Instrumentation and Detectors
A journey to ITACA: Ion Tracking with Ammonium Cations Apparatus
J. J. Gómez-Cadenas, L. Arazi, M. Elorza et al. (+6 more)
A unique feature of gas xenon electroluminescent time projection chambers (GXeEL TPCs) in $0\nu\beta\beta$ searches is their ability to reconstruct event
topology, in particular to distinguish "single-electron" from "double-electron" tracks, the latter being the signature of a $0\nu\beta\beta$ decay near the decay endpoint $Q_{\beta\beta}$. Together with excellent energy resolution and the t$_0$ provided by primary scintillation, this topological information is key to suppressing backgrounds. Preserving EL, however, requires operation in pure xenon (with helium as the only benign additive), where electron
diffusion is large. Consequently, reconstructed track fidelity is limited by
diffusion and intrinsic EL blurring. We propose augmenting the detector with the ability to image not only the electron track but also the corresponding mirror ion track. Introducing trace amounts of NH$_3$ ($\sim$100 ppb) converts primary xenon ions into ammonium ions, NH$_4^+$, via a fast two-step ion-molecule process involving charge transfer followed by
proton transfer, while leaving EL unaffected. Electrons drift rapidly to the anode, producing the standard EL image, whereas NH$_4^+$ ions drift slowly toward the cathode, allowing time to determine the event energy and barycenter. For events in the region of interest, an ion sensor near the cathode at the projected barycenter captures the ions.
Laser interrogation of the sensor's molecular layer then reveals an ion-track image with sub-millimeter
diffusion and no EL-induced smearing. Combined electron-ion imaging strengthens topological discrimination, improving background rejection by about an order of magnitude and significantly extending the discovery potential of GXeEL TPCs for very long $0\nu\beta\beta$ lifetimes.
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All authors J. J. Gómez-Cadenas, L. Arazi, M. Elorza, Z. Freixa, F. Monrabal, A. Pazos, J. Renner, S.R. Soleti, S. Torelli
Optics
Polarization Dependent Enhancement of Magnetic Dipolar Emission with Silicon Nanodimers
Marijn Rikers, Ayesheh Bashiri, Aleksandr Vaskin et al. (+5 more)
Eu(TTA)3 complexes are used as an emission source in the presence of high refractive index dielectric nanostructures. These nanostructures support Mie-type resonances that modify the local density of optical states. Specifically, the silicon dimer provides polarization-dependent electric and
magnetic field enhancement in the dimer gap to modify the electric dipolar and
magnetic dipolar emissions of the Eu3+ at 610 nm and 590 nm, respectively. Finite element method simulations are used to determine the optimal parameters for the sample and to demonstrate the polarization-dependent emission enhancement of dipolar emitters in the gap. A two-step electron beam lithography process is used to fabricate the hybrid nanoscopic structures, with a Eu3+ doped electron beam resist located only in the center of the dimer. The results demonstrate the potential of these nanostructures to selectively tailor the emission of the two distinct dipolar transitions by engineering the resonant nanostructures. Our work highlights the potential of
magnetic light-matter interactions as a novel degree of freedom.
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All authors Marijn Rikers, Ayesheh Bashiri, Aleksandr Vaskin, Ángela Barreda, Duk-Yong Choi, Michael Steinert, Thomas Pertsch, Isabelle Staude
Optics · Cross-listed from quant-ph
Tunable passive squeezing of squeezed light through unbalanced double homodyne detection
Niels Tripier-Mondancin, David Barral, Ganaël Roeland et al. (+3 more)
The full characterization of
quantum states of light is a central task in
quantum optics and information science. Double homodyne detection provides a powerful method for the direct measurement of the Husimi Q quasi-probability distribution, offering a complete state representation in a simple experimental setting and a limited time frame. Here, we demonstrate that double homodyne detection can serve as more than a passive characterization tool. By intentionally unbalancing the input beamsplitter that splits the
quantum signal, we show that the detection scheme itself performs an effective squeezing or anti-squeezing transformation on the state being measured. The resulting measurement directly samples the Q function of the input state as if it were acted upon by a squeezing operator whose strength is a tunable experimental parameter: the beamsplitter's reflectivity. We experimentally realize this technique using a robust polarization-encoded double homodyne detection to characterize a squeezed
vacuum state. Our results demonstrate the controlled deformation of the measured Q function's phase-space distribution, confirming that unbalanced double homodyne detection is a versatile tool for simultaneous
quantum state manipulation and characterization.
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All authors Niels Tripier-Mondancin, David Barral, Ganaël Roeland, Raúl Leonardo Rincon Celis, Yann Bouchereau, Nicolas Treps
Optics
Laser-pumped drilling carbon nanotube vortex shock waves in optical fibers
Ricardo E. da Silva and Marcos A. R. Franco
We experimentally demonstrate
laser-induced
vortex shock waves formed by carbon nanotubes drilling optical fibers for the first time. Three samples of standard single-mode optical fibers (SMF) are sequentially inserted in a syringe loaded with a 1 mL solution of single-walled carbon nanotubes (CNT) and methanol, and a high-power
laser is injected into the fibers for 5 (SMF 1), 10 (SMF 2), and 20 (SMF 3) minutes. The CNT solution thermally expands and generates
vortex acoustic flows, which are confined in the syringe cavity, significantly increasing the velocity and impact of nanotubes at the fiber tip. The resulting shock waves achieve estimated hypersonic velocities (5742 m/s) and high pressures (6.7 GPa), overcoming the silica tensile strength and ablating structured
vortices in the fibers. The material, geometry, and depth profile of the
vortices are characterized, providing details of mixing carbon and silica layers, increasing radially from the fiber core center and in thickness to the cladding for longer
laser periods (850 nm to 10 micron thickness). The cross-sections of the measured
vortices are compared to analytical simulations, revealing unprecedented Fibonacci helices drilling holes in the fiber core with a 5 micron maximum depth, while depositing nanoscale CNT-silica layers following Fibonacci spirals. These achievements point out a new route for
laser-controlled deposition of nanoparticles and fabrication of
vortex devices on fiber tips, which is promising for all-fiber
vortex spatial phase modulators in optical communications, fiber sensors, high-power pulsed fiber
lasers, and biomedical ultrasonic neurotransmitters.
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Biological Physics
Data-Efficient Learning of Anomalous Diffusion with Wavelet Representations: Enabling Direct Learning from Experimental Trajectories
Gongyi Wang, Yu Zhang and Zihan Huang
Machine learning (ML) has become a versatile tool for analyzing anomalous
diffusion trajectories, yet most existing pipelines are trained on large collections of simulated data. In contrast, experimental trajectories, such as those from single-particle tracking (SPT), are typically scarce and may differ substantially from the idealized models used for simulation, leading to degradation or even breakdown of performance when ML methods are applied to real data. To address this mismatch, we introduce a wavelet-based representation of anomalous
diffusion that enables data-efficient learning directly from experimental recordings. This representation is constructed by applying six complementary wavelet families to each trajectory and combining the resulting wavelet modulus scalograms. We first evaluate the wavelet representation on simulated trajectories from the andi-
datasets benchmark, where it clearly outperforms both feature-based and trajectory-based methods with as few as 1000 training trajectories and still retains an advantage on large training sets. We then use this representation to learn directly from experimental SPT trajectories of fluorescent beads diffusing in F-actin networks, where the wavelet representation remains superior to existing alternatives for both
diffusion-exponent regression and mesh-size classification. In particular, when predicting the
diffusion exponents of experimental trajectories, a model trained on 1200 experimental tracks using the wavelet representation achieves significantly lower errors than state-of-the-art deep learning models trained purely on $10^6$ simulated trajectories. We associate this data efficiency with the emergence of distinct scale fingerprints disentangling underlying
diffusion mechanisms in the wavelet spectra.
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Instrumentation and Detectors
Angular emission of scintillators for nuclear fusion diagnostics
M. Rodríguez-Ramos, J. García-Lópeza, M. Videla-Trevina et al. (+3 more)
Accurate characterization of fast-ion behavior is essential for the safe and efficient operation of
nuclear fusion
plasmas, as energetic particle losses can degrade
plasma performance and damage reactor components. Scintillator-based detectors are widely employed to monitor fast ions; however, existing studies often assume isotropic light emission, neglecting potential angular dependencies that can compromise the determination of ion fluxes. In this work, we investigate the angular emission properties of two commercial scintillators, TG-Green and b-SiAlON, under irradiation with 3.5 MeV He++ and 1 MeV D+ beams, representative of conditions in future fusion devices such as ITER. A novel experimental setup, combining precise optical
alignment, angular scanning, and rigorous calibration, was developed to measure the detection efficiency as a function of observation angle. Prior to the characterization, stability tests demonstrated negligible radiation-induced degradation under the applied fluences, and transmission losses due to optical fiber bending were found to be below 1.5%. The results reveal a pronounced angular anisotropy in scintillation emission for both materials, with intensity decreasing as the detection angle increases, well described by an empirical cosine-based model. Additionally, the normalized response shows minimal dependence on ion species or energy. These findings improve scintillator-based diagnostics, allowing more accurate measurement of fast-ion fluxes in fusion
plasmas.
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All authors M. Rodríguez-Ramos, J. García-Lópeza, M. Videla-Trevina, J. González-Martinc, P. Alvarez-Fraub, M. Kocan
Data Analysis and Statistics · Cross-listed from cond-mat.mes-hall
Single-Particle X-ray Scattering Reveals a High Local Supersaturation of Precursors as the Origin of CoO Assembly Formation
Sani Y. Harouna-Mayer, Lars Klemeyer, Cecilia A. Zito et al. (+24 more)
Single-particle small-angle X-ray scattering (SP-SAXS) enables quantitative morphological analysis by recording diffraction snapshots from isolated particles using X-ray free-electron
laser (XFEL) pulses. Unlike conventional X-ray techniques, which average over the entire illuminated sample volume, SP-SAXS resolves low-contrast, less abundant, or transient species within heterogeneous particle populations that would otherwise remain hidden. Here, we apply SP-SAXS to investigate the solvothermal formation of CoO nanocrystal assemblies from a Co(acac)$_3$ precursor in benzyl alcohol. The single-particle data reveal amorphous, uniform-density Co(acac)$_2$ spheres as transient intermediates that directly crystallize into cavernous CoO nanocrystal assemblies, which explains why CoO forms as hierarchical aggregates rather than as isolated nanocrystals. These results demonstrate that SP-SAXS provides a powerful framework for disentangling morphological heterogeneity in nanoparticle formation processes.
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All authors Sani Y. Harouna-Mayer, Lars Klemeyer, Cecilia A. Zito, Johan Bielecki, Xuemei Cheng, Davide Derelli, Armando D. Estillore, Tjark L.R. Groene, Lukas V. Haas, Romain Letrun, Chan Kim, Jayanath C.P. Koliyadu, Abhishek Mall, Parichita Mazumder, Diogo V.M. Melo, Adam R. Round, Amit K. Samanta, Abhisakh Sarma, Zhou Shen, Xiao Sun, Patrik Vagovic, Tamme Wollweber, Richard Bean, Jochen Küpper, Henry N. Chapman, Dorota Koziej, Kartik Ayyer
Fluid Dynamics
Transition in elastic Dean flow: the centre-mode versus hoop-stress pathways
P. S. D. Surya Phani Tej, Ganesh Subramanian and V. Shankar
We analyse the stability of viscoelastic Dean flow (flow of an elastic fluid through a curved two-dimensional channel, driven by an azimuthal pressure gradient) in the absence of fluid inertia. This configuration is well known to exhibit a hoop-stress-driven `purely elastic' instability (referred to henceforth as the hoop-stress mode – `HSM') on account of the base-flow streamline
curvature. The objective of this study is to demonstrate the existence and importance of a distinct elastic instability in this flow configuration, which is not driven by hoop-stresses, but instead is a continuation of a novel `centre-mode' (CM) instability recently identified in rectilinear shear flows. We use both the Oldroyd-B and FENE-P models to map out parameter regimes in the $W\!i$–$\epsilon$–$\beta$ space where the aforementioned instabilities are present. Here, $W\!i$ is a suitably defined Weissenberg number that characterizes fluid elasticity, $\beta$ is the ratio of solvent to total solution viscosity, and $\epsilon$ is the ratio of the gap (channel) width to the radius of
curvature. For FENE-P model, decreasing the finite extensibility parameter $L$ has opposing effects on the HSM and CM instabilities – stabilising the former, but destabilising the latter. In the dilute solution regime ($\beta > 0.95$), and for realistic values of $L \sim O(100)$, corresponding to
polymer molecular weights of $O(10^{5-6})$g/mol, the CM remains the most unstable mode for $\epsilon \leq 0.25$, rendering it potentially relevant to the onset of elastic
turbulence in the flow of such
polymer solutions through curved channels.
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Space Physics · Cross-listed from astro-ph.HE
Photon Dynamics and Collision Risks in Relativistic Spaceflight: A Comparative Study of Methods and Implications
Li Kai Wen and Joao Rodrigues
This dissertation explores the dynamics of relativistic spaceflight, focusing on the risks associated with collisions and
photon interactions as a spacecraft approaches velocities near the speed of light. The study emphasizes two primary collision types: (1) collisions with interstellar
dust and particles, and (2) interactions with
cosmic molecules, specifically hydrogen. Using principles of energy conservation and relativistic mechanics, the energy transfer from these collisions is calculated, showing that even small particles can impart massive energy at relativistic speeds. The dissertation also examines the impact of the
cosmic microwave background (CMB) radiation, particularly its blue-shifting effect at high velocities, which influences
photon interactions with the spacecraft. Additionally, the Schwinger limit, which sets an upper bound on the electromagnetic field strength for sustained relativistic travel, is discussed in the context of
photon-induced pair production. Lastly, advanced
photon interactions, such as Compton scattering, are analyzed for their role in thermal management and spacecraft design. The findings highlight the importance of shielding, thermal regulation, and collision avoidance strategies in the design of spacecraft for interstellar travel, offering insights into the potential challenges and solutions for achieving relativistic spaceflight.
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Accelerator Physics · Cross-listed from quant-ph
Generation of high-OAM ultraviolet twisted light for RF-photoinjector applications
A.S. Dyatlov, D.M. Dolgintsev, V.V. Gerasimov et al. (+7 more)
The generation of relativistic
vortex electron beams via photoemission requires ultraviolet
laser beams with well-controlled orbital angular momentum (OAM) and compatibility with
radio-frequency (RF) photoinjector drive-
laser systems. High-OAM
vortex beams at a wavelength of 266 nm are generated using three fabricated diffractive optical elements integrated into an operational photoinjector beamline: a reflective fork grating, a high-topological-charge spiral phase plate, and binary axicons. The spiral phase plate produces a high-purity Laguerre-Gaussian mode with an OAM of l = 64 and a conversion efficiency of 80%, whereas binary axicons generate low-divergence quasi-Bessel beams forming a superposition of multiple OAM states with a finite OAM bandwidth imposed by their binary phase structure. Fork gratings provide flexible access to lower OAM values and enable robust modal diagnostics. The generated beams are characterized using cylindrical-lens mode conversion and radial intensity analysis, demonstrating practical control of both the OAM content and spectral bandwidth of ultraviolet structured light for accelerator-based applications.
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All authors A.S. Dyatlov, D.M. Dolgintsev, V.V. Gerasimov, V.V. Kobets, V.P. Nazmov, M.A. Nozdrin, A.N. Sergeev, D.S. Shokin, K.E. Yunenko, D.V. Karlovets
Fluid Dynamics
Scalable CFD Simulations in Multi-Billion Voxel Micro-CT Images of Porous Materials Using OpenFOAM on ARCHER2
J.Maes, Gavin J. Pringle and Hannah P. Menke
This study investigates the use of High-Performance Computing (HPC) to simulate flow and transport in ultra-large micro-CT images of porous materials using Computational Fluid Dynamics (CFD). Two distinct rock samples, representative of two different rock formations - Bentheimer sandstone and Estaillades carbonate - are investigated. The Bentheimer sandstone image, with dimensions 1,950x1,950x10,800 voxels at 6 micron resolution, comprising 41 billion voxels, represents a largely homogeneous structure, while the Estaillades carbonate image, at 1,144x1,144x6,000 voxels and 3.9676 micron resolution, amounting to 8 billion voxels, features greater heterogeneity, including micro-porous regions. These images are used for direct CFD simulations with GeoChemFoam, our OpenFOAM-based numerical solver, leveraging the computational resources of the UK supercomputer ARCHER2. One of the key aspects of the study is the use of the Darcy-Brinkman-Stokes approach, for which the solid surface is represented using a volumetric indicator function, rather than a complex mesh. This enables the use of simple Cartesian meshes that can be generated in parallel in an efficient and scalable manner. The study explores both weak and strong scaling through subvolume decomposition, demonstrating that, due to the strong scalability and the computational power of ARCHER2, full-resolution CFD simulations can be carried out without the need for image size reduction. This work illustrates the potential of HPC to perform detailed, full-scale simulations on large, high-resolution micro-CT data. The approach relies on a meshing strategy that leverages simple, parallelisable Cartesian grids derived from volumetric indicator functions, eliminating the need for complex surface-conforming meshes and allowing scalable simulation of flow and transport in geological and engineering applications.
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Geophysics
Trans-Arctic route feasibility on a pan-Arctic grid under bathymetric and sea-ice constraints
Abdella Mohamed and Xiangyu Hu
Climate driven reductions in Arctic sea ice have renewed interest in trans Arctic shipping, but adoption remains limited by basic questions of route feasibility, safety and excess distance. Existing studies mostly compare idealised great circle shortcuts or use full weather routing systems, leaving a gap for simple basin scale diagnostics on realistic bathymetry and sea ice. We develop an offline graph based framework on a 0.5 degree pan Arctic grid that combines GEBCO 2024 bathymetry with a summer 2018 Arctic sea ice reanalysis from the Copernicus Marine Environment Monitoring Service (CMEMS). An A* pathfinding
algorithm is applied to a canonical Europe Asia origin destination pair to quantify route availability and route length inflation relative to a great circle. Enforcing sea only feasibility increases route length by about 10 percent before depth and ice constraints are applied. Depth thresholds representative of under keel clearance (hmin = 20-50 m) remove up to roughly 15 percent of the sea mask but preserve a trans Arctic connection for hmin = 20 m. Summer sea ice exerts a strong seasonal control: continuous ice safe routes emerge only from mid August, with distances inflated by roughly 20-25 percent even in late summer. When depth and ice constraints are imposed jointly, only about 75 percent of sea
cells remain safe and no continuous joint safe trans Arctic route exists in the tested season. The framework provides a basin scale screening tool for Arctic shipping and a baseline for forecast driven, multi objective routing studies.
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Fluid Dynamics
Dynamics of an internally actuated weakly elastic sphere in a general quadratic flow
Shashikant Verma and Navaneeth K. Marath
Internally actuated elastic particles are widely used in biomedical applications. It is imperative to understand the dynamics of such particles in pressure-driven microfluidic devices to manipulate their motion. We analytically examine the dynamics of an internally actuated elastic particle translating in a general unbounded quadratic flow in the inertialess limit. We consider the particle as a compressible weakly elastic sphere, and its motion is controlled by applying an external point force and a point torque at the centre of its undeformed shape. The fluid and the particle are modelled using the Stokes and the Navier elasticity equations, respectively. We use the domain perturbation method to capture the particle deformation. The point force and the point torque are obtained until O($\alpha^2$), assuming $\alpha\ll 1$. Here, $\alpha$ is the measure of the particle elastic strain induced due to the fluid viscous stress. We present the results for the particle motion in a general unbounded quadratic flow. The results are simplified further for the motion along the centreline in the quadratic component of three Poiseuille flows: 1) elliptical Poiseuille, 2) plane Poiseuille, and 3) Hagen-Poiseuille flows. In the general quadratic flow, the point force at O($\alpha$) is aligned with the particle velocity, while the force at O($\alpha^2$) acts at an angle to the velocity. Furthermore, the torque is non-zero due to elastic effects at O($\alpha$) and O($\alpha^2$). For all the three Poiseuille flows, the point force until O($\alpha^2$) is aligned with the particle velocity, while the torque comes as zero.
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Biological Physics · Cross-listed from cond-mat.soft
Many interacting particles in solution. I. Screening-ranged expansions of electrostatic potential and energy
Sergii V. Siryk and Walter Rocchia
We present an analytical many-body formalism for systems of spherical particles carrying arbitrary free charge distributions and interacting in a polarizable electrolyte solution, that we model within the linearized Poisson–Boltzmann framework. Building on the detailed spectral analysis of the associated nonstandard Neumann–Poincaré-type operators developed in our companion study arXiv:2512.08684, we construct exact explicit expansions of the electrostatic potential and energy in ascending orders of Debye screening thereby obtaining systematic "screening-ranged" series for potentials and energies. These screening-ranged expansions provide a unified and tractable description of many-body electrostatics. We demonstrate the versatility of the approach by showing how it generalizes and improves upon both classical and modern methods, enabling rigorous treatment of heterogeneously charged systems (such as Janus particles) and accurate modeling of higher-order phenomena (such as asymmetric dielectric screening, opposite-charge repulsion, like-charge attraction) as well as yielding many-body generalizations to analytical explicit results previously known only in the two-body setting.
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Atomic Physics
A cold beam of BaOH molecules using a water-vapour seeded neon gas
Ties Hendrik Fikkers, Nithesh Balasubramanian, Joost W.F. van Hofslot et al. (+3 more)
In this paper we report on the production and characterization of a cold beam of BaOH molecules using a cryogenic buffer-gas beam source. BaOH is a highly suitable molecule for studies of the violation of fundamental
symmetries, such as the search for the electron's electric dipole moment. BaOH molecules are synthesised inside the cold source through
laser ablation of a barium metal target while water vapor is seeded into the neon buffer gas. The BaOH flux is significantly enhanced ($\sim$11 times) when
laser-exciting the barium atoms inside the buffer-gas
cell on the $^1\mathrm S_0 - ^3\mathrm P_1$ transition. A similar enhancement has been reported for other alkaline-earth(-like) monohydroxides. For typical source conditions, the molecular beam has an average velocity of $\approx180$ m/s and an intensity of $\sim 10^{9}$ molecules s$^{-1}$ in $N=1$, which is comparable to that of cryogenic BaF beams.
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All authors Ties Hendrik Fikkers, Nithesh Balasubramanian, Joost W.F. van Hofslot, Maarten C. Mooij, Hendrick L. Bethlem, Steven Hoekstra
Biological Physics · Cross-listed from quant-ph
Practical protein-pocket hydration-site prediction for drug discovery on a quantum computer
Daniele Loco, Kisa Barkemeyer, Andre R. R. Carvalho et al. (+1 more)
Demonstrating the practical utility of Noisy Intermediate-Scale
Quantum (NISQ) hardware for recurrent tasks in Computer-Aided Drug Discovery is of paramount importance. We tackle this challenge by performing three-dimensional
protein pockets hydration-site prediction on a
quantum computer. Formulating the water placement problem as a Quadratic Unconstrained Binary Optimization (QUBO), we use a hybrid approach coupling a classical three-dimensional reference-interaction site model (3D-RISM) to an efficient
quantum optimization solver, to run various hardware experiments up to 123
qubits. Matching the precision of classical approaches, our results reproduced experimental predictions on real-life
protein-ligand complexes. Furthermore, through a detailed resource estimation analysis, we show that accuracy can be systematically improved with increasing number of
qubits, indicating that full
quantum utility is in reach. Finally, we provide evidence that advantageous situations could be found for systems where classical optimization struggles to provide optimal solutions. The method has potential for assisting simulations of
protein-ligand complexes for drug lead optimization and setup of docking calculations.
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All authors Daniele Loco, Kisa Barkemeyer, Andre R. R. Carvalho, Jean-Philip Piquemal
Instrumentation and Detectors
Development & first Performance evaluation of multi-element monolithic HPGe detector for X-ray spectroscopy
N.Goyal, F.J.Iguaz, S.Aplin et al. (+24 more)
The first operational prototype of a high-purity Germanium (HPGe) detector developed within the European LEAPS-INNOV project is presented in this work. This prototype features a monolithic, multi-element sensor optimized for high-resolution X-ray spectroscopy in the hard X-ray regime, capable of handling high count rates (20-250 kcps/mm2) across a broad energy range (5-100 keV). We discuss here a complete laboratory-based characterization of the detector's performance, as well as an on-beam evaluation at the BM05 beamline of the ESRF synchrotron facility, using monochromatic X-rays in the 20-50 keV energy range. We provide a detailed performance assessment that also includes a phenomenological defect-depth estimation model.
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All authors N.Goyal, F.J.Iguaz, S.Aplin, A.Balerna, P.Bell, J.Casas, M.Cascella, S.Chatterji, C.Cohen, E.Collet, E.N.Gimenez, H.Graafsma, H.Hirsemann, K.Klementiev, T.Kolodziej, T.Martin, R.H.Menk, C.Menneglier, C.Meraihia, J.R.Murias, M.Porro, M.Quispe, B.Schmitt, S.Scully, M.Turcato, C.Ward, E.Welter
Applied Physics · Cross-listed from cond-mat.mes-hall
An extended low-frequency noise compact model for single-layer graphene FETs including correlated mobility fluctuations effect
Nikolaos Mavredakis, Anibal Pacheco-Sanchez and David Jimenez
Correlated mobility fluctuations are considered in the physics-based carrier number fluctuation deltaN low-frequency noise (LFN) compact model of single-layer
graphene field effect transistors (GFET) in the present study. Trapped charge density and Coulomb scattering coefficient deltaN LFN parameters are obtained after applying a parameter extraction methodology, adapted from conventional silicon technologies, to the linear ambipolar regions of GFETs. Appropriate adjustments are considered in the method according to GFETs physical characteristics. Afterwards, Hooge mobility as well as series resistance fluctuations LFN parameters can be extracted. The updated LFN model is validated with experimental data from various long and short-channel GFETs at an extended range of gate and drain bias conditions.
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Optics
Dielectric permittivity tensor dynamics of in-plane hyperbolic van der Waals MoOCl2 and emergent chiral photonic applications
Artsruni Margaryan, Maksim Sargsyan, Meri Hayrapetyan et al. (+3 more)
Van der Waals (vdW)
crystals offer unique opportunities for modern nanophotonic applications owing to their intrinsic anisotropic nature. While most of them exhibit uniaxial anisotropy arising from weak out-of-plane vdW interaction, some of their representative families also exhibit an in-plane biaxial anisotropy. Among the latter, outstand vdW oxochlorides with in-plane axes of a different physical character (metallic or dielectric). Here, we present an accurate dynamics of dielectric permittivity tensor components of vdW MoOCl2 in the ultraviolet (UV) to visible (Vis) spectral region partly covering near-infrared (NIR). Addressing its enormously anisotropic optical constants, we focus on another hyperbolicity window of vdW MoOCl2 emerging in the UV spectral region that may potentially unlock rich light-matter interaction effects. Furthermore, we propose an approach towards designing nanoscale handedness preserved Vis light circular polarizers based on twisted helical vdW MoOCl2
heterostructures. Our findings display that vdW MoOCl2 provides a highly promising platform not only for
hyperbolic, but also for
chiral nanophotonic applications.
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All authors Artsruni Margaryan, Maksim Sargsyan, Meri Hayrapetyan, David Karakhanyan, Kostya S. Novoselov, Davit A. Ghazaryan
Biological Physics
Enzyme-driven phase separation
Damiano Andreghetti, Alfredo Braunstein, Luca Dall'Asta et al. (+1 more)
The formation of polarized signaling domains on
cell membranes is a fundamental example of biological pattern formation. While such patterns resemble structures from
equilibrium phase separation, they are intrinsically non-
equilibrium, driven by energy-consuming enzymatic cycles that switch molecules like phosphoinositides or small GTPases between distinct states. Here, we develop a minimal model of this enzyme-driven phase ordering process. Starting from microscopic reaction kinetics, we derive a mesoscopic theory that belongs to the class of active Model A with a global constraint. This framework yields an explicit mean-field phase diagram and closed-form expressions for key observables, such as interfacial tension, domain fractions, and phase coexistence boundaries, in terms of kinetic rates. In this context, phase coexistence is controlled by non-
equilibrium parameters like catalytic rates and enzymatic asymmetry, rather than
equilibrium parameters such as saturation concentrations. The resulting phase-separated domains rapidly exchange material with their surroundings. Their maintenance requires a continuous power input determined by enzymatic kinetics. The predicted phenomenology is consistent with experimental observations on reconstituted systems of phosphoinositide and Rab5 membrane patterning. We further study how metastable uniform states decay via nucleation of minority-phase domains and subsequent coarsening, driven by an effective interfacial tension. Using large deviation theory, we derive the critical nucleation radius under the action of the intrinsic, multiplicative chemical noise. The analytical results are quantitatively confirmed by
stochastic simulations of the process. Our work provides a theoretical framework identifying key biochemical parameters controlling active phase separation on membrane scaffolds, offering testable predictions for experiments.
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All authors Damiano Andreghetti, Alfredo Braunstein, Luca Dall'Asta, Andrea Gamba
Physics and Society · Cross-listed from q-bio.PE
Joint economic and epidemiological modelling of alternative pandemic response strategies
M J Plank, M Sushames, T Fisher-Taylor et al. (+4 more)
In an emerging pandemic, policymakers need to make important decisions with limited information, for example choosing between a mitigation, suppression or elimination strategy. These strategies may require trade-offs to be made between the health impact of the pandemic and the economic costs of the interventions introduced in response. Mathematical models are a useful tool that can help understand the consequences of alternative policy options on the future dynamics and impact of the epidemic. Most models have focused on direct health impacts, neglecting the economic costs of control measures. Here, we introduce a model framework that captures both health and economic costs. We use this framework to compare the expected aggregate costs of mitigation, suppression and elimination strategies, across a range of different epidemiological and economic parameters. We find that for diseases with low severity, mitigation tends to be the most cost-effective option. For more severe diseases, suppression tends to be most cost effective if the basic reproduction number $R_0$ is relatively low, while elimination tends to be more cost-effective if $R_0$ is high. We use the example of New Zealand's elimination response to the Covid-19 pandemic in 2020 to anchor our framework to a real-world case study. We find that parameter estimates for Covid-19 in New Zealand put it close to or above the threshold at which elimination becomes more cost-effective than mitigation. We conclude that our proposed framework holds promise as a decision-support tool for future pandemic threats, although further work is needed to account for population heterogeneity and other factors relevant to decision-making.
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All authors M J Plank, M Sushames, T Fisher-Taylor, A Afshari, R N Thompson, A Hurford, S C Hendy
Physics and Society
Critical Thresholds in Non-Pharmaceutical Interventions for Epidemic Control
Jinghui Wang, Yutian Zeng, Cong Xu et al. (+7 more)
Non-pharmaceutical interventions, such as contact tracing and social distancing, are critical for controlling epidemic outbreaks, yet their dynamic interactions remain underexplored. We introduce a probabilistic framework to analyze the synergy between contact tracing speed, quantified by the contact tracing period $\tau$, and the average number of close contacts, $\bar{k}_+$, reflecting social distancing measures. We identify critical thresholds ($R=1$) that separate pandemic and contained phases in the $\bar{k}_{+}-\tau$ plane, validated using high-resolution data from Shenzhen's 2022 Omicron outbreak (1,187 cases, 86,451 contacts). Our findings show that contact tracing alone can contain diseases with $R_0 < 2.12$ (95% CI 2.07-2.16), covering 43.33% of major infectious diseases, while combining with social distancing extends control to $R_0 < 7.82$ (95% CI 7.70-7.93), encompassing 86.67% of pathogens. These results, supported by empirical data, highlight the efficacy of rapid tracing and targeted social distancing as alternatives to mass PCR testing. Our framework offers actionable insights for optimizing NPI strategies, though challenges in scaling to regions with higher tracing miss rates or weaker infrastructure underscore the need for adaptive, data-driven policies.
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All authors Jinghui Wang, Yutian Zeng, Cong Xu, Xiyun Zhang, Zhanwei Du, Jiarong Xie, Jiu Zhang, Sen Pei, Zijian Feng, Yanqing Hu
Biological Physics · Cross-listed from cond-mat.soft
Forces at the scale of the cell
K. Vijay Kumar, Mandar M. Inamdar, Pramod A. Pullarkat et al. (+1 more)
The importance of molecular-scale forces in sculpting biological form and function has been acknowledged for more than a century. Accounting for forces in biology is a problem that lies at the intersection of soft condensed matter physics, statistical mechanics, and experimental methods, all adapted to a cellular context. This review surveys how forces arise within the
cell. We provide a summary of the relevant background in
cell biophysics, of soft-matter systems in and out of thermodynamic
equilibrium, and of various force measurement methods. These ideas are then deployed to describe how forces are generated, transmitted, and sensed in specific
cell-scale processes. We emphasize active matter descriptions, methodological tools that provide ways of incorporating non-
equilibrium effects in a systematic manner into conceptual as well as quantitative descriptions. Our examples include polymerization forces, the motion of molecular motors, the properties of the actomyosin cortex, the mechanics of
cell division, and shape changes in tissues. We suggest that a deeper understanding of
cell function will necessarily require integrating the action of
cell-scale physical forces with the assimilation and processing of information.
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All authors K. Vijay Kumar, Mandar M. Inamdar, Pramod A. Pullarkat, Gautam I. Menon
Physics Education
Optics experiments as a tool for developing critical thinking in physics education
Miriam Spodniaková Pfefferová and Martin Plesch
Experimental activities are an essential part of physics education. In addition to conveying scientific knowledge, they play a significant role in developing scientific literacy, inquiry skills, and critical thinking. In today's world, where students are exposed to vast amounts of information of varying quality, the ability to analyse, evaluate, and interpret information correctly has become increasingly important. This paper presents a series of physics experiments in the field of optics, specifically designed to foster critical thinking at various stages of the inquiry process. The topic of optics was chosen deliberately, as many optical phenomena occur naturally in everyday life, are familiar to students, and stimulate their curiosity. At the same time, they provide space for formulating hypotheses, designing experiments, interpreting data, and evaluating alternative explanations. Each experiment begins with a real-life problem situation that students are expected to explore and resolve through their own investigative work. The tasks are structured to encourage discussion, require argumentation, and promote reflection on both the process and the outcomes. The proposed experiments are suitable for students at both primary and secondary school levels and can be implemented in formal as well as non-formal educational settings. The aim of this contribution is to demonstrate how well-designed and pedagogically grounded experiments can not only enhance the understanding of physical concepts but also systematically develop critical thinking skills - one of the key competencies of 21st-century education.
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Plasma Physics
Photon Phase-Space Dynamics in a Plasma Wakefield Accelerator
Neil Beri, John Palastro, Qian Qian et al. (+3 more)
Frequency up-shifting of
laser light in a beam-driven
plasma wakefield has the potential to provide high-intensity sources of short wavelength radiation. Simulations have demonstrated that a
laser pulse can undergo large frequency shifts, limited only by the drive beam energy, when the
plasma density is tailored to match the accelerating phase of the wake to the group velocity of the pulse. Here, we study the dynamical
evolution of
photons in the phase-space vicinity of the
plasma wake-phase matching condition. Numerical calculations using a
photon kinetic model are validated by direct comparison with full electromagnetic particle-in-
cell simulations. These calculations form the basis of a linear theory of the
photon dynamics which reveals several important results, including scalings for the properties of the witness pulse and a self-similar solution for the
photon phase-space dynamics. One prediction of the theory is that the pulse can be compressed indefinitely with no lower bound on the duration. This predication suggests that
photon acceleration can provide a novel source of sub-femtosecond, short wavelength radiation.
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All authors Neil Beri, John Palastro, Qian Qian, Kyle Miller, Brandon Russell, Alexander Thomas
Classical Physics
Rigid body kinematics in an intuitive group-theoretic approach, as completely as possible: Part I Rotational phenomena
Ziyuan Wang
This paper focuses on rotational phenomena of rigid body kinematics. It discusses them in a group-theoretic approach as completely as possible, using methods and notations as intuitive as possible. With a review of current literature, this article also covers some original parts that remain largely unexplored.
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Geophysics
Self-Reinforced Deep Priors for Reparameterized Full Waveform Inversion
Guangyuan Zou, Junlun Li, Feng Liu et al. (+3 more)
Full waveform inversion (FWI) has become a widely adopted technique for high-resolution subsurface imaging. However, its inherent strong nonlinearity often results in convergence toward local minima. Recently, deep image prior-based reparameterized FWI (DIP-FWI) has been proposed to alleviate the dependence on massive training data. By exploiting the spectral bias and implicit regularization in the neural network architecture, DIP-FWI can effectively avoid local minima and reconstruct more geologically plausible velocity models. Nevertheless, existing DIP-FWI typically use a fixed random input throughout the inversion process, which fails to utilize the mapping and correlation between the input and output of the network. Moreover, under complex geological conditions, the lack of informative prior in the input can exacerbate the ill-posedness of the inverse problem, leading to artifacts and unstable reconstructions. To address these limitations, we propose a self-reinforced DIP-FWI (SRDIP-FWI) framework, in which a steering
algorithm alternately updates both the network parameters and the input at each iteration using feedback from the current network output. This design allows adaptive structural enhancement and improved regularization, thereby effectively mitigating the ill-posedness in FWI. Additionally, we analyze the spectral bias of the network in SRDIP-FWI and quantify its role in multiscale velocity model building. Synthetic tests and field land data application demonstrate that SRDIP-FWI achieves superior resolution, improved accuracy and greater depth penetration compared to multiscale FWI. More importantly, SRDIP-FWI eliminates the need for manual frequency-band selection and time-window picking, substantially simplifying the inversion workflow. Overall, the proposed method provides a novel, adaptive and robust framework for accurate subsurface velocity model reconstruction.
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All authors Guangyuan Zou, Junlun Li, Feng Liu, Xuejing Zheng, Jianjian Xie, Guoyi Chen
Computational Physics · Cross-listed from cond-mat.mtrl-sci
A Transcorrelated Wave-Function Framework for Solids: An Application to Bulk and Defected Silicon
Kristoffer Simula, Johannes Hauskrecht, Evelin Martine Corvid Christlmaier et al. (+4 more)
Accurate wave-function descriptions of pristine and defected solids remain challenging due to the simultaneous presence of finite-size, basis-set, and correlation errors. While
embedding techniques alleviate finite-size effects and correlated wave-function approaches systematically improve correlation, basis-set incompleteness continues to limit practical accuracy. Here we present a study of transcorrelated (TC) many-body wave-function methods on properties of solid state systems. We augment the existing xTC theory to periodic systems, and establish an unified transcorrelated
embedding framework that integrates periodic TC theory with fragment-based correlated solvers. Using silicon as a test case, we validate the method against coupled-cluster, FCIQMC, and
diffusion Monte Carlo
benchmarks for bulk. Then we apply TC
embedding to calculation of formation energies of two silicon self-interstitials. The TC
Hamiltonian yields rapid basis convergence and quantitatively reliable defect formation energies at the triple-$\zeta$ level, substantially reducing the basis-set bottleneck for wave-function treatments of crystalline defects.
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All authors Kristoffer Simula, Johannes Hauskrecht, Evelin Martine Corvid Christlmaier, Pablo Lopez-Rios, Daniel Kats, Denis Usvyat, Ali Alavi
Plasma Physics
Ion-beam driven dust-cyclotron and dust-lower-hybrid instabilities in nonthermal dusty magnetoplasmas with dust-charge fluctuation
A. P. Misra, N. P. Acharya, S. Basnet et al. (+1 more)
We reveal a new dispersive
dust-lower-hybrid (DLH)-like mode that can couple to modified
dust-cyclotron (DC) waves in a dusty magnetoplasma by the influence of a streaming ion beam. Previous studies have overlooked such hybrid modes and the coupling in the study of resonant cyclotron instabilities in dusty magnetoplasmas. Using two-fluid models for positive ion beams and charged
dust grains, nonthermal $\kappa$-density distributions for electrons and positive ions, and orbital motion limited (OML) models for
dust-charge fluctuations, we derive a general linear dispersion relation for the coupled DLH and DC modes in the limit of when the hydrodynamic time scale is much longer than the
dust-charging time scale. The hybrid mode propagates with a frequency lower than the typical
dust-lower-hybrid frequency, $\widetilde{\omega}_{\rm{dl}}\equiv\omega_{\rm{pd}}\Omega_d/\sqrt{\omega^2_{\rm{pd}}+\Omega^2_d}$, where $\omega_{\rm{pd}}$ is the
dust-
plasma oscillation frequency and $\Omega_d$ is the
dust-cyclotron frequency. We obtain the growth rates of instabilities due to Cerenkov and cyclotron interactions and analyze them, taking into account the influences of the static
magnetic field, ion-to-electron temperature ratio, electron-to-
dust number density ratio,
dust-charge fluctuation, and superthermal electrons and ions. We find that the maximum growth rates tend to increase but reach steady states as the wave number increases. The instabilities reported here could be relevant to various
plasma environments, including space
plasmas (e.g., Earth's magnetosphere) and laboratory dusty
plasma experiments.
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All authors A. P. Misra, N. P. Acharya, S. Basnet, R. Khanal
Biological Physics
Frequency Locking to Environmental Forcing Suppresses Oscillatory Extinction in Phage-Bacteria Interactions
Hao-Neng Luo, Zhi-Xi Wu and Jian-Yue Guan
Bacteriophage-bacteria interactions are central to microbial ecology, influencing
evolution, biogeochemical cycles, and pathogen behavior. Most theoretical models assume static environments and passive bacterial hosts, neglecting the joint effects of bacterial traits and environmental fluctuations on coexistence dynamics. This limitation hinders the prediction of microbial persistence in dynamic ecosystems such as soils and oceans. Using a minimal ordinary differential equation framework, we demonstrate that environmental fluctuations can suppress destructive oscillations through resonance, promoting coexistence where static models otherwise predict collapse. Counterintuitively, we find that lower bacterial growth rates are helpful in enhancing survival under high infection pressure, elucidating the observed post-infection growth reduction. Our studies highlight bacterial hosts as active builders of ecological dynamics and environmental variation as a potential stabilizing force. Our findings thus bridge a theory-experiment gap and provide a framework for predicting microbial responses to environmental stress, which might have potential implications for phage therapy, microbiome management, and
climate-impacted community resilience as well.
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