attenuation sinogram from the time-of-flight (TOF)-PET emission data only. Particularly, we make full use of the exclusively exponential form for the attenuation correction factors, and consider the constraint of a total amount of the activity in some mask region in the proposed model. Furthermore, we prove its well-posedness, including the existence, uniqueness and stability of the solution. We propose an alternating update
algorithm to solve the model, and also analyze its convergence. Finally, numerical experiments with various TOF-PET emission data demonstrate that the proposed method is of numerical convergence and robust to noise, and outperforms some state-of-the-art methods in terms of accuracy and efficiency, and has the capability of autonomous attenuation correction.
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Optics · Cross-listed from quant-ph
Exact dynamics and qubit inversion of non-Hermitian driven two-level systems
Ivan A. Bocanegra-Garay and Luis M. Nieto
The supersymmetric structure of a generalized non-Hermitian driven two-level system is demonstrated. A
unitary rotation turns the
Hamiltonian into a more convenient form. After decoupling a set of differential equations, the supersymmetric structure of the problem can be unequivocally ap- appreciated. Performing a spectral analysis of an auxiliary stationary Schrödinger-like equation, complex time-dependent driving functions are obtained for which the corresponding (time-dependent) Schrödinger equation can be straightforwardly solved. Such complex drivings are seen to produce transitions in the
qubit state in different, however interesting, manners. We believe that the results reported here will be of interest for designing and carrying out various experiments in laboratories specializing in
nuclear magnetic resonance or in optics with gain and loss materials.
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Chemical Physics · Cross-listed from cond-mat.mtrl-sci
Ultrafast exciton polaron dynamics in 2D Ruddlesden Popper lead halide perovskites
Anirban Mondal, Kwang Jin Lee, Seungmin Lee et al. (+5 more)
Two dimensional Ruddlesden Popper (2D) RP hybrid perovskites exhibit substantially higher chemical and structural stability than their three dimensional (3D) counterparts, positioning them as promising candidates for next generation optoelectronics. While quasiparticle dynamics in 3D perovskites are well studied, their 2D analogues remain comparatively underexplored. Here we systematically investigate the branching, dynamics, and interactions of free
excitons (FEs) and
exciton polarons EPs in monolayer 2D RP perovskites using visible range femtosecond transient absorption TA spectroscopy. We prepared monolayer 2D RP perovskite thin films with varied organic spacers and distinct fabrication routes for comparative analysis. We find that the EP binding energy is 50 65 meV in (BA)2PbI4 and 37 39 meV in (PEA)2PbI4, consistent with spacer layer dependent coupling as corroborated by FTIR. We reveal a dynamic
equilibrium between FEs and EPs that persists for tens of picoseconds. Notably, the TA signatures differ by fabrication route films from the newly developed process show weaker Auger annihilation and a reduced hot
phonon bottleneck than those from the conventional route trends consistent with fewer traps and
impurities in the former. Coupled rate equation modeling reproduces the transients and quantifies the processes of hot carrier relaxation,
exciton exciton annihilation,
exciton phonon coupling, and FE EP interconversion. These results demonstrate that the chemical synthetic process (fabrication route) and spacer choice significantly influence EP stability and population balance, offering practical levers for engineering ultrafast photophysics in 2D perovskites and guiding the design of advanced optoelectronic devices.
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All authors Anirban Mondal, Kwang Jin Lee, Seungmin Lee, Oui Jin Oh, Myeongsam Jen, Jun Hong Noh, Jong Min Lim, Minhaeng Cho
Chemical Physics · Cross-listed from cond-mat.mtrl-sci
Unraveling the Corrosion Mechanism of Boro-Alumino-Phospho-Silicate Glass: Advanced Insights from Solid-State NMR Spectroscopy
Muhammad Amer Khan, Lili Hu, Shubin Chen et al. (+2 more)
Corrosion mechanism of minerals and glass is a critical study domain in geology and materials science, vital for comprehending material durability under various environmental conditions. Despite decades of extensive study, a core aspect of these mechanisms - specifically, the formation of amorphous alteration layers upon exposure to aqueous environments - remains controversial. In this study, the corrosion behavior of a boro-alumino-phospho-silicate glass (BAPS) was investigated using advanced solid-state
nuclear magnetic resonance (SSNMR) and SEM techniques. The results reveal a uniform nanoscale phase separation into Al-P-rich and Al-Si-rich domains. During corrosion, the Al-P-rich domain undergoes gelation, whereas the Al-Si-rich domain remains vitreous, forming a gel layer comprised of both phases. Although SEM images show a sharp gel/glass interface - suggestive of a dissolution-precipitation mechanism - the phase coexistence within the gel layer provides definitive evidence against such a mechanism. Instead, we propose an in situ transformation mechanism governed by chemical reactions, involving: (i) preferential hydrolysis of Al-P-rich domain leading to porous gel regions; (ii) retention of Al-Si glass domains within the gel layer, with water infiltrating inter-network spaces; and (iii) selective leaching of phosphorus over aluminum, leading to reorganization of the gel network.
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All authors Muhammad Amer Khan, Lili Hu, Shubin Chen, Yongchun Xu, Jinjun Ren
Optics
A Semiconductor Photon Bose-Einstein Condensate as a Practical Light Source for Ranging Finding
Ross C. Schofield, Daniel Lim, Nathan R. Gemmell et al. (+5 more)
Here we report the measurement of thermal
photon statistics from a
semiconductor photon Bose-Einstein condensate operating just above the condensation threshold. We identify a regime where coherent, single mode emission occurs while still demonstrating significant
photon bunching. Taking advantage of the
photon bunching, along with the continuous-wave operation and high
photon flux, we demonstrate optical range sensing using a
photon Bose-Einstein condensate. We characterise the precision of the range measurement and analyse the dependence on the condensate's pump power and resulting coherence properties.
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All authors Ross C. Schofield, Daniel Lim, Nathan R. Gemmell, Edmund Clarke, Ian Farrer, Aristotelis Trapalis, Jon Heffernan, Rupert F. Oulton
Plasma Physics
Narrow Operator Models of Stellarator Equilibria in Fourier Zernike Basis
Timo Thun, Rory Conlin, Dario Panici et al. (+1 more)
Numerical computation of the ideal Magnetohydrodynamic (MHD)
equilibrium magnetic field is at the base of stellarator optimisation and provides the starting point for solving more sophisticated Partial Differential Equations (PDEs) like transport or
turbulence models. Conventional approaches solve for a single stationary point of the ideal MHD equations, which is fully defined by three invariants and the numerical scheme employed by the solver. We present the first numerical approach that can solve for a continuous distribution of
equilibria with fixed boundary and rotational transform, varying only the pressure invariant. This approach minimises the force residual by optimising parameters of multilayer perceptrons (MLP) that map from a scalar pressure multiplier to the
Fourier Zernike basis as implemented in the modern stellarator
equilibrium solver DESC.
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All authors Timo Thun, Rory Conlin, Dario Panici, Daniel Böckenhoff
Optics
Unveiling spin-orbital angular momentum locking in photonic Dirac vortex cavities
Haitao Li, Jiusi Yu, Jiayu Fan et al. (+6 more)
Dirac
vortices, originally studied in
quantum field theories to predict localized zero-energy modes, were recently realized in photonics, leading to Dirac
vortex cavities. With topological protection, Dirac
vortex cavities offer robust single-mode large-area localized modes appealing for high-performance micro-
lasers and other applications. As a spectrally-isolated single mode, the radiation of a Dirac
vortex cavity mode was believed as having vanishing orbital angular momentum due to time-reversal
symmetry. Here, we report the direct observation of orbital angular momentum radiation of a Dirac
vortex cavity through
spin-resolved measurements. Remarkably, we confirm the
spin-orbital angular momentum locking in such radiation due to the
spin-valley locking and inter-valley couplings. We demonstrate that the
spin-orbital angular momentum locking is controlled by the chirality of the Kekulé modulation and propose design schemes for arbitrary-order single-mode OAM radiation.
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All authors Haitao Li, Jiusi Yu, Jiayu Fan, Shijie Kang, Bo Hou, Zhi-Kang Lin, Hanchuan Chen, Jian-Hua Jiang, Xiaoxiao Wu
Computational Physics · Cross-listed from astro-ph.IM
Design of an Imaging Air Cherenkov Telescope array layout with differential programming
Cyril Alispach, Matthieu Heller and Teresa Montaruli
Current optimization of ground-based Cherenkov
telescopes arrays, also called Imaging Air Cherenkov
Telescope (IACT) arrays, relies on brute-force human-driven approaches based on large simulations requiring both high amount of storage and long computation time. To explore the full phase space of
telescope positioning of a given array even more simulations would be required. To optimize any array layout, we explore the possibility of developing a differential program with surrogate models of IACT arrays based on high-level instrument response functions (IRFs). The simulation time of a single
telescope to a
cosmic-ray event can be significantly reduced with its instrument response function or with generative models. However, it is not straight forward to model the array of
telescopes from a set of single
telescope surrogate models as the array is a stereoscopic imaging system. The complexity increases as well if the
telescopes in the array are of different types. Additionally, the optimum of the array layout depends on the scientific use case. Current array layout optimization are obtained by minimizing the sensitivity of the array, a metric that depends on several high-level parameters such as the trigger efficiency, the energy and angular resolution, as well as the background rejection capability. The variety of
telescopes types in IACT arrays, such as in the Cherenkov
Telescope Array Observatory (CTAO), not only extends the sensitive energy range but also allows for cross-calibration of the instruments. Therefore, the optimal array layout is not only which minimizes sensitivity but also which reduces the systematic uncertainties. We focus on the optimization of a
telescope array based on the SST-1M IACTs in Hanle, Ladakh India aiming at building a generic optimization pipeline for future ground-based
cosmic-ray observatories
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Accelerator Physics
Attosecond Waveform Synthesis through Echo-enabled Harmonic Generation Free-electron Lasers
Lanpeng Ni, Junhao Liu, Zheng Qi et al. (+1 more)
Attosecond pulse trains (APTs) are indispensable for probing electron dynamics at their intrinsic timescales. High harmonic generation (HHG) has long been a successful and widely used technique in producing extreme ultraviolet APTs. While in the soft X-ray regime, HHG suffers from low conversion efficiency and lacking flexibility in the waveform and spectrum control. Here in this study, based on the waveform synthesis of the echo-enabled harmonic generation (EEHG) free-electron
laser (FEL), we propose a novel method that can generate soft X-ray APTs with high temporal and spectral tunability. EEHG scheme is well-known in forming phase-locked high harmonic bunching combs down to the soft X-ray regime. And We can facilitate successive FEL lasing in several different harmonic numbers and then perform the coherent waveform synthesis to generate soft X-ray APTs. Three-dimensional simulation results indicate that reproducible generation of coherent APTs in the soft X-ray regime with peak power of 3.5 GW and micropulse duration of 160 as can be achieved by five-harmonic synthesis. And the micropulse duration together with the spectral components of the APTs can be adjusted easily according to the programmable high harmonic bunching combs in the EEHG scheme. This method has the potential to establish a robust platform for attosecond sciences in the soft X-ray regime, which can enable unprecedented studies of electron dynamics in physical and chemical reactions, biological systems and
quantum materials.
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All authors Lanpeng Ni, Junhao Liu, Zheng Qi, Chao Feng
Accelerator Physics · Cross-listed from astro-ph.IM
A New Method for Aperture Masking Interferometric Imaging: Demonstration with the JWST
Christopher Carilli, Bojan Nikolic, Laura Torino et al. (+2 more)
We present a new method for aperture masking interferometric (AMI) imaging at near-IR wavelengths using
radio astronomical techniques. The method starts with derivation of interferometric visibilities from a
Fourier transform of the interferograms. An iterative joint optimization process is then employed, using self-calibration of the interferometric element-based complex voltage gains (i.e. electric fields), and CLEAN deconvolution to obtain the source structure. We demonstrate the efficacy of the method using the NIRISS aperture masking interferometer on the James Webb Space
Telescope (JWST) at 4.8~$\mu$m and 3.8~$\mu$m. Due to a number of effects (the large pixel size, charge migration, near-field optics), the method also requires an initial visibility-based amplitude normalization using observations of a well know point-source calibration
star. We employ early science observations of the dusty binary Wolf-Rayet
star WR137. Images with a dynamic range (peak/rms) of $\sim 240$ on the target, and $\sim 1000$ on the calibrator, are synthesized from a short integration. The self-calibration process determines the
photon path-lengths through the optical system to each aperture using data on the target source itself, thereby representing an essentially 'real-time', precise wavefront error sensor. Four independent measures of the JWST mirror segment pistons (two wavelengths for two sources), agree to within 10~nm to 15~nm, comparable to the expected errors based on an analysis of closure phases on the calibrator
star. Including a baseline-based phase correction improves the dynamic range of the final images by about 23%.
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All authors Christopher Carilli, Bojan Nikolic, Laura Torino, N. Thyagarajan, Ubaldo Iriso
Applied Physics
Molecularly imprinted nanopores for multiplexed sensing, release, and in-edge computing
Ali Douaki, Shukun Weng, Silvia Dante et al. (+4 more)
In nanopore technology, the development of multiplexed detection and release platforms with high spatial and temporal resolution remains a significant challenge due to the difficulty in distinguishing signals originating from different nanopores in a single chip. In this work, we present a solid-state nanopore system functionalized with molecularly imprinted
polymers (MIPs) for the selective detection and controlled release of neurotransmitters. We designed a nanopore array where each nanopore is functionalized with a specific MIP able to recognize specific neurotransmitters (dopamine, gamma-aminobutyric acid, and histamine, respectively). The platform demonstrated high performance in terms of sensitivity, selectivity, recovery, and stability. Multiplexed detection with high spatiotemporal resolution of the order of 100 ms/ 3 {\mu}m was achieved by specifically depositing MIPs and conductive hydrogels on different nanopores prepared on a single solid-state membrane. The employment of micro-chambers for each nanopore prevented signal cross-talk, thereby enabling simultaneous detection and release of multiple neurotransmitters. Moreover, we demonstrated computing with different logic gates and in-edge computing. This nanopore platform represents a radically novel approach towards hybrid solid-state nanopores able to perform real-time label-free multiplex detection, controlled biomolecule release, and ionic logic computing, addressing key challenges in neurochemical sensing and bio-computation.
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All authors Ali Douaki, Shukun Weng, Silvia Dante, Nako Nakatsuka, Makusu Tsutsui, Roman Krahne, Denis Garoli
Accelerator Physics
Low-impedance stripline kicker for the transverse instability suppression system of the synchrotron radiation facility "SKIF" light source
M. A. Baistrukov, E. A. Bekhtenev, A. A. Krasnov et al. (+2 more)
Construction of the new fourth generation synchrotron radiation facility (SRF) "SKIF" near Novosibirsk is nearing completion. "SKIF" uniqueness is ultra-low 75 pm natural emittance at 400 mA beam current and 3 GeV beam energy. Collective effects (beam interaction with the
vacuum chamber) are the main obstacles of achieving such emittance and beam current. To suppress these effects the storage ring will be equipped with a bunch-by-bunch feedback system. Important components of the feedback system are a stripline (fast) kicker and a beam position monitor. The paper describes design of the low-impedance stripline kicker for SRF "SKIF" storage ring, optimized for the manufacturing and for the uniformity of the imparted transverse kick. The kicker qualities such as S-parameters, imparted transverse momentum, transfer and beam impedances are presented. The chosen length of the stripline kicker allows its use as a beam position monitor.
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All authors M. A. Baistrukov, E. A. Bekhtenev, A. A. Krasnov, D. A. Nikiforov, P. A. Piminov
Optics
A Quantitative Holographic Agglutination Assay for Immunoglobulin A
Rushna Quddus, Kent Kirshenbaum and David G. Grier
This study introduces a
Holographic Agglutination Assay for quantifying levels of the immunoglobulin
protein IgA in biological samples. This is the first example of a label-free and bead-free assay that quantifies
protein agglutinates by direct detection using Total
Holographic Characterization. A proof-of-concept assay for human serum immunoglobulins is demonstrated using Jacalin, the galactose-specific plant lectin, to induce selective agglutination. By analyzing the size, refractive index, and number of particles in an assay sample, we obtain a reproducible and quantitative measurement of galactosylated immunoglobulins in a given sample. The assay is calibrated for a physiologically relevant reference interval of IgA concentrations in a 10x diluted emulated biological sample from low (80 mg/dL, 5 {\mu}M) to high (320 mg/dL, 20 {\mu}M) levels. The assay clearly distinguishes samples containing IgA from samples containing IgG. More broadly, this study introduces a platform for creating lectin-mediated
Holographic Agglutination Assays to monitor levels of immunoglobulins in biological samples. The ability to quantify immunoglobulin levels efficiently in clinical samples is likely to be valuable for diagnostics and will provide a basis for assaying other
proteins that can be induced to agglutinate.
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Optics
High-bandwidth photodetector enabled by frequency-domain equalization
Wenxin Deng, Hengsong Yue, Xiaoyan Liu et al. (+4 more)
High-bandwidth germanium (Ge) photodetectors are crucial for silicon photonic integrated
circuits. However, their bandwidth is restricted by carrier transit time and parasitic parameters. In this work, we propose an equalization photodetector (EqPD) utilizing the frequency response of a high-bandwidth photodetector PDA to subtract the frequency response of a low-bandwidth photodetector PDB. With the response of PDB attenuating more severely than PDA at high frequency, the differential frequency response (the response of EqPD) can get higher values at high frequency than at low frequency, flattening the overall frequency response and expanding the bandwidth. Experimental results show that the EqPD has a bandwidth exceeding 110 GHz with a responsivity of 94 mA/W. A 100 Gbaud non-return-to-zero (NRZ) operation without digital signal processing is also demonstrated. To the best of our knowledge, this represents the highest bandwidth in a vertical Ge photodetector, providing a promising solution for high-speed photodetection in next-generation optical communication.
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All authors Wenxin Deng, Hengsong Yue, Xiaoyan Liu, Jianhong Liang, Jianbin Fu, Shilong Pan, Tao Chu
Fluid Dynamics
Nonhomogeneous elastic turbulence in the two-dimensional Taylor-Couette flow
Zhongxuan Hou, Stefano Berti, Teodor Burghelea et al. (+1 more)
Elastic
turbulence is a spatially and temporally disordered flow state appearing in viscoelastic fluids at vanishing fluid inertia and large elasticity. The resulting flows have broad technological interest, particularly to enhance mixing and heat transfer in microdevices. Although its experimental characterization is now well established in different setups, its theoretical understanding and numerical reproducibility remain challenging, especially in wall-bounded geometries. By means of numerical simulations, we investigate the onset of elastic
turbulence and the characteristics of the developed turbulent-like states in the two-dimensional, confined, Taylor-Couette system. First, we characterize the purely elastic instability, addressing previously contrasting evidences. We then show that the fully nonlinear dynamics are weakly anisotropic and strongly nonhomogeneous. Indeed, they are confined in a dynamically active region adjacent to the inner wall, akin to the elastic boundary layer from previous predictions. Within this region,in spite of some non-negligible deviations due to the nonhomeogeneity of our setup, the statistical and spectral turbulent properties are to reasonable extent not far from the theoretical expectations and experimental observations.
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All authors Zhongxuan Hou, Stefano Berti, Teodor Burghelea, Francesco Romanò
Applied Physics
A multiscale model of friction considering the influence of third-body wear particles
Parissa Sadat Alavi, Guillaume Anciaux, Jean-François Molinari et al. (+2 more)
Accurately predicting friction in sliding interfaces that contain third body wear particles is critical for engineering applications such as sliding movement in pistons, bearings, or metal forming. We present a hierarchical multiscale framework that links particle scale mechanics to macroscopic friction in a strip draw friction test. At the macroscale, a one dimensional finite element model reproduces the global stress state of the strip draw setup and updates the local wear particle density via Archard's law. The local friction force at each node is then computed from mesoscale simulation results. At the mesoscale, a coupled discrete element boundary element approach resolves load sharing between rough surfaces and rigid oblate spheroidal wear particles. The mesoscale solution returns to the macroscale solver a friction coefficient that depends on normal pressure, sliding velocity, surface geometry, and particle density, thereby closing the loop between scales. The simulated friction coefficient matches strip draw experiments, capturing both the observed decrease in friction with increasing normal pressure and the influence of tool pad size.
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All authors Parissa Sadat Alavi, Guillaume Anciaux, Jean-François Molinari, Loris Rocchi, Christian Leppin
Computational Physics
GO-Diff: Data-free and amortized global structure optimization
Nikolaj Rønne, Tejs Vegge and Arghya Bhowmik
We introduce GO-Diff, a
diffusion-based method for global structure optimization that learns to directly sample low-energy atomic configurations without requiring prior data or explicit relaxation. GO-Diff is trained from scratch using a Boltzmann-weighted score-matching loss, leveraging only the known energy function to guide generation toward thermodynamically favorable regions. The method operates in a two-stage loop of self-sampling and model refinement, progressively improving its ability to target low-energy structures. Compared to traditional optimization pipelines, GO-Diff achieves competitive results with significantly fewer energy evaluations. Moreover, by reusing pretrained models across related systems, GO-Diff supports amortized optimization - enabling faster convergence on new tasks without retraining from scratch.
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Medical Physics
Steerable Conditional Diffusion for Domain Adaptation in PET Image Reconstruction
George Webber, Alexander Hammers, Andrew P. King et al. (+1 more)
Diffusion models have recently enabled state-of-the-art reconstruction of positron emission
tomography (PET) images while requiring only image training data. However, domain shift remains a key concern for clinical adoption: priors trained on images from one anatomy, acquisition protocol or pathology may produce artefacts on out-of-distribution data. We propose integrating steerable conditional
diffusion (SCD) with our previously-introduced likelihood-scheduled
diffusion (PET-LiSch) framework to improve the
alignment of the
diffusion model's prior to the target subject. At reconstruction time, for each
diffusion step, we use low-rank adaptation (LoRA) to align the
diffusion model prior with the target domain on the fly. Experiments on realistic synthetic 2D
brain phantoms demonstrate that our approach suppresses hallucinated artefacts under domain shift, i.e. when our
diffusion model is trained on perturbed images and tested on normal anatomy, our approach suppresses the hallucinated structure, outperforming both OSEM and
diffusion model baselines qualitatively and quantitatively. These results provide a proof-of-concept that steerable priors can mitigate domain shift in
diffusion-based PET reconstruction and motivate future evaluation on real data.
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All authors George Webber, Alexander Hammers, Andrew P. King, Andrew J. Reader
Accelerator Physics
Development of fault identification pipeline for SPIRAL2 LLRF data
Charly Lassalle, Patrick Bonnay, Frédéric Bouly et al. (+2 more)
SPIRAL2 is a state-of-the-art superconducting linear accelerator for heavy ions. The radiofrequency operation of the linac can be disrupted by anomalies that affect its reliability. This work leverages fast, multivariate time series post-mortem data from the Low-Level
Radio Frequency (LLRF) systems to differentiate anomaly groups. However, interpreting these anomalies traditionally relies on expert analysis, with certain behaviours remaining obscure even to experienced observers. By adopting the Time2Feat pipeline, this study explores the interpretability of anomalies through feature selection, paving the way for real-time state observers. Clustering dashboards are presented, allowing the use of multiple clustering
algorithms easily configurable and tools to help for visualizing results. A case study on distinguishing electronic quenches and false quench alarms in postmortem data is highlighted. Thereby, a fast and reliable K-Nearest Neighbours (KNN) classifier is proposed.
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All authors Charly Lassalle, Patrick Bonnay, Frédéric Bouly, Marco Di Giacomo, Adnan Ghribi
Optics · Cross-listed from cond-mat.mtrl-sci
Angular Emission Properties of Strained Transition-Metal Dichalcogenides
Lee Grimberg, Svyatoslav Kostyukovets and Moshe G. Harats
Monolayers of transition-metal dichalcogenides have shown that uniaxial strain changes both the photoluminescence emission energy and intensity. The changes are attributed to the band-structure
evolution under tensile strain where both the bandgap decreases and a direct-to-indirect transition occurs. This was shown for relatively high strains, whereas this is not the case at low strain values $<1\%$ in which in this work, we observe the erratic dependency of the photoluminescence intensity at low strain values as a function of strain. We find that the dominant physical property is the dependence of the optical-dipole emission on the
curvature of the substrate. We validate the behavior of the photoluminescence intensity with experimental angular emission spectroscopy (k-space imaging). These findings are supported by Finite-Difference Time-Domain simulations, in agreement with the experimental data. Our findings present the importance of choosing the right substrate for flexible devices based on transition-metal dichalcogenides.
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Physics and Society
The Price-Pareto growth model of networks with community structure
Łukasz Brzozowski, Marek Gagolewski, Grzegorz Siudem et al. (+1 more)
We introduce a new analytical framework for modelling degree sequences in individual communities of real-world networks, e.g., citations to papers in different fields. Our work is inspired by a recent modification of the Price's model, which assumes that citations are gained partly accidentally, and to some extent preferentially. Our work addresses the need to represent the heterogeneity of various scientific domains, as standard homogeneous models fail to capture the distinct growth ratios and citing cultures of different fields. Extending the model to networks with a community structure allows us to devise the analytical formulae for, amongst others, citation counts in each cluster and their inequality as described by the Gini index. We also show that a citation count distribution in each community tends to a Pareto type II distribution. Thanks to the derived model parameter
estimators, the new model can be fitted to real citation and similar networks.
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All authors Łukasz Brzozowski, Marek Gagolewski, Grzegorz Siudem, Barbara Żogała-Siudem