Chemical Physics
Direct separation of intra- and inter-molecular contributions in pulse dipolar EPR experiments
Olga Vojtiskova, Laura Galazzo and Maxim Yulikov
We present a direct method of separating intra- (form factor) and inter-molecular (background) contri- butions in pulse EPR dipolar spectroscopy (PDS) experiments. The form factor/background separation is accomplished by rearranging data measured at two different biradical concentrations, without any fitting fundamentally required. This new data processing method allows to analyse PDS data from
spin concen- trated samples for which background separation was previously unrealistic. In particular, the presented method would be of high importance for studies of
spin labeled biomolecules, especially in respect to the
liquid-
liquid phase separation (LLPS). Furthermore, we propose a simple measurement and data processing protocol to separate the PDS contributions from each phase in LLPS samples. The protocol for the form factor/background separation for RIDME experiment is also discussed
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Chemical Physics
Efficient Deterministic-Stochastic Representation of the Coulomb Operator in Real Space
Nafiz Faiaz, Tucker Allen, Dimitri Bazile et al. (+2 more)
We present an efficient mixed deterministic-
stochastic approach for constructing the Coulomb operator in real space that preserves accuracy across the full spectral range. The dominant long-range components of the interaction are captured deterministically via a compact, low-rank approximation, constructed using Chebyshev-filtered subspace iteration, while the remaining spectral tail is treated using unbiased probing with a small number of
stochastic vectors. The resulting operator is benchmarked within self-consistent field calculations for the extended Hubbard
Hamiltonian on periodic, perturbed, and non-periodic three-dimensional
lattices. We account for
stochastic bias in observables by implementing a jackknife correction. The method systematically improves with deterministic rank and
stochastic sample count, while substantially reducing the computational cost of constructing the Coulomb
matrix.
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All authors Nafiz Faiaz, Tucker Allen, Dimitri Bazile, Kajsa Williams, Daniel Neuhauser
Fluid Dynamics
Stable, Compact, and Direct Ghost-Cell Reconstruction: A Non-Iterative Approach for Embedded-Boundary Methods
Narsimha Reddy Rapaka, Pankaj Jagad, Yacine Addad et al. (+1 more)
A direct, analytical, non-iterative ghost-
cell reconstruction framework is developed for Cartesian-grid embedded-boundary methods. Analytical expressions impose Dirichlet and Neumann boundary conditions directly at the embedded boundary, eliminating intermediate image-point reconstruction,
matrix inversion, and precomputation or storage of geometry-dependent reconstruction weights. For the Cartesian stencil considered, dependencies among neighboring ghost
cells form a directed acyclic graph. A topological ordering partitions ghost
cells into dependency levels, permitting level-by-level reconstruction without iterative updates. The formulation is combined with hybrid ghost
cells (HGC), whose centers may lie on either side of the embedded boundary. This placement satisfies the linear reconstruction-stability criterion previously derived for scalar advection while retaining a compact nearest-neighbour Cartesian stencil. An extended-stencil classical ghost-
cell formulation (CGC_ES) serves as a stability-preserving reference, distinguishing the effects of reconstruction stability and stencil compactness. The same analytical relations provide solution values and spatial gradients directly on the embedded boundary, enabling evaluation of pressure forces, wall stresses, drag, and lift without separate surface reconstruction or filtering. Simulations of flow past a circular cylinder and an airfoil show that the linear criterion remains a useful indicator of reconstruction stability for the nonlinear incompressible Navier-Stokes cases considered. Classical ghost-
cell reconstruction develops spurious oscillations when the criterion is violated, whereas CGC_ES and HGC remain stable. HGC additionally satisfies the stability requirement with a compact nearest-neighbour stencil.
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All authors Narsimha Reddy Rapaka, Pankaj Jagad, Yacine Addad, Mohamed Kamel Riahi
Chemical Physics
Resolving the ground state intersection problem in coupled cluster theory
Leo Stoll, Federico Rossi and Henrik Koch
A physically correct description of ground state conical intersections is essential for simulating non-adiabatic dynamics of radiationless decay to the electronic ground state. Coupled cluster theory offers a particularly balanced treatment of static and dynamic correlation in excited states. However, coupled cluster methods and other single-reference approaches fail to describe ground state intersection regions, and several workarounds have been proposed to address this shortcoming. Here we present convex similarity constrained coupled cluster theory (CVX-SCC), a framework that resolves the ground state intersection problem by construction. We have applied this theory to two different coupled cluster methods, and tested the resulting models on ethylene, uracil, PSB3, and HeH$_2$, showing that both variants produce physically correct ground state conical intersections. With future development of
nuclear gradients and non-adiabatic coupling vectors, this approach will provide single-reference electronic structures suitable for non-adiabatic dynamics simulations all the way to the ground state.
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Instrumentation and Detectors
Post-fabrication trimming of a 1024-pixel, single-photon counting, Microwave Kinetic Inductance Detector array with a pixel pitch of 150 micron
Wilbert Ras-Vinke, Hessel Schulte, David J. Thoen et al. (+5 more)
Microwave Kinetic Inductance Detectors are superconducting resonators capable of single-
photon counting with energy resolving capability at visible and near-infrared wavelengths. Their zero read noise, extremely low dark counts, and compatibility with frequency-division multiplexing make them well suited for large imaging arrays. The detector yield of these arrays is often limited by the fabrication-induced frequency scatter leading to resonator collisions. We find that the tight packing of the pixels can add significant frequency scatter as well. We developed a post-fabrication correction method that is suitable for tightly packed arrays with a pixel pitch of $150\ \mathrm{\mu m}$. We demonstrate this method on a 1024-pixel array multiplexed on a single octave of readout bandwidth and show a reduction in frequency scatter from $1.1\times 10^{-2}$ to $3.5\times 10^{-4}$ and an increase in yield from $76\%$ to $94\%$.
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All authors Wilbert Ras-Vinke, Hessel Schulte, David J. Thoen, Kevin Kouwenhoven, Steven A.H. de Rooij, Tonny A.H.M. Coppens, Jochem J.A. Baselmans, Pieter J. de Visser
Applied Physics · Cross-listed from cond-mat.mes-hall
Reconfigurable field-free spin Hall nano-oscillators enabled by crystallographic anisotropy in epitaxial Co/Pt
Jong-Guk Choi, Avinash Kumar Chaurasiya, Jaimin Kang et al. (+9 more)
Spin Hall nano-oscillators (SHNOs) are nanoscale microwave sources for wireless communication, neuromorphic computing and oscillator-based Ising machines, but conventional devices require a global
magnetic bias. Here we replace this bias through crystallographic anisotropy in epitaxial Co/Pt. Growth of hcp Co with its c-axis in the film plane produces an anisotropy field of about 0.36 T and enables field-free auto-oscillations above 10 GHz in nanoconstriction SHNOs. The active current polarity is selected by the remanent magnetization, providing nonvolatile reconfiguration of the oscillation state. Micro-focused Brillouin light scattering confirms that the nonlinear response is confined to the nanoconstriction region. Lithographic control of the angle between the current and anisotropy axes tunes the excitation threshold and drives two spectral branches from separated modes to a dominant single branch, consistent with mutual synchronization. These results establish epitaxial crystallographic anisotropy as a route to reconfigurable field-free spintronic oscillators and oscillator networks.
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All authors Jong-Guk Choi, Avinash Kumar Chaurasiya, Jaimin Kang, Venkatesh Vadde, Peter G. Lim, Roman Khymyn, Ahmad A. Awad, Akash Kumar, Mark C. Hersam, Vinayak P. Dravid, Pedram Khalili Amiri, Johan Åkerman
Instrumentation and Detectors
Development of Ultrafast and Radiation-Hard GAGG for the Next-Generation of High-Energy Physics Calorimeters
Louis Roux, Loris Martinazzoli, Julie Delenne et al. (+9 more)
The
evolution of High Energy Physics (HEP) toward future
collider experiments with High Luminosity (HL), such as the HL-LHC, requires the development of scintillating materials that combine high density, excellent radiation hardness and an ultrafast response. While Cerium-doped Gadolinium Aluminum Gallium Garnet (GAGG:Ce) offers a very high light yield and resilience to irradiation, its typical decay time of approximately 50-60 ns may lead to pile-up effects in high-rate environments. In this paper, we report on the development and multi-stage characterization of various accelerated GAGG compositions optimized for timing performance and grown by Crytur. By taking advantage of divalent co-doping to engineer the scintillation kinetics, we achieved an effective decay time (tau_d,eff) down to 5.5 ns while maintaining a competitive light yield of several thousand
photons per MeV. Laboratory characterization demonstrates that the time resolution under gamma-ray excitation is comparable to commercial GAGG, while the time resolution measured with 120 GeV pions reaches performance levels comparable to state-of-the-art LYSO:Ce,Ca. After a 1 MGy
proton irradiation campaign the material retains most of its optical transmission. The results confirm that this ultrafast GAGG composition is a viable candidate for the next generation of HEP calorimetry and timing detectors.
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All authors Louis Roux, Loris Martinazzoli, Julie Delenne, Philipp Roloff, Ondřej Zapadlík, Jan Polak, Jan Havlíček, Silvia Sýkorová, Martin Nikl, Pavel Boháček, Christophe Dujardin, Etiennette Auffray
Optics · Cross-listed from quant-ph
Multiparameter quantum bounds for entanglement-assisted aperture synthesis
Kalaga Madhav, Pieter Kok and Nic Scott
Entanglement-assisted optical interferometry promises diffraction-limited imaging over baselines where light cannot be physically combined, but existing theory treats only a single visibility on one two-station baseline. This work formulates the multiparameter estimation problem for an M-station array imaging an extended scene. A reduction lemma shows that the multimode
quantum Fisher information (QFI) equals the mean
photon number times the QFI of a single delocalized
photon, collapsing the problem to a finite-dimensional one. The local
photon-number superselection rule (SSR) erases all phase information from the bare state, while shared
entanglement restores a fraction f(r)=r/(1+r) of the QFI on a baseline supplied with r pairs – a factor shown to be achievable, since the reduced two-mode state of any pair is exactly the two-station weak-thermal state. The QFI
matrix and its mean Uhlmann
curvature reveal numerically that a point source is measurement-compatible, whereas for every extended-source model examined it is incompatible, the Holevo bound exceeding the symmetric-logarithmic-derivative (SLD) bound by up to ~74%. An explicit collective receiver – a global mode-sorting (
quantum Fourier transform) measurement – then attains a weighted variance within ~7% of the SLD bound and roughly an order of magnitude below an explicit pairwise receiver, and a noisy-resource advantage threshold gives the break-even baseline (~20 km for near-term parameters) beyond which repeater-distributed
entanglement beats direct transmission. Finally, the optimal allocation of a finite
entanglement budget is a convex program with a closed-form proportional (square-root-law) solution favoring low-visibility baselines. These results recast
quantum aperture synthesis as collective multiparameter estimation and give concrete design targets, illustrated on the CHARA array.
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Chemical Physics
Modeling electrolytes in nanopores by Monte Carlo simulations and the Bazant–Storey–Kornyshev model
Nader Nekoubin, David Fertig, Dezső Boda et al. (+1 more)
We study electrolyte-filled cylindrical nanopores through Monte Carlo (MC) simulations and the Bazant–Storey–Kornyshev model, for different ionic valencies, sizes, and bulk concentrations, pore radii and surface charge densities. Our model accounts for finite ion size through a Stern layer and we use de~Souza and Bazant's mechanical
equilibrium principle to derive a boundary condition for the outer Helmholtz plane. For 1:1 electrolytes and moderate surface charge densities, we find that both the classical Poisson–Boltzmann–Stern (PB–Stern) and our Bazant–Storey–Kornyshev–Boltzmann–Stern (BSKB–Stern) model fit MC data well—for 2:1 and 3:1 electrolytes, the BSKB–Stern outperforms the PB-Stern model. Conversely, the BSKB–Stern model poorly fits MC data in other scenarios. First, BSKB–Stern does not capture drying and apparent like-charge attraction in 3:1 electrolytes and small surface charge densities. Second, BSKB–Stern only fits MC data for finely-tuned ionic diameters; for other ionic diameters, the ionic charge densities show oscillations or extended near-surface regions caused by ionic packing and strong Coulomb interactions, not captured by the BSKB–Stern model.
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All authors Nader Nekoubin, David Fertig, Dezső Boda, Mathijs Janssen
Optics
Laboratory X-ray Microscopy Using Fresnel Zone Plate: Method and Practice
Yongshuai Ge and Yuhang Tan
This book was written to share our experience in developing a Fresnel zone plate (FZP) based X-ray microscope. The research began in September 2020, when we were going to build such a scientific imaging instrument from scratch in our laboratory. At that time, we could not find a textbook that systematically explained the entire development process step by step. We therefore had to make progress through trials and mistakes. After nearly five years of hard effort, we finally managed to build such an X-ray microscope in April 2025. Through this experience, we came to realize how challenging it can be to develop a new FZP-based X-ray microscope without systematic guidance. We therefore believe that it is worthwhile to share the learned lessons with readers who may be interested in developing their own FZP-based X-ray microscopes in the future. I would encourage readers to treat this book as a practical manual rather than a traditional textbook. Readers are not expected to be experts in X-ray imaging. Instead, a basic background in college-level physics should be sufficient to understand most of the material. Inevitably, the current edition has limitations and may contain omissions or inaccuracies due to the authors' limited experience and perspective. I sincerely welcome comments, suggestions and discussions from readers, please feel free to contact me at geyongshuai1987@qq.com. Your feedback will be greatly appreciated and will help make future editions of this book more complete.
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Fluid Dynamics · Cross-listed from math.AP
Finite-time divergence of kinetic-energy fluctuations in a Schrödinger-induction flow
Weishuo Liu
In this study, we use a constrained Schrödinger–induction system to investigate kinetic-energy fluctuations induced by a fluid singularity. Assuming the cited Navier–Stokes construction with zero initial velocity and its exact exterior profile, we construct a periodic trajectory from a constant normalized wave function and zero connection. The prescribed body force admits a smooth space–time extension across the normalized singular time $t=1$. In this construction, the probability density remains constant and the mean matter kinetic energy stays bounded, whereas the gauge-invariant kinetic-energy variance diverges. We prove a lower growth bound of order $(1-t)^{-1/2-5h}$, with $h$ fixed by the source construction, by integrating the fourth power of the complete velocity's magnitude over an exact exterior region where all oscillatory corrections vanish. After fixing a gauge with constant wave function, we identify a unique weak $L^2$ connection limit outside $L^4$ and construct its positive self-adjoint kinetic operator through the associated
magnetic form. We further show that the normalized endpoint state belongs to the form domain but not the operator domain: its first kinetic spectral moment is finite, whereas its second is infinite. These results connect fluid concentration to a loss of kinetic-domain regularity and provide a dynamical
benchmark for assessing the limits of mean-energy control in hydrodynamic wave formulations.
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Optics
Expanding RCWA capabilities with advanced S-matrix algorithms
Philippe Lalanne and Jean-Paul Hugonin
Modal methods are particularly well suited to layered photonic structures because electromagnetic propagation within each layer is described analytically. Here, we introduce a simple reformulation of the scattering-
matrix (S-
matrix) approach in which the S-
matrix is defined as an intrinsic property of an individual layer, independently of its neighboring interfaces. This separation between layer propagation and interface coupling preserves the numerical stability of the conventional S-
matrix formalism while providing a more modular description of multilayer structures. It also enables direct computation of the scattering coefficients between external plane waves and Bloch modes, as well as between Bloch modes themselves, providing generalized Fresnel coefficients for periodic interfaces. In addition, the reformulation allows the optical response to be evaluated simultaneously for many layer thicknesses or incident wavevectors, with only a modest computational overhead compared with a single calculation. Implemented in the RETICOLO freeware, these capabilities provide a practical framework for modal analysis, parameter sweeps, and the design of layered photonic structures.
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Optics
Transition of Photonic Dissipative Dynamics through the Exceptional Point
Yue Cui, Ruihen Jin, Xiong Jiang et al. (+3 more)
The decay of light in an optical structure depends not only on the intrinsic properties of the material but also on the surrounding electromagnetic environment. This principle has laid the foundation for the engineering of dissipation in photonic emitters. In the conventional wisdom, dissipation is governed by a fixed set of decay channels, each defined by the eigenstates of the structure, and energy leaks through and interacts with these channels. Here we provide experimental evidence that this paradigm fails in non-Hermitian systems. Specifically, we observe an accelerated transient decay in a pair of coupled microcavities tuned near the exceptional point, revealing that photonic dissipation can be governed not by reconfiguring existing loss channels, but rather by restructuring the underlying state space. The universality of this phenomenon is corroborated through two independent control parameters.The finding provides a new perspective on dissipative dynamics in open optical systems and offers a distinct mechanism for controlling transient decay in ultrafast photonic systems.
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All authors Yue Cui, Ruihen Jin, Xiong Jiang, Kaiyang Wang, Can Huang, Qinghai Song
Optics
Non-Hermitian Light Beams
Andrey Novitsky, Dongliang Gao, Iryna Kaputskaya et al. (+4 more)
Non-Hermitian systems provide remarkable features actively studied in modern photonics. Non-Hermiticity is often related to the properties of open structures and devices, which involve lossy and gain channels. Here, we reveal that electromagnetic fields themselves can be designed in a non-Hermitian way, proposing an additional degree of freedom in non-Hermitian physics. Within classical electromagnetic wave theory, we show that the non-Hermitian behaviors may stem not only from the dispersive properties of the waves, but also from the peculiarities of the light spatial spectrum and local structure of the fields. For the nondiffracting light beams, we identify exceptional points detaching symmetric and asymmetric non-Hermitian phases related to the shape of the beam's intensity profile, the non-Hermiticity being well recognized only for non-paraxial beams. In the local structure of the electromagnetic fields and Poynting vector, we determine exceptional lines differentiating non-Hermitian phases stemming from the behavior of streamlines. We believe that the concept of non-Hermitian light beams will enrich our knowledge of the light-matter interaction.
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All authors Andrey Novitsky, Dongliang Gao, Iryna Kaputskaya, Dawei Li, Andrey Bogdanov, Lei Gao, Mikhail Rybin
Computational Physics
Signature of Short-Range Order in Static Response of the Three-Dimensional Electron Gas
Muhammed H. Güneş, Yubo Yang, Vitaly Gorelov et al. (+4 more)
The three-dimensional electron gas is a fundamental model in condensed matter physics and
quantum chemistry, and the exchange-correlation energy derived from it serves as the starting point of ab initio computations of materials. However, the wave-vector-dependent response, and hence the static local field factor $G(q)$, has remained without accurate ground-state
benchmark in the strongly coupled regime for three decades. Using
diffusion Monte Carlo, we calculate $G(q)$ and the static density-density response function across the
liquid phase and find a pronounced structure in $G(q)$ at intermediate wave vectors, already visible at metallic densities and growing with increasing interaction strength. We identify it as a fingerprint of short-range order by showing that it is required to reproduce the static structure factor. Our parametrization, valid in the entire
liquid phase, predicts a low-energy resonant mode inside the particle-hole continuum.
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All authors Muhammed H. Güneş, Yubo Yang, Vitaly Gorelov, Miguel A. Morales, Matteo Gatti, Lucia Reining, Shiwei Zhang
Applied Physics
A Multi-Model Non-Intrusive Reduced-Order Framework for Parametric Erosion Prediction via Kinematic Cross-Moment Compression
Animesh Yadav, Rajesh Kumar Shukla and Ravinder Kumar Duvedi
High-fidelity Eulerian–Lagrangian simulations of solid particle erosion in curved pipes require hours of compute per operating point, preventing rapid parameter sweeps and real-time wear assessment. Existing reduced-order models (ROMs) speed up these evaluations, yet they are typically trained on a single, fixed empirical erosion formula (e.g., Oka or Finnie). Changing the material law or target hardness then requires a complete retrain of the surrogate. Here, we present a non-intrusive reduced-order framework that avoids this model-locking by approximating the underlying particle collision kinematics instead of scalar wear rates. Specifically, we project and compress 23 Eulerian boundary cross-moments ($\mathbb{E}[V_p^u \sin^v\alpha_p \cos^w\alpha_p]$) across the pipe surface. Using 372 high-fidelity CFD-DPM cases of $90^\circ$ elbows over three bend ratios ($R/D \in \{1.5, 2.0, 5.0\}$), five Reynolds numbers, five density ratios, and six particle diameters in the inertial regime ($St > 1$), we evaluate a hybrid compression scheme. Linear Proper Orthogonal Decomposition (POD) and Mode-1 tensor unfolding SVD are combined with block-wise Convolutional Autoencoders (CNN-AE) to handle both broad convective transport and localized impact craters. An anisotropic Gaussian Process Regression (GPR) surrogate maps four dimensionless $\Pi$-groups to the compressed latent space, evaluating full 2D wear topographies in roughly $2\,\mathrm{ms}$ ($R^2 > 0.99$ on primary kinematic fields). Because kinematics are decoupled from material damage laws, the resulting surrogate evaluates multiple empirical models post-hoc exactly matching Finnie and closely approximating Oka, McLaury, and Arabnejad without retraining.
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Chemical Physics
Analytic Gradients and Nonadiabatic Couplings for Device-Resident DMRG-QD-NEVPT2 Through Conical Intersections on a Consumer GPU
Rubén Darío Guerrero
Nonadiabatic dynamics through a conical intersection requires both static and dynamic correlation and, at every geometry, an excited-state gradient and interstate nonadiabatic coupling (NACME). Analytic multireference derivatives at this level have been confined to datacenter-scale hardware. We report device-resident \mbox{DMRG-QD-NEVPT2} with analytic gradients and NACMEs within the $8$\,GB of a consumer GPU: a density-
matrix-renormalization-group (DMRG) active-space reference supplies the static correlation, and quasi-degenerate SC-NEVPT2 dresses it through a multi-state effective
Hamiltonian that remains valid through a conical intersection, where single-state perturbation theory develops a vanishing denominator and fails. Every gradient and NACME is one reverse-mode transpose of a single contraction graph: the DMRG sweep enters as a gauge-free differentiable node, and all two-electron work is AO-direct through Cholesky factors. The DMRG reference is exact within the active space ($\sim\!10^{-15}$\,Ha). The corrected adiabats close smoothly to a real $S_0/S_1$ conical intersection with a non-vanishing, $1/\Delta E$-divergent NACME—where linear-response TDDFT returns zero identically—and the dressing restores the differential dynamic correlation that ionic $\pi\pi^*$ states require. DMRG-NEVPT2 and quasi-degenerate NEVPT2 are each established; what is new is the combined stack—multi-state and through a conical intersection, with analytic gradients and couplings—realized device-resident on commodity hardware.
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Instrumentation and Detectors
A unified quantum electrical platform for synchronous metrological realization of volt, ohm and ampere
Lei Wang, Lushuai Qian, Yunfeng Lu et al. (+12 more)
A co-located integration
quantum electrical standard is essential to reduce reliance on distributed traceability in high-accuracy metrology, especially for portable and on-site use. Metrologically, realizing any two of voltage, resistance, and current is sufficient, as the third follows from Ohm's law. The combination of Josephson voltage and
quantum Hall resistance offers better uncertainty, but conflicts with the tesla-level field for
quantum Hall and near-zero field for Josephson operation. Here we report a compact unified platform enabling co-realization of
quantum voltage and resistance in a single cryostat near 4 K, with
quantum current derived via Ohm's law. A hierarchical
magnetic shielding with staged attenuation and spatial confinement allows 6 T and below 50 nT to coexist within 270 mm axial separation with negligible cross-coupling. In integrated operation, the Josephson and
quantum Hall subsystems agree with expected quantized values within relative standard uncertainties of 2.6E-9 and 1.4E-8, respectively. Linking them via an improved cryogenic current comparator realizes a 50 {\mu}A
quantum current with relative uncertainty of 6.6E-8. These results demonstrate that three basic electrical units can be synchronously realized with superior metrological consistency on a single integrated platform, offering a viable transition from distributed calibration chains toward compact-integrated
quantum-based realization.
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All authors Lei Wang, Lushuai Qian, Yunfeng Lu, Yang Shi, Xuanlu Yang, Xiaoding Huang, Zihan Lei, Yuan Zhang, Yaqiong Fu, Junsheng Cheng, Jianhua Liu, Xinning Hu, Yinming Dai, Jianting Zhao, Qiuliang Wang
Chemical Physics
More is not always better: Dissociative photoionization limits the EUV absorbing photoacid generator pentafluorophenyl triflate in photolithography
Fabian Holzmeier, Michiel J. van Setten, Ragnar Björnsson et al. (+3 more)
Pentafluorophenyl triflate has been explored as a highly absorbing neutral photoacid generator (PAG) candidate for next generation chemically amplified resists used in extreme ultraviolet (EUV) lithography. Although increased fluorination enhances EUV absorption, this study demonstrates that such an approach does not necessarily improve photoacid generation efficiency. Using photoelectron-photoion coincidence (PEPICO) spectroscopy at the 92 eV
photon energy of the EUV scanners in combination with
quantum chemical calculations, the dissociative photoionization of pentafluorophenyl triflate was systematically investigated. The photoionization mass spectrum reveals extensive fragmentation, with the parent ion contributing only 3.1 % of the total signal and CF$_3^+$ representing the dominant product ion. Computed appearance energies align well with experimental trends and support a sequential fragmentation pathway involving loss of SO$_2$, CF$_3$, and CO. Crucially, none of the major dissociation channels yield precursors capable of forming triflic acid, the strong photoacid required for efficient deprotection reactions in chemically amplified resists. Combined with previous dissociative electron attachment studies indicating similarly unfavorable fragmentation, the results demonstrate that despite its high EUV absorption cross section, pentafluorophenyl triflate is unsuitable as a PAG for EUV lithography. The findings highlight the importance of understanding fundamental photoionization and electron interaction mechanisms to guide the rational design of next generation high performance EUV photoresists.
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All authors Fabian Holzmeier, Michiel J. van Setten, Ragnar Björnsson, Robert Richter, Filipe Ferreira da Silva, Oddur Ingólfsson
Applied Physics
An angular distortion matrix approach for joint wave-speed tomography and aberration correction in scattering media
Chenyu Cui, Flavien Bureau, Foucauld Chamming's et al. (+2 more)
Despite being one of the most fundamental properties governing wave propagation, the wave-speed distribution is rarely known accurately in reflection imaging. Its estimation relies on analyzing wave distortions undergone by the incident and reflected waves; however, their contribution is difficult to disentangle from the medium reflectivity, particularly in complex media dominated by speckle. Mismatches between assumed and actual wave speeds result in aberrations that degrade the quality of reflectivity images. Yet these aberrations carry information about the underlying wave-speed heterogeneities. Here, we show that an angular distortion
matrix, built upon
matrix imaging, can unscramble this information to map the wave speed and correct aberrations across the entire field of view. At each point, this
matrix isolates the distortions accumulated by the incident and reflected waves along well-defined propagation directions. It reveals strong angular correlations that can be exploited through time-reversal analysis to estimate local phase aberrations, providing observables for wave-speed
tomography. The resulting map improves the propagation model used for
matrix imaging, after which the process is iterated to refine the wave speed until residual aberrations become negligible. Using ultrasound as proof of concept, we validate the approach in a tissue-mimicking phantom and illustrate its clinical potential in vivo for breast and liver imaging. Sound-speed maps show contrast consistent with a malignant breast lesion and expected values in a healthy liver, while aberration correction sharpens reflectivity images routinely interpreted by clinicians. Beyond ultrasound, the approach extends naturally to any wave modality in which reflection-
matrix imaging can be implemented.
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All authors Chenyu Cui, Flavien Bureau, Foucauld Chamming's, Alexandre Aubry, Naiara Korta Martiartu
Optics
Image recognition based on optical spike processing with exciton-polaritons
Olgierd Jeziorski, Jakub Rogala and Krzysztof Tyszka
Exciton-polariton condensates combine ultrafast dynamics with strong optical nonlinearities, making them promising for optical neuromorphic computing. Here, we numerically demonstrate image recognition using the transient response of an
exciton-polariton condensate. Downscaled MNIST images are encoded as optical pulse sequences, and the resulting condensate dynamics are sampled and processed by a linear classifier. For ten-class classification, condensate features achieve 92.2% accuracy, compared with 91.4% for raw-pixel linear classification. Combining both feature sets increases the accuracy to 93.2%. For the challenging binary classification of digits 7 and 9, the combined model reaches 97.3%, exceeding both the linear (95.5%) and feed-forward neural-network (96.6%) baselines. These results demonstrate that polariton dynamics can extract useful nonlinear features for ultrafast optical information processing.
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History and Philosophy of Physics
Is Black Hole Evaporation Prediction Friendly?
Dominic John Ryder
Manchak and Weatherall (2018) formulate the black hole information paradox as a failure of predictability in black hole evaporation spacetimes, diagnosed by non-global hyperbolicity. I offer a strategy for resolving this paradox. I argue that failures of predictability in black hole evaporation are not well diagnosed by non-global hyperbolicity. I then consider two weakenings of global hyperbolicity: prediction and retrodiction friendliness, the failure of which could ground a new paradox. However, deidealized black hole evaporation models can be prediction and retrodiction friendly. Therefore, the information paradox cannot be based upon failures of global hyperbolicity, nor either retrodiction or prediction unfriendliness.
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Applied Physics
Spectral Geometry and Dispersion-Constrained Projection of Diffusive Fields
Pengfei Zhu, Julien Lecompagnon, Philipp Daniel Hirsch et al. (+1 more)
Diffusive fields obey operator-imposed relations between spatial structure and temporal decay, yet conventional spectral filtering selects components primarily according to frequency or wavenumber magnitude. Here we show that the
diffusion operator defines a spectral geometry in the joint space of spatial wavenumber and modal decay rate, where physically admissible modes occupy the
manifold $\eta=\alpha|\mathbf{k}|^2$. This geometry separates spectral scale from physical consistency: high-wavenumber modes can remain
diffusion-consistent, whereas lower-wavenumber modes can violate the governing dynamics. We exploit this distinction by introducing an operator residual and a finite-width soft projection that selects spectral components according to their distance from the
diffusion manifold rather than their spectral magnitude. Numerical studies demonstrate robust recovery under noise, diffusivity mismatch, and finite acquisition, and reveal a consistency–retention tradeoff governed by the
manifold width. Photothermal experiments further confirm that the projection suppresses off-
manifold spectral content while retaining the dominant thermal response. These results establish operator consistency as a spectral-selection principle for diffusive fields and provide a
geometric framework for physics-informed processing of dissipative systems.
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All authors Pengfei Zhu, Julien Lecompagnon, Philipp Daniel Hirsch, Mathias Ziegler
Instrumentation and Detectors
A Six-Quadrupole Diamagnetic Suspension Architecture for Ultra-Sensitive Space Accelerometry
Marco Pisani, Edoardo Dalla Ricca, Carlo Paolo Sasso et al. (+1 more)
This paper proposes a novel inertial sensor based on a solid diamagnetic cubic test mass passively suspended by a symmetric configuration of six
magnetic quadrupoles. Designed specifically for microgravity environments, this system eliminates the mechanical noise and hysteresis inherent in elastic suspensions, as well as the complexity associated with electrostatic suspension systems. We provide an analysis of the
magnetic intrinsic noise floor imposed by eddy current damping, alongside ground-based preliminary experimental results demonstrating potential sensitivities in the order of the $10^{-10} \text{ m/s}^2/\sqrt{\text{Hz}}$ regime.
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All authors Marco Pisani, Edoardo Dalla Ricca, Carlo Paolo Sasso, Massimo Zucco
Plasma Physics
High-charge, highly polarized positron beams generated from a laser-driven nanowire-array target
De-Sheng Zhang, Cui-Wen Zhang, Kun Xue et al. (+4 more)
The generation of high-charge, highly polarized positron beams in the interaction of a linearly polarized
laser pulse with a nanowire-array target is investigated. Here,
laser-driven electrons emit high-energy
photons through nonlinear Compton scattering (NCS), which subsequently produce electron–positron pairs through the nonlinear Breit–Wheeler (NBW) process. We model this interaction using two-dimensional
spin-resolved
quantum electrodynamics particle-in-
cell (QED-PIC)} simulations. At positron birth, the sign of $S_z$ is statistically correlated with that of the local $B_z$. The spatiotemporal field structure arising from the
laser–nanowire interaction strengthens the correlation between the birth
spin sign and the direction of the subsequent transverse Lorentz impulse, thereby limiting cancellation between opposite-
spin contributions at a given angle. The results show that the average polarization degree reaches $|\bar S_z|\approx0.46$, and the positron charge satisfying $|\bar S_z|>0.3$ is approximately $308\,\mathrm{nC}$. Parameter scans reveal that the high-polarization positron charge is maximized at intermediate target densities and nanowire periods. Such a source could enable polarization-sensitive studies of strong-field QED and
spin-dependent phenomena in high-energy and materials physics.
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All authors De-Sheng Zhang, Cui-Wen Zhang, Kun Xue, Feng Wan, Xue-Ren Hong, Jian-Xing Li, Bai-Song Xie
Atomic Physics
Miniaturized vacuum package for magneto-optical trapping of strontium
Julian Pick, Eric Henker, Florian Löwinger et al. (+17 more)
Quantum sensors, like optical
lattice clocks, undergo a continuous development from lab-based towards mobile systems. A key aspect in the miniaturization of the experimental setups is the development of compact atom sources. Conventional atom sources for alkaline-earth-like elements consist of a high-power oven and a six-beam magneto-optical trap (MOT) inside of
vacuum chamber with extensive flanges, viewports and electrical feedthroughs. Here we present a highly compact
vacuum package utilizing key technologies for future
quantum sensor systems: A chip-based low-power atomic oven, a planar grating MOT chip, and a miniaturized
vacuum pump all held inside an additively manufactured titanium
vacuum chamber, featuring custom-sized
vacuum flanges. In this miniaturized setup, spanning a volume of only 750 ml, we trap up to $10^5$ Sr atoms in a MOT, requiring an oven heating power below 1 W.
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All authors Julian Pick, Eric Henker, Florian Löwinger, Rick Vogt, Sebastian Hüttl, Andreas Trützschler, Julia Voß, Simon Hirt, Malte Schulz-Ruhtenberg, Aleksandra Buchta, Alexander Kassner, Folke Dencker, Marc Wurz, Stephan Hannig, Simone Callegari, Saskia Bondza, Jens Kruse, Tobias Leopold, Roman Schwarz, Carsten Klempt
Instrumentation and Detectors
Operation of a negative ion gas time projection chamber without electronegative fill gases
Lachlan J. McKie, Lindsey J. Bignell, Nicholas Adams et al. (+3 more)
The high fidelity reconstruction of particle tracks in micropatterned gaseous time projection chambers renders this technology ideal for future rare-event searches, including direction-sensitive dark matter experiments. Large drift distances are typically required for such experiments, so that the overall spatial resolution is limited by
diffusion. Negative ion drift exhibits lower
diffusion than electron drift and is thus an attractive option for realising a large-scale detector. The use of electronegative gases to create negative ions introduces technical challenges, most notably a reduction in gain when compared to conventional gas mixtures. In this study, we demonstrate a new method for negative ion generation via dissociative electron attachment using the conventional molecular fill gas CF$_4$. Our optical measurements of negative ion drift indicate electron attachment lengths of $<$1 mm and comparable gain to electron avalanches. The individual negative ion avalanches were also time-resolved, allowing the number of ions reaching the readout to be counted. We measure an improved energy resolution by single ion counting, relative to an integrated electron avalanche signal measured under identical gain conditions.
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All authors Lachlan J. McKie, Lindsey J. Bignell, Nicholas Adams, Victoria U. Bashu, Ferdos Dastgiri, Gregory J. Lane
Optics
Stable vortex soliton arrays in disclination-fractal systems
Shuang Shen, Milivoj R. Belić, Ce Shang et al. (+2 more)
Vortex light fields carry orbital angular momentum and have attracted significant
attention because of their wide applications in light field manipulations, optical communications, and
quantum information processing. In nonlinear media, the balance between diffraction and self-action enables the formation of
vortex solitons. However, achieving the stability of
vortex solitons remains challenging due to radial and azimuthal modulation instabilities. Here, we report stable
vortex solitons and
vortex-
soliton arrays in disclination-fractal configurations with different rotational
symmetries, constructed by applying disclination operations to fractal
lattice structures. The stable
vortex-
soliton arrays—composed of several
vortex solitons—can exist along domain walls, resulting from the disclination operation applied to the topologically trivial phase. Their stability is verified through both linear stability analysis and direct simulations of perturbed propagation. For comparison,
vortex-
soliton arrays in conventional disclination configurations are found to be completely unstable, demonstrating the significance of the fractal configuration in stabilizing these nonlinear states. These findings reveal a new nonlinear excitation mechanism arising from the interplay between fractal geometry and disclination defects, thereby providing theoretical underpinnings for both the improved understanding of multi-field excitation phenomena in complex
geometric systems and opening new avenues for the design of photonic devices based on fractal disclination structures.
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All authors Shuang Shen, Milivoj R. Belić, Ce Shang, Yongdong Li, Yiqi Zhang
Atomic Physics · Cross-listed from astro-ph.SR
Validity of the CRD limit for modeling scattering polarization in the photospheric Sr I 4607 Å line
Simone Riva, Gioele Janett, Franziska Zeuner et al. (+3 more)
Context. Scattering polarization in the Sr I 4607 Å line is a key diagnostic for small-scale, unresolved
magnetic fields in the quiet
solar photosphere, inaccessible to Zeeman-based techniques. The complete frequency redistribution (CRD) limit is commonly used to model this line, but its validity and impact on
magnetic sensitivity have not been systematically investigated. This is timely given new facilities observing this line with unprecedented accuracy, and future synoptic programs targeting long-term quiet-Sun magnetism. Aims. We assess the CRD limit against the general partial frequency redistribution (PRD) description of scattering for the Sr I 4607 Å polarization, focusing on its
magnetic sensitivity via the Hanle effect. Methods. We solved the non-LTE radiative transfer problem for polarized radiation in a semi-empirical 1D plane-parallel static atmosphere, with CRD and PRD scattering, across
magnetic field configurations relevant for Hanle diagnostics. Results. For small-scale unresolved fields, where the field acts only via Hanle depolarization of Q/I, CRD and PRD emergent profiles and Hanle sensitivity are essentially identical. For deterministic fields, CRD remains accurate when polarization signals exceed about 0.3%; for weaker signals, PRD effects can appreciably affect the emergent profiles. Conclusions. CRD is adequate for modeling Sr I 4607 Å scattering polarization in the vast majority of observationally relevant cases; PRD effects matter only for weak polarization signals.
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All authors Simone Riva, Gioele Janett, Franziska Zeuner, Luca Belluzzi, Fabio Riva, Pietro Benedusi
Chemical Physics
Comprehensive Study of L-Menthol and Octanoic Acid as a Hydrophobic Eutectic Solvent
Bernarda Lovrinčević, Martina Požar, Romana Cerc Korošec et al. (+4 more)
Hydrophobic eutectic solvents (HES) based on natural compounds represent promising green alternatives to conventional solvents. In this work, we investigate the physicochemical, structural, and dynamical properties of an ES formed by L-menthol and octanoic acid using a combined experimental and molecular dynamics simulation approach. Five compositions with molar ratios from 1:3 to 3:1 were studied with molecular dynamics simulation in the temperature range 15 degrees C to 35 degrees C. Experimental measurements of density and viscosity in the temperature range from 5 degrees C to 35 degrees C were complemented with results obtained from MD simulations employing the OPLS force field. Structural analyses based on radial distribution functions and Kirkwood-Buff integrals reveal that the dominant interactions in the mixture are hydrogen bonds between L-menthol and octanoic acid molecules. Dynamic properties, including self-
diffusion coefficients and hydrogen-bond lifetimes, indicate that intermolecular hydrogen bonds between the two components are stronger and longer-lived than bonds between identical species. These findings provide molecular-level insight into the structure and transport properties of menthol-based ESs relevant for green solvent applications.
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All authors Bernarda Lovrinčević, Martina Požar, Romana Cerc Korošec, Klara Švegelj, Peter Ogrin, Marija Bešter-Rogač, Tomaž Urbič