Biological Physics
Study of Quantum Confinement inside a Viral Capsid
Elso Drigo Filho and Regina Maria Ricotta
Classical computational methods, such as molecular dynamics and Monte Carlo simulations, have long been the standard for modeling viral structure and function. However, these approaches may overlook crucial
quantum phenomena that operate at the nanoscale, particularly within the highly-compacted genetic material of the viral capsid. The confined, high-density environment of genetic material within the capsid strongly suggests that
quantum confinement effects play a significant, yet unexplored, role in viral processes. This study introduces a novel
quantum approach using Supersymmetric
Quantum Mechanics (SQM) to investigate the
quantum confinement effects on viruses. In this paper, the viral capsid environment is modeled using the Pariacoto virus, a model system well-suited for this analysis due to its specific structural properties. The findings reveal that
quantum effects are not merely marginal but essential for understanding key processes inside the capsid, providing new insights beyond the scope of classical physics.
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Chemical Physics · Cross-listed from quant-ph
Error-Mitigation Enabled Multicomponent Quantum Simulations Beyond the Born-Oppenheimer Approximation
Delmar G. A. Cabral, Brandon Allen, Fabijan Pavošević et al. (+6 more)
We introduce a multicomponent
unitary coupled cluster framework for
quantum simulations of molecular systems that incorporate both electronic and
nuclear quantum effects beyond the Born-Oppenheimer approximation. Using the
nuclear-electronic orbital formalism, we construct mcUCC ansätze for positronium hydride and molecular hydrogen with a
quantum proton, and analyze hardware requirements for different excitation truncations. To further reduce resource costs effectively, we employ the local
unitary cluster Jastrow ansatz and implement it experimentally on IBM Q's Heron superconducting hardware. With the Physics-Inspired Extrapolation error mitigation protocol, the computed ground-state energies remain within chemical accuracy, consistent with the stated uncertainty level. These results provide the first demonstration of error-mitigated multicomponent correlated simulations on
quantum hardware and outline a path toward scalable
algorithms unifying electronic and
nuclear degrees of freedom.
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All authors Delmar G. A. Cabral, Brandon Allen, Fabijan Pavošević, Sharon Hammes-Schiffer, Pablo Díez-Valle, Jack S. Baker, Gaurav Saxena, Thi Ha Kyaw, Victor S. Batista
Atomic Physics · Cross-listed from cond-mat.quant-gas
Lellouch-Lüscher relation for ultracold few-atom systems under confinement
Jing-Lun Li, Paul S. Julienne, Johannes Hecker Denschlag et al. (+1 more)
We derive an analog of the Lellouch-Lüscher (LL) relation for few-body bosonic systems, linking few-body scattering loss rates to the energies and widths of the corresponding harmonically trapped few-body states. Three-body numerical simulations show that the LL relation applies across a broad range of interaction strengths and energies and allows the determination of scattering rates within a single partial wave. Our work establishes a robust theoretical framework for understanding the role of the finite volume effect in few-body observables in optical
lattice and tweezer experiments, enabling precise determination of multi-body scattering rates.
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All authors Jing-Lun Li, Paul S. Julienne, Johannes Hecker Denschlag, José P. D'Incao
General Physics
Classical timing noise in gravity-mediated entanglement tests: LOCC structure, metrological bounds, and visibility thresholds
Yaghmorassene Hebib
Table-top proposals to test
gravity-mediated
entanglement aim to distinguish coherent gravitational interactions from classical dephasing processes that generate identical phases on both interferometers. A particularly important contribution is platform-invariant timing noise, which can be accessed through optical-clock cross-spectra and frequency-transfer links. In this work we (i) derive the mapping from clock cross-spectra to an effective common-mode dephasing rate, (ii) show that the corresponding dynamical channel is LOCC and therefore unable to generate
entanglement, and (iii) combine published clock and interferometer noise floors to obtain quantitative bounds on the ratio between common-mode and local dephasing rates in representative
gravity-
entanglement proposals. Across QGEM-, MAQRO-, and levitated-nanoparticle regimes we find a robust hierarchy $\gamma_{\rm com}/\gamma_{\rm loc}\sim10^{-9}$–$10^{-11}$, identifying platform-invariant timing noise as a negligible but calibratable background. We further derive visibility and Bell–CHSH thresholds in the presence of both common-mode and local dephasing, and illustrate the full calibration workflow with a simple synthetic example anchored to state-of-the-art clock metrology. Extended derivations and statistical tools are provided in the Supplemental Material.
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Applied Physics
Orthogonal Photoelastic Imaging for Three-Dimensional Stress Estimation in a Transparent Cubical Block
Dhiraj K. Singh
Conventional photoelastic methods are largely limited to two-dimensional stress visualization, leaving a gap in techniques that can capture three-dimensional force interactions with high sensitivity at low stress levels, a capability that is critical for biomechanics and dynamic force analysis. This study develops and demonstrates a cubic photoelastic model that enables accurate fringe-order estimation from three orthogonal views, providing a foundation for reconstructing full three-dimensional stress states. A transparent, low-elasticity epoxy cube, free of prestress, was fabricated and examined using combined transmission and reflection photoelastic imaging. Three mutually orthogonal isochromatic fringe fields were recorded simultaneously under a single applied load. Image analysis employed a peak-valley intensity method to extract sub-fringe orders and to resolve low-stress cases with minimal noise. The cubic block produced high-quality fringe patterns in all directions, enabling separation of tangential and normal stress components. Independent orthogonal views confirmed directional sensitivity and yielded consistent fringe-order estimates under low loading, with response times on the order of tens of microseconds. These results establish a practical approach for three-dimensional photoelastic stress measurement from orthogonal views and create a pathway toward full vector force reconstruction with strong potential for biomedical applications and studies of dynamic loading.
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Chemical Physics
Martini Mapper: An Automated Fragment-Based Framework for Developing Coarse-Grained Models within the Martini 3 Framework
Kevin V. Bigting, Shubhadeep Nag and Yaxin An
Coarse-graining (CG) reduces molecular details to extend the time and length scales of molecular dynamics simulations to microseconds and micrometers. However, the CG approaches have long been limited by the difficulty of constructing both accurate and transferable models efficiently, considering the large diversity of chemical structures of materials. Among CG force fields, Martini is the most widely used, as it retains essential chemical features while offering substantial computational efficiency. Its most recent version, Martini 3, expands chemical resolution through a much broader bead set, particularly for small molecules. However, this flexibility also complicates the mapping of organic molecules because of context-dependent rules and the lack of standardized procedures. To address this issue, we present an automated framework that builds Martini 3 models directly from SMILES (Simplified Molecular Input Line Entry System) strings by combining a curated bead dictionary with a hierarchical, rule-based
algorithm and molecule-specific bonded parameters. Our framework, Martini Mapper https://github.com/eliobaby/Martini_mapper, generated Martini 3 models for 6,280 molecules across six chemically diverse
datasets, including 1,689 systems with bond/angle parameters and additional large systems mapped at the topological level. A curated subset of 1,075 mapped structures was benchmarked using transfer free energies in hydrated octanol, hexadecane, and chloroform from water against reference data wherever available. We further examined the
benchmark with structural validation via SASA, yielding good agreement with experimental and atomistic reference data. The workflow can also map large molecules containing up to 172 heavy atoms, exceeding the capabilities of existing automated approaches. Our framework, therefore, enables Martini 3 structures for high-throughput simulations.
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Applied Physics
Mechanosensitive polymer matrices of biologically-relevant compliance based on upconverting nanoparticles
Cindy H. Shi, Mia C. Cano, Jason R. Casar et al. (+5 more)
Upconverting nanoparticles (UCNPs) are promising optical biomechanical force sensors due to their near infrared excitation, low toxicity, photostability, and linear colorimetric sensitivity to micronewtons of force. Recently, a composite force sensor based on UCNPs embedded in a polystyrene microbead enabled the first real time measurement of feeding forces in living nematodes. However, the comparatively large stiffness of polystyrene only makes it relevant to biomedical application in a small subset of biological tissue. To facilitate deployment of UCNPs into biological tissues with a range of mechanical properties, we expand upon
polymer UCNP composite systems by
embedding UCNPs in three
polymer matrices with varying stiffnesses (epoxy resin, polydimethylsiloxane, and alginate hydrogels). Furthermore, to enhance these composites mechanosensitivity, we methodically investigate using two different core-shell architectures of SrLuF based UCNPs doped with ytterbium, erbium, and varying manganese concentrations. We calibrate
polymer UCNP composite optical force sensitivity with colocalized atomic force and confocal microscopy. Using the red to green emission ratio (Delta Percent IRed:IGreen) as the force read-out, we determine that SrLuF:Yb0.28Er0.025Mn0.013 with SrYF inert shell dispersed in epoxy resin exhibits the greatest emission color change (12 Delta Percent IRed:IGreen per microNewton). Finally, we map forces in the epoxy UCNP composite on the macroscale between the joint of a chicken wing bone using a commercially available wide field microscope, thereby demonstrating its ability to optically measure pressures in situ. This work establishes the utility and modularity of the UCNP
polymer composite system for force sensing in geometrically and mechanically diverse biological systems.
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All authors Cindy H. Shi, Mia C. Cano, Jason R. Casar, Parivash Moradifar, Beatriz G. Robinson, Julia A. Kaltschmidt, Miriam B. Goodman, Jennifer A. Dionne
Applied Physics
Phase-field modeling of cyclic behavior in quasi-brittle materials: A micromechanics-based approach
Mina Sarem, Nuhamin Eshetu Deresse, Els Verstrynge et al. (+1 more)
In this paper, we extend a micromechanics-based phase-field framework for fatigue fracture to incorporate cyclic plasticity with ratcheting. This mechanism is particularly relevant for low-cycle fatigue, where the accumulation of inelastic strains plays a critical role in the progression to final failure. An energetic formulation is proposed in which the ratcheting strain is explicitly incorporated into both the free energy and the dissipation potential. Ratcheting is modeled within a pressure-dependent, non-associative plasticity framework through the
evolution of a ratcheting strain that progressively accumulates over loading cycles, capturing the characteristic inelastic strain growth of cyclic plasticity in a thermodynamically consistent manner. The plastic potential is formulated such that the deviatoric and volumetric components of ratcheting can be controlled independently. A staggered solution scheme is employed to solve for the internal variables, including the ratcheting strain. The model is validated through numerical simulations under a wide range of loading conditions, including monotonic and cyclic regimes (stress- and strain-controlled, low- and high-cycle fatigue), enabling evaluation of its performance and the influence of ratcheting on the material response, and demonstrating its applicability to realistic engineering scenarios.
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All authors Mina Sarem, Nuhamin Eshetu Deresse, Els Verstrynge, Stijn François
Physics Education
Categorization of Roles in the Quantum Industry
A.R. Pina, Shams El-Adawy, H.J. Lewandowski et al. (+1 more)
Continued growth of the
quantum information science and engineering (QISE) industry has resulted in stakeholders spanning education, industry, and government seeking to better understand the workforce needs. This report presents a framework for the categorization of roles in the QISE industry based on 42 interviews of QISE professionals across 23 companies, as well as a description of the method used in the creation of this framework. The data included information on over 80 positions, which we have grouped into 29 roles spanning four primary categories. For each primary category we provide an overview of what unites the roles within a category, a description of relevant subcategories, and definitions of the individual roles. These roles serve as the basis upon which we generate profiles of these roles, which include information about role critical tasks, necessary knowledge and skills, and educational requirements. Our next report will present such profiles for each of the roles presented herein.
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All authors A.R. Pina, Shams El-Adawy, H.J. Lewandowski, Benjamin M. Zwickl
Biological Physics · Cross-listed from cond-mat.soft
Topological flowscape reveals state transitions in nonreciprocal living matter
Hyunseok Lee, EliseAnne Koskelo, Shreyas Gokhale et al. (+7 more)
Nonreciprocal interactions – where forces between entities are asymmetric – govern a wide range of nonequilibrium phenomena, yet their role in structural transitions in living and active systems remains elusive. Here, we demonstrate a transition between nonreciprocal states using starfish embryos at different stages of development, where interactions are inherently asymmetric and tunable. Experiments, interaction inference, and topological analysis yield a nonreciprocal state diagram spanning crystalline, flocking, and fragmented states, revealing that weak nonreciprocity promotes structural order while stronger asymmetry disrupts it. To capture these transitions, we introduce topological landscapes, mapping the distribution of structural motifs across state space. We further develop topological flowscapes, a dynamic framework that quantifies transitions between collective states and detects an informational rate shift from the experimental state transition. Together, these results establish a general approach for decoding nonequilibrium transitions and uncover how asymmetric interactions sculpt the dynamical and structural architecture of active and living matter.
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All authors Hyunseok Lee, EliseAnne Koskelo, Shreyas Gokhale, Junang Li, Chenyi Fei, Chih-Wei Joshua Liu, Lisa Lin, Jorn Dunkel, Dominic J. Skinner, Nikta Fakhri
Computational Physics · Cross-listed from cond-mat.mtrl-sci
Edwards Localization
Riccardo Fantoni
We study the localization problem in
quantum stochastic mechanics. We start from the Edwards model for a particle in a bath of scattering centers and prove static localization of the ground state wavefunction of the particle in a one dimensional square well coupled to Dirac delta like scattering centers in arbitrary but fixed positions. We see how the localization increases for increasing coupling $g$ and increasing number of scattering centers at constant density. Then we choose the scattering centers positions as pseudo random numbers with a uniform probability distribution and observe an increase in the localization of the average of the ground state over the many positions realizations. We discuss how this averaging procedure is consistent with a picture of a particle in a Bose-Einstein condensate of of non interacting
boson scattering centers interacting with the particle with Dirac delta functions pair potential. We then study the dynamics of the ground state wave function. We conclude with a discussion of the affine quantization version of the Lax model which reduces to a system of contiguous square wells with walls in arbitrary positions independently of the coupling constant $g$.
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Chemical Physics
Socrates-Mol: Self-Oriented Cognitive Reasoning through Autonomous Trial-and-Error with Empirical-Bayesian Screening for Molecules
Xiangru Wang, Zekun Jiang, Heng Yang et al. (+4 more)
Molecular property prediction is fundamental to chemical engineering applications such as solvent screening. We present Socrates-Mol, a framework that transforms
language models into empirical
Bayesian reasoners through context engineering, addressing cold start problems without model fine-tuning. The system implements a reflective-prediction cycle where initial outputs serve as priors, retrieved molecular cases provide evidence, and refined predictions form posteriors, extracting reusable chemical rules from sparse data. We introduce ranking tasks aligned with industrial screening priorities and employ cross-model self-consistency across five
language models to reduce variance. Experiments on amine solvent LogP prediction reveal task-dependent patterns: regression achieves 72% MAE reduction and 112% R-squared improvement through self-consistency, while ranking tasks show limited gains due to systematic multi-model biases. The framework reduces deployment costs by over 70% compared to full fine-tuning, providing a scalable solution for molecular property prediction while elucidating the task-adaptive nature of self-consistency mechanisms.
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All authors Xiangru Wang, Zekun Jiang, Heng Yang, Cheng Tan, Xingying Lan, Chunming Xu, Tianhang Zhou
Physics and Society
Simulating Keystroke and Computing the Theoretical Probability of Infinite Monkey Theorem with Markov Process
Juncheng Yi, Kaiwen Zhou and James Jiang
The Infinite Monkey
Theorem states that if one monkey randomly hits the keys in front of a typewriter keyboard during an infinite amount of time, any works written by William Shakespeare will almost surely be typed out at the end of the total text. Due to the seemingly low chance of typing the exact literature works, our group are motivated to find out the expected time the Hamlet, our target text, being typed out by simulated random typing on a standard keyboard. For finding the answer, 30 users randomly typed characters into a file. Then, the frequency of each characters occurred following the previous character is calculated. This conditional probability is used to build the Markov
matrix by considering all 128 times 128 cases. Finally, the expected time we estimated is about 10 to the power of 34 (min), which is surprisingly lower than the theoretical computation, and not achievable at all even in the
cosmic time.
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Applied Physics · Cross-listed from quant-ph
Vector magnetometry using cavity-enhanced microwave readout in nitrogen-vacancy diamond
Reginald Wilcox, David Phillips, Matthew Steinecker et al. (+6 more)
We demonstrate $4\pi$-steradian vector
magnetic field sensing using an ensemble of nitrogen-vacancy (NV) centers in a single-
crystal diamond coupled to a microwave (MW) cavity. The MW cavity enhances the
spin-
photon coupling which enables efficient, high-contrast
spin-state readout via MW interrogation and removes the need for bulky optical collection components. An applied AC bias
magnetic field lifts the zero-field degeneracy of the four crystallographic NV orientations, allowing each orientation to be individually addressed and used for vector reconstruction of the
magnetic field. The resulting magnetometer has a 40% contrast (20x higher than typical for optical
spin-ensemble readout) and achieves a single-axis sensitivity of 250 pT/$\sqrt{\mathrm{Hz}}$ which is flat from DC to 1 kHz. Noise models of the composite
spin-cavity system establish MW amplitude noise as the dominant noise source and predict a thermal noise limit of 2 pT/$\sqrt{\mathrm{Hz}}$.
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All authors Reginald Wilcox, David Phillips, Matthew Steinecker, Erik Eisenach, Corey Hawkins, Linh Pham, Jennifer Schloss, Dirk Englund, Danielle Braje
Fluid Dynamics
Complex-Potential Analysis of a Slit Model in Electrowetting
Dhairya Shah, Yuan Liu and Samuel Brzezicki
This study develops a complex-potential framework for the electric field near the Triple Contact Point in electrowetting. A global slit model provides the electrostatic potential, surface-charge structure and endpoint expansion. The resulting solution also gives an analytical approximation to the droplet shape and exhibits the characteristic edge singularity of the zero-contact-angle slit model.
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Computational Physics · Cross-listed from cs.DC
Beyond Exascale: Dataflow Domain Translation on a Cerebras Cluster
Tomas Oppelstrup, Nicholas Giamblanco, Delyan Z. Kalchev et al. (+5 more)
Simulation of physical systems is essential across scientific and engineering domains. Commonly used domain decomposition methods are unable to simultaneously deliver both high simulation rate and high utilization in network computing environments. In particular, Exascale systems deliver only a small fraction their peak performance for these workloads. This paper introduces the novel Domain Translation
algorithm, designed to overcome these limitations. On a cluster of 64 Cerebras CS-3 systems, we use this method to demonstrate unprecedented cluster performance across a range of metrics: we show simulations running in excess of 1.6 million time steps per second; we also demonstrate perfect weak scaling at 88% of peak performance. At this cluster scale, our implementation provides 112 PFLOP/s in a power-unconstrained environment, and 57 GFLOP/J in a power-limited environment. We illustrate the method by applying the shallow-water equations to model a tsunami following an asteroid impact at 460m-resolution on a planetary scale.
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All authors Tomas Oppelstrup, Nicholas Giamblanco, Delyan Z. Kalchev, Ilya Sharapov, Mark Taylor, Dirk Van Essendelft, Sivasankaran Rajamanickam, Michael James
Optics · Cross-listed from quant-ph
Efficient computation of quantum time-optimal control
Andrei A. Stepanenko, Kseniia S. Chernova, Maxim Mazanov et al. (+1 more)
We present an approach to compute time-optimal control of a
quantum system which combines
quantum brachistochrone and Lax pair techniques and enables efficient investigation of large-scale
quantum systems. We illustrate our method by finding the
quantum speed limit for a single-particle excitation in a nearest-neighbor-coupled
qubit lattice with switchable couplings and fixed sum of their squares. We obtain the solution for a finite system with up to 10 000
qubits and for the effectively infinite
lattice closed into ring. As another application of our method, we derive the
quantum speed limit for a
lattice with time-independent couplings.
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All authors Andrei A. Stepanenko, Kseniia S. Chernova, Maxim Mazanov, Maxim A. Gorlach
Optics
Charged-particle control via spatio-temporally tailored pulses from gas-based nonlinear optics
Hao Zhang, Joshua Mann, James Rosenzweig et al. (+2 more)
Gas-filled waveguides enable few-cycle, spatio-temporally coupled (STC) pulses with programmable structure, opening new routes to control charged particles with optical fields. This review maps the landscape of optical-field-driven photoemission, then surveys gas-based nonlinear drivers, photonic
crystal fibers (PCFs) for low-energy, high-repetition operation and hollow-core capillaries (HCCs) for high-power, few-cycle synthesis. We highlight mechanisms for deterministic pulse shaping, including four-wave-mixing-based spectral-phase transfer in HCCs, and show how tailored STC waveforms steer emission dynamics from the multiphoton to tunneling regimes, enabling sub-cycle gating, momentum control, and brightness scaling. We conclude with open challenges: phase stability, mid-IR scalability, coupling to nanophotonic emitters, metrology of vectorial fields, and outline a path toward compact, ultrafast, phase-coherent electron sources and emerging
quantum applications powered by nonlinear photonics.
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All authors Hao Zhang, Joshua Mann, James Rosenzweig, Michael Chini, Sergio Carbajo
Applied Physics · Cross-listed from quant-ph
Photonic-integrated quantum sensor array for microscale magnetic localisation
Hao-Cheng Weng, John G. Rarity, Krishna C. Balram et al. (+1 more)
Nitrogen-vacancy centres (NVs) are promising solid-state nanoscale
quantum sensors for applications ranging from material science to biotechnology. Using multiple sensors simultaneously offers advantages for probing spatiotemporal correlations of fluctuating fields or the dynamics of point defects. In this work, by integrating NVs with foundry silicon-nitride photonic integrated
circuits, we realise the scalable operation of eight localised NV sensors in an array, with simultaneous, distinct readout of the individual sensors. Using the eight NV sensors and machine-learning methods for multi-point
magnetic field reconstruction, we demonstrate microscale
magnetic localisation of a 30 $\mu$m-sized needle tip. Experimentally, the needle tip can be localised with an error below its dimension and tracked dynamically with high fidelity. We further simulate the feasibility of our platform for monitoring the position and orientation of
magnetic microrobots designed for biological and clinical purposes. Without the complexity of bulk optics, our photonic-integrated multi-sensor platform presents a step towards real-life biomedical applications under out-of-the-lab conditions.
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All authors Hao-Cheng Weng, John G. Rarity, Krishna C. Balram, Joe A. Smith
Computational Physics
Jay Shen, Yifeng Tang and Andrew Ferguson
Transformers are the go-to architecture for most data modalities due to their scalability. While they have been applied extensively to molecular property prediction, they do not dominate the field as they do elsewhere. One cause may be the lack of structural biases that effectively capture the relationships between atoms. Here, we investigate
attention biases as a simple and natural way to encode structure. Motivated by physical power laws, we propose a family of low-complexity
attention biases $b_{ij} = p \log|| \mathbf{r}_i - \mathbf{r}_j||$ which weigh
attention probabilities according to interatomic distances. On the QM9 and SPICE
datasets, this approach outperforms positional encodings and graph
attention while remaining competitive with more complex Gaussian kernel biases. We also show that good
attention biases can compensate for a complete ablation of scaled dot-product
attention, suggesting a low-cost path toward interpretable molecular
transformers.
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Fluid Dynamics
Laminar boundary layers over small-scale textured surfaces
Samuel D. Tomlinson and Demetrios T. Papageorgiou
We develop a model for steady, laminar boundary layers over small-scale textured surfaces. Although the texture is small relative to the boundary-layer thickness, it modifies the flow via a slip length. We use matched asymptotic expansions to simplify the problem, dividing the flow into outer, boundary-layer and inner regions. The far-field behaviour of the inner problem yields a slip boundary condition for the boundary layer. We derive an asymptotic solution valid when the slip length is small. For arbitrary slip lengths, we develop a numerical method combining Chebyshev collocation and finite differences. We apply this framework to canonical small-scale textured surfaces, including superhydrophobic surfaces and riblets, and utilise existing analytical slip formulae. However, the framework is expected to extend to
liquid-infused, porous, compliant or deformable surfaces with a variety of regular or random textures. We demonstrate how slip modifies the boundary layer's velocity field, wall shear stress and displacement thickness across a range of surface configurations, and examine the linear stability of the resulting slip-modified boundary layers. Our approach enables computationally inexpensive modelling of a wide range of small-scale textured surfaces within laminar boundary-layer flows, providing predictive capability for drag, boundary-layer growth and transition across applications ranging from microfluidics to turbo-machinery and marine transport.
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Optics
Lattice Resonances in Periodic Arrays of Time-Modulated Scatterers
María Blanco de Paz, Juan R. Deop-Ruano, Diego M. Solís et al. (+1 more)
Lattice resonances are collective optical modes supported by periodic arrays of scatterers, arising from their coherent interaction enabled by the underlying periodicity. Owing to their collective nature, these resonances produce optical responses that are both stronger and spectrally narrower than those of individual scatterers. While such phenomena have been extensively studied in conventional time-invariant systems, recent advances in time-varying photonics present new opportunities to exploit and enhance the extraordinary characteristics of these collective modes. Here, we investigate
lattice resonances in periodic arrays of time-modulated scatterers using a simple framework based on the dipolar approximation and time-Floquet theory, where each scatterer is modeled as a harmonic oscillator with periodically varying optical properties. We begin by analyzing the response of an individual scatterer, leveraging our model to identify the complex eigenfrequencies that define its dynamics. We show that, for the appropriate modulation amplitude and frequency, the imaginary part of one of these eigenfrequencies vanishes, leading to amplification. Building on this, we extend our analysis to a periodic array to investigate the effect of the interplay between temporal modulation and
lattice resonances. In contrast to isolated scatterers, the collective nature of
lattice resonances introduces a markedly more intricate spectral dependence of the amplification regime. Notably, this amplification emerges at substantially lower modulation strengths, facilitated by the enhanced light-matter interaction and increased lifetime provided by these collective resonances. Our work establishes a simple theoretical framework for understanding collective
lattice resonances in time-modulated arrays, enabling dynamic control and amplification of these modes.
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All authors María Blanco de Paz, Juan R. Deop-Ruano, Diego M. Solís, Alejandro Manjavacas
Fluid Dynamics
Influence of Rotation on Fingering Convection in Planetary Cores
Martin Gray, Celine Guervilly and Graeme Sarson
Stably stratified layers are thought to develop at the top of the
liquid metallic cores of many terrestrial
planets. We consider the case where the thermal gradient is stable but the compositional gradient is unstable, a situation particularly relevant to Mercury. The strong contrast between molecular diffusivities of temperature and composition leads to fingering convection. We investigate this process using hydrodynamical simulations in a rotating spherical shell, systematically varying the stratification strength N relative to the rotation rate $\Omega$. In all regimes, the primary fingering mode forms narrow, elongated structures that shift orientation from the rotation axis to the direction of
gravity as $N^2/\Omega^2$ exceeds 10. The fingers remain laminar, with transverse scales proportional to thermal stratification but independent of rotation. Fingering convection also drives secondary large-scale flows across most of the explored parameter space, producing diverse dynamics including zonal flows, hemispherical convection, axisymmetric poloidal bands, finger clusters, and toroidal gyres. In the rapidly-rotating regime, laterally inhomogeneous mixing generates zonal flows in thermo-compositional wind balance; zonal flow direction and amplitude depend on $N^2/\Omega^2$, with amplitude weakening for strong stratification $N^2/\Omega^2>10$. In the intermediate regime ($N^2/\Omega^2\sim 1$), axisymmetric or spiraling poloidal bands emerge within the tangent cylinder, gradually overtaking the primary fingers. For stronger stratification, finger clusters and weak, large-scale density anomalies surrounded by toroidal gyres form in the upper domain. These diverse large-scale flows may interact with the dynamo-generated
magnetic field in the deeper core, potentially influencing surface
magnetic fields.
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Applied Physics
Multi-wavelength transparent microfluidics for UV-visible spectroscopy and X-ray scattering studies of photoactive systems
Benedetta Marmiroli, Sumea Klokic, Barbara Sartori et al. (+3 more)
Microfluidic devices are increasingly used in synchrotron-based experiments to deliver and probe
liquid samples, offering advantages such as minimal sample consumption and reduced radiation damage. Despite their growing use, few devices have been specifically designed for monitoring
liquids under photoexcitation, a promising approach for fast structural transitions. Here, a microfluidic device that is transparent to X-rays in one direction, and simulaneously transmits UV and visible light in the perpendicular direction is presented. The device is fabricated using lamination and UV lithography on a dry-film resist, eliminating the need for cleanroom facilities and simplifying production. Its multi-wavelength transparency was validated through UV-visible spectroscopy, where photoexcitation at different wavelengths induced reversible trans-to-cis isomerization of azobenzene and fluoro-azobenzene. X-ray transparency was validated through Small Angle X-ray Scattering (SAXS) measurements on hemoglobin and CO-ligated hemoglobin sensitive to quaternary structural changes. These resusts confirm the suitability of the device for resolving
protein structures and photoinduced conformational dynamics. The design further supports, as some proof of concept results show, temperature-jump and time resolved pump-probe experiments, providing a versatile platform for studying structural
evolution in
liquid samples using synchrotron SAXS.
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All authors Benedetta Marmiroli, Sumea Klokic, Barbara Sartori, Marie Reissenbuechel, Alessio Turchet, Heinz Amenitsch
Fluid Dynamics
Nonlinear Unsteady Vortex-Lattice Vortex-Particle Method with Adaptive Wake Conversion for Rotorcraft Aerodynamics
Jinbin Fu and Eric Laurendeau
Nonlinear unsteady
vortex lattice-
vortex particle methods (NL-UVLM-VPM) provide medium-fidelity predictions of rotorcraft aerodynamics with explicit three-dimensional wake representations at a moderate computational cost. This study presents an NL-UVLM-VPM approach with a scale-consistent adaptive wake panel-particle conversion strategy that mitigates the inherent temporal-spatial resolution coupling of conventional wake treatments in rotorcraft aerodynamic simulations. Numerical assessment shows that this strategy preserves the near third-order temporal convergence of the underlying time-integration scheme while improving robustness under coarsened temporal resolution. For a representative hover case, computational time is reduced by 29% relative to the conventional conversion strategy at identical temporal resolution and by nearly 70% compared with a fine-resolution reference simulation over 20 rotor revolutions, while maintaining thrust and torque predictions within 1% of the reference solution. Based on these analyzes, practical recommendations for particle conversion parameters and wake resolution are provided. The methodology is further validated for increasingly complex scenarios, including hover, forward flight with blade-
vortex interaction, and multirotor interaction. Predictions show good agreement with experimental data and dedicated unsteady Reynolds-averaged Navier-Stokes simulations (URANS), while computational speedups exceeding two orders of magnitude relative to URANS are achieved.
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Fluid Dynamics
Vortex breakdown and its topologies in turbulent flows within a typical swirl combustor geometry
Nitesh Kumar Sahu, Anupam Dewan and Mayank Kumar
We investigate
vortex breakdown (VB) and its dominant
topologies in turbulent, non-reacting flows within a canonical swirl combustor using large-eddy simulations (LES). A baseline configuration and operating conditions are first used to validate the LES solver, then five additional cases differing only by swirler vane-angle are simulated. The onset of VB is quantified using the generic swirl-number formulation, SNg, by detecting an internal recirculation zone (IRZ) in the mean flow, excluding highly-intermittent VB cases. Analysis of the mean flow shows that SNg measured within 40 mm downstream of swirler best represents the flow's swirl-strength compared with commonly used alternatives. A stable-VB first appears in the flow with 25{\deg} vane-angle, SNg=0.35. Q-criterion iso-surfaces and velocity time-series at VC footprints show a single-helix VC to prevail across all investigated vane-angles; up to 60{\deg}, SNg=0.98. Weaker double-helix signatures also appear, resulting from quadratic self-interaction of single-helix tone for vane-angles <= 50{\deg}. They are quadratically independent in 60{\deg} case, indicating association with a distinct helical hydrodynamic mode. Axisymmetric IRZ oscillations interact with helical-VC dynamics in 25{\deg} and 60{\deg} cases. VC precesses as stable limit-cycle oscillation via a marginally stable mode in 40{\deg} to 50{\deg} cases, while it waxes and wanes strongly in 25{\deg} and 60{\deg} cases driven by
stochastic forcing of a slightly stable mode. Alongside the coherent VC-strand, a weakly-coherent strand originates from swirler. Its precession frequency matches with the lowest coherent precession frequency, corroborating its precession-based origin. Overall, we establish critical-values, evaluation locations and a
topology-map for predicting and interpreting VB-states in isothermal swirl combustor flows.
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Computational Physics · Cross-listed from cs.LG
Differentiation Strategies for Acoustic Inverse Problems: Admittance Estimation and Shape Optimization
Nikolas Borrel-Jensen and Josiah Bjorgaard
We demonstrate a practical differentiable programming approach for acoustic inverse problems through two applications: admittance estimation and shape optimization for resonance damping. First, we show that JAX-FEM's automatic differentiation (AD) enables direct gradient-based estimation of complex boundary admittance from sparse pressure measurements, achieving 3-digit precision without requiring manual derivation of adjoint equations. Second, we apply randomized finite differences to acoustic shape optimization, combining JAX-FEM for forward simulation with PyTorch3D for mesh manipulation through AD. By separating physics-driven boundary optimization from geometry-driven interior mesh adaptation, we achieve 48.1% energy reduction at target frequencies with 30-fold fewer FEM solutions compared to standard finite difference on the full mesh. This work showcases how modern differentiable software stacks enable rapid prototyping of optimization workflows for physics-based inverse problems, with automatic differentiation for parameter estimation and a combination of finite differences and AD for
geometric design.
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Optics · Cross-listed from quant-ph
Bidimensional measurements of photon statistics within a multimodal temporal framework
C. Hainaut, K. Ouahrouche, A. Rancon et al. (+5 more)
Ultrafast imaging of
photon statistics in two dimensions is a powerful tool for probing non-
equilibrium and transient optical phenomena, yet it remains experimentally challenging due to the simultaneous need for high temporal resolution and statistical fidelity. In this work, we demonstrate spatially resolved single-shot measurements of
photon number distributions using difference-frequency generation (DFG) in a nonlinear BBO
crystal. We show that our platform can discriminate between coherent and thermal
photon statistics across two spatial dimensions with picosecond resolution. At the same time, we find that the retrieved distributions deviate from the ideal ones, a consequence of
vacuum contamination and the
multimodal response of the amplifier. To explain this, we develop a temporal mode decomposition framework that captures the essential physics of signal amplification and fluorescence, and quantitatively reproduces the experimental findings. This establishes a robust approach for measuring two-dimensional
photon statistics while clarifying the fundamental factors that limit the fidelity of such measurements.
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All authors C. Hainaut, K. Ouahrouche, A. Rancon, G. Patera, C. Ouarkoub, M. Le Parquier, P. Suret, A. Amo
Instrumentation and Detectors
GRANITE: High-Resolution Imaging and Electrical Qualification of Large-Area TPC Electrodes
Shumit A. Mitra, Alexander Deisting, Jan Lommler et al. (+4 more)
Next-generation dual-phase time projection chambers (TPCs) for rare event searches will require large-scale, high-precision electrodes. To meet the stringent requirements for high-voltage performance of such an experiment, we have developed a scanning setup for comprehensive electrode quality assurance. The system is built around the GRANITE (Granular Robotic Assay for Novel Integrated TPC Electrodes) facility: a gantry
robot on top of a $2.5\,\text{m}\times1.8\,\text{m}$ granite table, equipped with a suite of non-contact metrology devices. We developed a coaxial wire scanning head to measure and correlate localized high-voltage discharge currents in air with high-resolution surface images. We find that the identified discharge 'hotspots' are transient and show no significant correlation with static visual features. Next, we established a quantitative relationship between artificially induced abrasive surface damage on the wires and a reduction in the discharge inception voltage. This work provides a novel non-invasive tool for qualifying wires dedicated for use in electrodes for future low-background experiments.
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All authors Shumit A. Mitra, Alexander Deisting, Jan Lommler, Uwe Oberlack, Fabian Piermaier, Quirin Weitzel, Daniel Wenz
Instrumentation and Detectors
GRANITE: Mechanical Characterization and Optical Inspection of Large-Area TPC Electrodes
Alexander Deisting, Jan Lommler, Shumit A. Mitra et al. (+4 more)
Next-generation dual-phase time projection chambers (TPCs) for rare event searches will require large-scale, high-precision electrodes. To meet the stringent requirements for mechanical stability and high-voltage performance of such an experiment, we have developed a scanning setup for electrode quality assurance called GRANITE: Granular Robotic Assay for Novel Integrated TPC Electrodes. GRANITE is built around a gantry
robot on top of a $2.5\,\text{m}\times1.8\,\text{m}$ granite table, equipped with a suite of non-contact metrology devices. We demonstrate the setup's capabilities in two key areas: first, using
laser scanners, we characterize wire tension, and in an independent measurement wire deflection due to
gravity and electrostatic forces is determined. The setup achieves a precision of $20\,\mu\text{m}$ for the relative measurement of only electrostatic displacement. Furthermore, GRANITE can measure gravitational sag down to $200\,\mu\text{m}$ in an absolute measurement; this precision improves to $50\,\mu\text{m}$ when applying model-based corrections for systematic effects. The performance achieved exceeds the needs for the characterisation of the electrode sagging in future experiments, which typically aims to ensure a maximal sag on the order of $500\,\mu\text{m}$. Second, we use GRANITE's high resolution camera to image all wires of XENON1T's cathode grid. Subsets of these images are then hand sorted and used to train an autoencoder, to reliably classify wire images as either pristine wires or images containing severe anomalous features. These anomalies appear e.g. as staining and may be potential defects. The interpretation of the classification results is complicated by the fact that most wire segments are not spotless, but show a varying amount of anomalous features. Follow-up studies are needed to identify the exact nature of such features on wires.
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All authors Alexander Deisting, Jan Lommler, Shumit A. Mitra, Uwe Oberlack, Fabian Piermaier, Quirin Weitzel, Daniel Wenz