Optics
GaN mid-IR plasmonics: low-loss epsilon-near-zero modes
Julia Inglés-Cerrillo, Maria Villanueva-Blanco, Benjamin Damilano et al. (+3 more)
Epsilon-near-zero (ENZ) materials, defined by $ | Re({\epsilon}) | < 1$, enable unique light propagation characteristics, including confinement within sub-wavelength regions. To reduce losses in this regime, materials with both near-zero permittivity and $n<1$ refractive index, known as near-zero-index (NZI) materials, are desired. When both conditions are satisfied, the resulting region is classified as a low-loss ENZ medium combining strong light confinement with reduced optical losses. To achieve this behavior in the mid-IR, heavily doped
semiconductors are required, and those compatible with current technologies are most desirable. This work provides the first in-depth study, supported by experimental demonstrations, of the plasmonic properties of highly doped GaN thin films on Si, exhibiting low optical losses and low-loss ENZ characteristics up to $3{\mu}m$. From the extracted optical parameters, the ENZ and NZI regions are determined and compared with the existing literature. As a result of the large polar character of nitrides, a hybridization of the surface plasmon and
phonon polaritons is observed, accompanied by a flat-dispersion of the high-energy mode (pinned near the
plasma frequency) indicative of its ENZ character. Establishing GaN as a viable platform for mid-IR ENZ-based plasmonics paves the way for integration into future infrared photonic technologies.
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All authors Julia Inglés-Cerrillo, Maria Villanueva-Blanco, Benjamin Damilano, Stéphane Vézian, Miguel Montes Bajo, Adrian Hierro
Atomic Physics · Cross-listed from quant-ph
High-harmonic generation from two weakly coupled molecules: a simple tight-binding model
Lina Bielke, Samuel Schöpa, Falk-Erik Wiechmann et al. (+2 more)
The generation of high harmonics is a strongly nonlinear effect that allows to probe properties of the target and to study electron dynamics in matter. It has been investigated in many different kinds of targets, including molecular gases,
liquids and solids. Recently, high-harmonic generation was studied in organic molecular
crystals by Wiechmann et al. [Nat. Commun. 16, 9890 (2025)]. It was found that the
laser-polarization-dependent harmonic yield is sensitive to the weak couplings between nearest- and next-nearest-neighbor molecules. In this paper, the impact of the
laser polarization angle and the intermolecular interaction on the harmonic yield is examined in detail using a simple but insightful two-dimensional tight-binding system that models a molecular dimer, i.e. two weakly coupled molecules. We find that the intensities of lower harmonic orders tend to maximize for a
laser polarization direction aligning with the molecular axes, whereas higher harmonic orders rather show the strongest yield for a polarization direction along the intermolecular axis. We further demonstrate that the harmonic order at which the maximum flips from the molecular to the intermolecular direction strongly depends on the intermolecular coupling strength. To gain a deeper insight into the origins of the findings, we include a detailed adiabatic analysis, showing that the flipping of the maximum yield towards the intermolecular direction is already contained qualitatively in the adiabatically following states.
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All authors Lina Bielke, Samuel Schöpa, Falk-Erik Wiechmann, Franziska Fennel, Dieter Bauer
Instrumentation and Detectors
New 1mm thick Silicon Drift Detectors for future researches of Kaonic Atoms and the Pauli Exclusion principle
F. Clozza, F. Sgaramella, L. Abbene et al. (+33 more)
Kaonic atoms, formed when a negatively charged kaon replaces an electron, provide a sensitive probe of the low-energy strong interaction via precision X-ray spectroscopy. The SIDDHARTA-2 experiment at the DA$\Phi$NE
collider employs high-performance Silicon Drift Detectors (SDDs) optimized for the 4-12 keV range to study light kaonic systems. In preparation for the EXKALIBUR phase, which targets heavier kaonic atoms, new 1 mm-thick SDDs have been developed with Politecnico di Milano and Fondazione Bruno Kessler. Their increased thickness enhances the
quantum efficiency by a factor of about two at 30 keV while preserving excellent energy resolution. These detectors are also intended for VIP-3, the next-generation test of the Pauli Exclusion Principle (PEP). Building on VIP-2, which set the most stringent limits on PEP-violating $K_{\alpha}$ transitions in copper, VIP-3 will extend the search to heavier elements such as Ag, Sn, and Zr. Preliminary measurements demonstrate efficient detection up to 30 keV, supporting future high-precision studies of the kaon-nucleon interaction and PEP in heavier systems.
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All authors F. Clozza, F. Sgaramella, L. Abbene, F. Artibani, M. Bazzi, G. Borghi, D. Bosnar, M. Bragadireanu, A. Buttacavoli, M. Carminati, A. Clozza, R. Del Grande, L. De Paolis, E. Demenev, C. Fiorini, I. Friščić, C. Guaraldo, M. Iliescu, M. Iwasaki, A. Khreptak, S. Manti, J. Marton, P. Moskal, H. Ohnishi, K. Piscicchia, F. Principato, A. Samusenko, A. Scordo, D. Sirghi, F. Sirghi, M. Skurzok, A. Spallone, K. Toho, J. Zmeskal, N. Zorzi, C. Curceanu
Applied Physics · Cross-listed from cond-mat.mtrl-sci
Accurate Modeling of Gate Leakage Currents in SiC Power MOSFETs
Ang Feng, Alexander Karl, Dominic Waldhör et al. (+3 more)
Silicon carbide (SiC) metal-
oxide-
semiconductor field-effect-transistors (MOSFETs) enable high-voltage and high-temperature power conversion. Compared to Si devices, they suffer from pronounced gate leakage due to the reduced electron tunneling barrier at the interface between SiC and amorphous silicon dioxide (a-SiO$_2$). We develop a self-consistent, physics-based simulation framework that couples electrostatics,
quantum tunneling, carrier transport, impact ionization, and charge trapping for both electrons and holes. The model quantitatively reproduces measured gate-current-voltage characteristics of SiC MOS capacitors over a wide temperature (80-573 K) range and a wide bias range without empirical fitting. Simulations reveal that conduction electrons in a-SiO$_2$ can trigger impact ionization, which generates electron-hole pairs, and leads to capture of holes in the
oxide bulk, thereby enhancing gate leakage current. The framework captures these coupled processes across multiple orders of magnitude in time and field, providing predictive capability for
oxide reliability. Although demonstrated for SiC devices, the methodology also applies to Si technologies that uses the same gate dielectric.
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All authors Ang Feng, Alexander Karl, Dominic Waldhör, Marina Avramenko, Peter Moens, Tibor Grasser
Instrumentation and Detectors
CZT Detectors for kaonic atoms spectroscopy
Francesco Artibani, Leonardo Abbene, Antonino Buttacavoli et al. (+36 more)
Cadmium zinc telluride (CZT) detectors offer excellent room-temperature energy resolution, making them well suited for X- and $\gamma$-ray spectroscopy in challenging environments. Within the SIDDHARTA-2 program at the DA$\Phi$NE
collider, a new CZT-based detection system has been developed to enable precision measurements of kaonic atom transitions in the intermediate mass range. In this work, we report the results of a calibration campaign performed with the
collider operating, aimed at assessing the detector performance. A dedicated setup, including an array of quasi-hemispherical CZT sensors and a $^{152}$Eu source, was used to characterize the spectral response. The reconstructed emission lines were fitted with a model accounting for Gaussian response and incomplete charge recollection tails, and the detector linearity was evaluated by comparing the measured peak positions with their nominal energies. The results demonstrate that the CZT detector exhibits excellent linearity and stable operation with the
collider on, confirming its suitability for future kaonic-atom spectroscopy at DA$\Phi$NE.
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All authors Francesco Artibani, Leonardo Abbene, Antonino Buttacavoli, Manuele Bettelli, Gaetano Gerardi, Fabio Principato, Andrea Zappettini, Massimiliano Bazzi, Giacomo Borghi, Damir Bosnar, Mario Bragadireanu, Marco Carminati, Alberto Clozza, Francesco Clozza, Raffaele Del Grande, Luca De Paolis, Carlo Fiorini, Ivica Friscic, Carlo Guaraldo, Mihail Iliescu, Masahiko Iwasaki, Aleksander Khreptak, Simone Manti, Johann Marton, Pawel Moskal, Fabrizio Napolitano, Hiroaki Ohnishi, Kristian Piscicchia, Francesco Sgaramella, Michal Silarski, Diana Laura Sirghi, Florin Sirghi, Magdalena Skurzok, Antonio Spallone, Kairo Toho, Oton Vazquez Doce, Johann Zmeskal, Catalina Curceanu, Alessandro Scordo
Classical Physics
Finite Element Prediction of Sintering Deformation in 3D-Printed Porcelain Filament
Fatima Hammoud and Charles Manière
Sintering of printed porcelain filaments can be strongly affected by overhang geometry, thin features, and printing-induced anisotropy. These effects are particularly difficult to simulate because they require accurately capturing the interplay between sintering kinetics, viscous deformation, and macroscopic anisotropy. In this study, a robust and predictive model is established experimentally using anisotropic sintering dilatometry combined with overhang-deformation calibration through finite element simulations (FEM). The sintering behavior is identified using a porosity-temperature-independent minimization strategy applied to multi-rate dilatometry. Pellet anisotropy is incorporated via FEM by imposing directional sintering stresses. The deformation behavior is then calibrated by adjusting the shear viscosity to match overhang shapes deformation. The resulting model is finally validated on overhanging bar geometries. This step-by-step approach provides a comprehensive assessment of porcelain sintering while accurately capturing deformation mechanisms.
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Classical Physics
Numerical analysis of the impact of water temperature setpoint and energy strategies on indoor pool performance
Younes Benakcha, Matthieu Labat, Ion Hazyuk et al. (+1 more)
Indoor swimming pools (ISPs) consume significant amounts of electrical and thermal energy to ensure the heating of water and air, ventilation, and maintaining adequate humidity levels. This is measured in GWh per year for large installations, such as Olympic swimming pools (SPs). In this paper, the problem is initially addressed using a phenomenological approach at steady state of the air-water coupling, based on a real case study. The aim is to identify the key phenomena and the constraints that are the most sensitive, including those related to water and air quality management. A key action lever is found in evaporation, and more specifically, water temperature and the indoor dewpoint temperature, which act as its precursors. In a second step, two different strategies were tested to reduce energy consumption for water heating. It was determined that a strategy which incorporates night setback in conjunction with a precise restart time yields a maximum gain of 4%. The second strategy aims to enhance the energy recovery of thermal
solar panels by enabling slight overheating of the pool. Its large volume provides effective energy storage, with estimated energy savings of up to 17% for a 1___ C overheating. This strategy appears to be a viable option, as it is straightforward to implement. However, the impact of water overheating on the energy consumption of AHU still needs to be analyzed and managed.
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All authors Younes Benakcha, Matthieu Labat, Ion Hazyuk, Stéphane Ginestet
Biological Physics · Cross-listed from cond-mat.soft
Size control guidelines for chemically active droplets
Guido Kusters and David Zwicker
Biological
cells and synthetic analogues use
liquid-
liquid phase separation to dynamically compartmentalize their environment for various applications. In many cases, multiple droplets need to coexist, and their size needs to be controlled, which is challenging because large droplets tend to grow at the expense of smaller ones. Chemical reactions can, in principle, control droplet sizes, but there are no clear guidelines on how to robustly achieve size control. To provide guidelines, we consider a binary fluid model driven out of
equilibrium by chemical reactions. We reveal two different classes of size-controlled droplets, depending on the ratio of droplet radius to the reaction-
diffusion length. Moreover, we determine parameter regimes in which droplets become small. Taken together, our theory allows us to separately predict the chemical reactions necessary for maintaining droplets of a given class or size.
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Fluid Dynamics
Regime Maps for Sloshing in Horizontal Cylindrical Tanks Under Vertical Acceleration
Francisco Monteiro, Tommaso De Maria, Samuel Ahizi et al. (+3 more)
Vertical sloshing in partially filled fuel tanks can significantly impact vehicle stability and structural integrity, particularly under harmonic accelerations near twice the sloshing natural frequency. In this regime, parametric resonance may arise, with nonlinear free-surface dynamics driving large-amplitude waves, interface break-up, and severe sloshing-induced mixing. In this work, we identify and characterize the distinct sloshing regimes associated with the lowest-frequency parametric instability, specifically when the external forcing frequency approaches twice the lowest natural frequency. Experiments were conducted in a transparent cylindrical tank with diameter D = 134.5 mm and length L = 336.3 mm. This work presents a data-driven approach for regime identification and classification that relies solely on high-speed
video recordings and circumvents the need for interface tracking. The method combines prototype-based data labeling with dimensionality reduction via multiscale proper orthogonal decomposition (mPOD) and automatic kernel-based classification. The results are summarized in a dimensionless regime map across three fill ratios, where stable waves, longitudinal and transverse mode shapes, and mode-competition regimes are distinguished. The developed map provides a predictive tool for assessing sloshing-induced loads, supporting structural and operational optimization of fuel systems.
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All authors Francisco Monteiro, Tommaso De Maria, Samuel Ahizi, Ramon Abarca, Giuseppe C.A. Caridi, Miguel A. Mendez
Optics
Electromagnetic polarization matrix and its physical interpretation
José J. Gil, Andreas Norrman, Ari T. Friberg et al. (+2 more)
Despite the intrinsic coupling between electric and
magnetic fields in random stationary light, their polarization properties are not mutually determined. A complete second-order description thus necessitates a joint electromagnetic treatment. The 6x6 electromagnetic polarization
matrix introduced here generalizes the conventional electric 3x3
matrix by incorporating both electric and
magnetic contributions together with their mutual correlations. It consists of diagonal 3x3 blocks, representing the electric and
magnetic polarization
matrices, and off-diagonal 3x3 blocks that encode the full structure of electric-
magnetic cross-correlations. The information contained in this
matrix can be interpreted through physically meaningful quantities such as active and reactive energy fluxes, in-phase and quadrature
alignment matrices, and global indices describing electric-
magnetic coupling. The formalism is applied to a field composed of two orthogonally propagating plane waves sharing a common linear electric polarization (a simple yet physically realizable configuration) that demonstrates the need for a general combined electric-
magnetic representation even in free space. This approach provides a comprehensive and unified framework for characterizing electromagnetic polarization beyond the electric-field description alone, bridging classical statistical optics with
quantum-like density-
matrix interpretations.
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All authors José J. Gil, Andreas Norrman, Ari T. Friberg, Behnaz Fazlpour, Tero Setälä
Atomic Physics · Cross-listed from quant-ph
Detection of photon-level signals embedded in sunlight with an atomic photodetector
Laura Zarraoa, Tomas Lamich, Sondos Elsehimy et al. (+2 more)
The detection of few-
photon signals in a broadband background is an extreme challenge for
photon counting, requiring filtering that accepts a narrow range of optical frequencies while strongly rejecting all others. Recent work [Zarraoa et. al, Phys. Rev. Res. 6, 033338 (2024)] demonstrated that trapped single atoms can act as low dark-count narrow-band photodetectors. Here we show that this “
quantum jump photodetector” (QJPD) approach can also detect
photon-level signals embedded in strong sunlight. Using a single rubidium atom as a QJPD, we count arrivals of individual narrow-band
laser photons embedded in sunlight powers of order $10^{10}$
photons/s. We derive a rate-equation model for the atom's internal-state dynamics in sunlight, and find quantitative agreement with experiment. Using this model, we calculate the channel capacity over a noisy communication channel when sending weak coherent states and detecting them in the presence of sunlight, achieving a representative rate of 0.5 bits per symbol when sending 150 probe
photons per 10 ms time-bin, embedded in 1 nW of sunlight (of order $10^{10}$
photons/s in the visible and near-infrared bands). The demonstration may benefit background-limited applications such as daytime light detection and ranging (
LIDAR), remote magnetometry, and free-space classical and
quantum optical communications.
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All authors Laura Zarraoa, Tomas Lamich, Sondos Elsehimy, Morgan W. Mitchell, Romain Veyron
Physics and Society · Cross-listed from cond-mat.stat-mech
Mean First Passage Time of the Symmetric Noisy Voter Model with Arbitrary Initial and Boundary Conditions
Rytis Kazakevičius and Aleksejus Kononovicius
Models of imitation and herding behavior often underestimate the role of individualistic actions and assume symmetric boundary conditions. However, real-world systems (e.g., electoral processes) frequently involve asymmetric boundaries. In this study, we explore how arbitrarily placed boundary conditions influence the mean first passage time in the symmetric noisy voter model, and how individualistic behavior amplifies this asymmetry. We derive exact analytical expressions for mean first passage time that accommodate any initial condition and two types of boundary configurations: (i) both boundaries absorbing, and (ii) one absorbing and one reflective. In both scenarios, mean first passage time exhibits a clear asymmetry with respect to the initial condition, shaped by the boundary placement and the rate of independent transitions.
Symmetry in mean first passage time emerges only when absorbing boundaries are equidistant from the midpoint. Additionally, we show that Kramers' law holds in both configurations when the rate of independent transitions is large. Our analytical results are in excellent agreement with numerical simulations, reinforcing the robustness of our findings.
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Optics · Cross-listed from cond-mat.str-el
Thouless pumps and universal geometry-induced drift velocity in multi-sliding quasi-periodic lattices
Zixun Xu and Yuan Yao
Quantized Thouless pumps in periodic systems, set by Chern numbers or Wannier-center winding, is by now fairly well established, whereas its quasi-periodic extensions still require further clarification. Here, we develop a general quantitative paradigm for bulk Thouless pumps in continuous models with spacetime quasi-periodicity, applicable to arbitrary spatial dimensions. Within this framework, the bulk pumping turns out to be governed by an emergent long wave-length effective potential. Based on this mechanism, we obtain our main result a universal relation between topological drifting and the geometry of quasi Brillouin zone. Reduced to periodic systems, our result gives an explicit and compact formula which enables us to directly calculate Chern numbers by microscopic data. These proposals are corroborated by simulations of one- and two-dimensional continuous moiré-type spacetime quasi-periodic
lattices, which exhibit stable, localized, directional drift in excellent agreement with the theory.
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Computational Physics · Cross-listed from quant-ph
Improved Ising Meson Spectroscopy Simulation on a Noisy Digital Quantum Device
Hao-Ti Hung, Isabel Nha Minh Le, Johannes Knolle et al. (+1 more)
The transverse-field Ising model serves as a paradigm for studying confinement and excitation spectra, particularly the emergence of $E_8$
symmetry near criticality. However, experimentally resolving the Ising
meson spectroscopy required to verify these
symmetries is challenging on near-term
quantum hardware due to the depth of
circuits required for real-time
evolution. Here, we demonstrate improved spectroscopy of confined excitations using two distinct error-resilient
circuit construction techniques on the IBM Torino device: first-order Trotter decomposition utilizing native fractional gates, and a tensor-network-based
circuit compression via Riemannian optimization. By analyzing the
Fourier spectrum of error-mitigated time-series data, we successfully identify key signatures of $E_8$
symmetry despite hardware noise. These results validate the viability of both
circuit compression and hardware-efficient compilation for probing complex topological phenomena on NISQ devices.
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All authors Hao-Ti Hung, Isabel Nha Minh Le, Johannes Knolle, Ying-Jer Kao
Applied Physics
Plasmonic nanopore to monitor in-pore chemistry
Weihong Wang, Shukun Weng, Ali Douaki et al. (+8 more)
In solid-state nanopores, achieving reliable control over pore aperture opening and closing (gating) remains a major challenge. Gating can be driven by the applied voltage involving electrically tunable chemical reactions, achieved by selecting appropriate compounds within the nanopore volume. In particular, cyclic precipitation and dissolution of metal phosphates can be triggered by regulating cation transport through an applied transmembrane voltage, thereby enabling reversible pore gating. Under negative bias, metal phosphate precipitates form inside the pore, obstructing ion flow and reducing current. Switching the polarity dissolves the precipitates, restoring ionic conductance. This process effectively produces a nanofluidic diode characterized by a remarkably high rectification ratio. To probe these localized chemical reactions more directly, we employed a plasmonic nanopore that generates strong confined fields, enabling surface-enhanced Raman scattering (SERS) measurements within the nanopore volume during cyclic gating. These measurements not only validate the proposed in-pore chemistry but also highlight the potential of plasmonic nanopores as powerful tools for monitoring nanoscale chemical processes with high spatial resolution.
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All authors Weihong Wang, Shukun Weng, Ali Douaki, German Lanzavecchia, Yanqiu Zou, Qifei Ma, Huaizhou Jin, Roman Krahne, Shangzhong Jin, Makusu Tsutsui, Denis Garoli
Data Analysis and Statistics · Cross-listed from cs.SI
Identifying preferred routes of sharing information on social networks
Rozhin Mohammadikian, Parsa Bigdeli, Behrouz Askari et al. (+1 more)
The spread of information has become faster and wider than ever with the advent of social network platforms. The question raised in this study is whether information dissemination in social networks is random or follows a discernible structure. Our results from real-world hashtag data suggest that the spread of hashtags is not random and follows specific patterns. This study proposes two preferential models to explore how news spreads on social media. Specifically, we examine global and local preferential selection models and demonstrate that information dissemination aligns with these patterns. According to these two models, information flows are distributed through specific paths on networks. This suggests that new information tends to propagate along the same paths as previous news, with the specific pathways varying depending on the type of content. Finally, an examination of the propagation of political hashtags on Twitter confirms the existence of these paths that also emerge from the two preferential models.
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All authors Rozhin Mohammadikian, Parsa Bigdeli, Behrouz Askari, G.Reza Jafari
Atomic Physics
Demonstration of magic dressing of $^3$He
Raymond Tat
A common concern in high-precision
neutron electric dipole moment (nEDM) experiments is that of
magnetic field stability. For static fields, this problem can be mitigated through the use of a superconducting holding field coil, which when operated in persistent current mode serves to stabilize the
magnetic field. However, such a solution is not viable when time-varying
magnetic fields are present, as is the case for the
spin dressing mode of the proposed nEDMSF (nEDM super-fluid) experiment. This experiment features an oscillating
magnetic field to dress the gyromagnetic ratios of $^3$He and
neutrons to the same value, a condition known as critical dressing. Fluctuations in the dressing field amplitude have the potential to disrupt this condition. Here, we investigate a modification to
spin dressing, termed “magic dressing,” which renders the system insensitive to small variations in dressing field amplitude. We further demonstrate the utility of this method for the single
spin-species case using a sample of polarized $^3$He. We find a dramatic increase in transverse relaxation time in the presence of
magnetic field gradients.
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Accelerator Physics
Study of fully coupled 3D envelope instability using automatic differentiation
Ji Qiang
Auto-differentiation is a powerful tool for computing derivatives of simulation results with respect to given parameters. In this letter, we have applied this tool to investigate the instability of a dynamics system that is governed by 21 ordinary differential equations. This second-order instability (named envelope instability) is driven by space-charge effects and has significant impact on the operational regimes of particle accelerators. Our study delves into the three-dimensional envelope instability, incorporating both transverse and longitudinal coupling. Conventionally, analyzing this complex system would necessitate solving 441 ordinary differential equations, which is computationally intractable. However, by employing auto-differentiation, we were able to track only 21 equations. This approach allowed us to uncover an additional instability stopband, which arises from space-charge-induced coupling and has not been reported in previous studies. This research highlights the significant advantages of auto-differentiation in analyzing complicated dynamical systems involving a large number of ordinary differential equations.
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Plasma Physics
Progress in relativistic laser-plasma interaction with kilotesla-level applied magnetic fields
K. Weichman, A. P. L. Robinson, M. Murakami et al. (+5 more)
We report on progress in the understanding of the effects of kilotesla-level applied
magnetic fields on relativistic
laser-
plasma interactions. Ongoing advances in
magnetic-field-generation techniques enable new and highly desirable phenomena, including
magnetic-field-amplification platforms with reversible sign, focusing ion acceleration, and bulk-relativistic
plasma heating. Building on recent advancements in
laser-
plasma interactions with applied
magnetic fields, we introduce simple models for evaluating the effects of applied
magnetic fields in
magnetic-field amplification, sheath-based ion acceleration, and direct
laser acceleration. These models indicate the feasibility of observing beneficial
magnetic-field effects under experimentally relevant conditions and offer a starting point for future experimental design.
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All authors K. Weichman, A. P. L. Robinson, M. Murakami, J. J. Santos, S. Fujioka, T. Toncian, J. P. Palastro, A. V. Arefiev
Plasma Physics
Laser-driven electrodynamic implosion of fast ions in a thin shell
S. Yu. Guskov, Ph. Korneev and M. Murakami
Collision of
laser-driven subrelativistic high density ion flows provides a way to create extremely compressed ion conglomerates and study their properties. This paper presents a theoretical study of the electrodynamic implosion of ions inside a hollow spherical or cylindrical shell irradiated by femtosecond petawatt
laser pulses. We propose to apply a very effective mechanism for ion acceleration in a selfconsistent field with strong charge separation, based on the oscillation of
laser accelerated fast electrons in this field near the thin shell. Fast electrons are generated on the outer side of the shell under irradiation by the intense
laser pulses. It is shown that ions, in particular
protons, may be accelerated at the implosion stage to energies of tens and hundreds of MeV when a sub-micrometer shell is irradiated by femtosecond
laser pulses with an intensity of 10^21 - 10^23 W cm^-2. .
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Plasma Physics
Integrated Sliding-Short/Probe Tuner with Doorknob Transition for High-Q Cavities
Saptarshi Biswas and Sven G. Bilén
We present an integrated three-knob tuner that internalizes impedance matching inside the launch adapter of a waveguide-fed, high-$Q$ cavity. The tuner combines a waveguide sliding short, a doorknob transition, and a micrometer-driven adjustable coaxial probe. A transmission-line/ABCD model is derived that maps the three mechanical degrees of freedom to the electrical objectives $\Gamma \rightarrow 0$, $\beta$, and $Q_{\rm L}$, explicitly including the fused-silica feedthrough capacitance. The model yields closed-form matching conditions and predicts the critical-coupling set. Full-wave FEM simulations and bench measurements validate the approach: with $h \approx 0.55$~mm and backshort distance $\approx 0.80$~mm, the return loss reaches $|S_{11}| \approx -30$~dB near 17.8–18.1~GHz while sustaining peak electric fields of $\sim 1.8 \times 10^5$~V/m at the nozzle (normalized to 1~W). The measured through loss of the launch assembly is $|S_{21}| \approx 0.7$–$0.8$~dB at resonance. A parametric study shows that backshort lengths $L_{\rm {bs}} \geq 0.5 \lambda_{\rm g}$ excite a parasitic stub resonance, introducing a second $S_{11}$ minimum and localizing energy behind the doorknob; keeping $L_{\rm {bs}} \leq 0.4 \lambda_g$ avoids this. In helium
plasma discharges at $P_{\rm {in}} = 10$~W, in-situ retuning of the short and probe maintained a favorable match as the
plasma impedance evolved, increasing absorbed power from $\sim 43\%$ to $\sim 76\%$ while increasing helium propellant flow rate from 25 to 351~sccm. The compact tuner eliminates external stub boxes and generalizes to other waveguide-coupled resonators and
plasma sources.
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Fluid Dynamics
Two-phase flow in porous metal foam flow fields of PEM fuel cells
Xingxiao Tao, Kai Sun, Rui Chen et al. (+4 more)
Porous metal foam (PMF) flow field is a potential option for
proton exchange membrane fuel
cells (PEMFCs) due to its excellent capabilities in gas distribution and water drainage. However, the gas-
liquid two-phase flow in the PMF flow field on the pore scale is still unclear. In this study, we investigate the gas-
liquid two-phase flow in the PMF flow field. Film, plug, and ligament flows are found in the hydrophilic PMF flow field, while slug and droplet flows are found in the hydrophobic PMF flow field. The results suggest that optimizing the pore size, increasing the metal foam surface hydrophobicity, and optimizing the operating condition are helpful for the water management of the PMF flow field. The frequency analysis of the pressure drop also shows that the dominant frequency can be used as an indicator to analyze the transition between different flow patterns.
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All authors Xingxiao Tao, Kai Sun, Rui Chen, Mengshan Suo, Huaiyu Liu, Zhizhao Che, Tianyou Wang
Fluid Dynamics
Mass transfer and water management in proton exchange membrane fuel cells with a composite foam-rib flow field
Wei Gao, Qifeng Li, Kai Sun et al. (+3 more)
Mass transfer capability of reactants and hydrothermal management is important for the performance and durability of
proton exchange membrane fuel
cells. In the conventional rib flow field, the oxygen transport is affected by the accumulation of under-rib
liquid water which causes excessive concentration loss and limits
cell performance. To improve the
cell performance, a composite foam-rib flow field structure is proposed by combining the metal foam flow field and the conventional rib flow field. The proposed design is simulated by using a three-dimensional homogeneous non-isothermal numerical model. The results show that the composite foam-rib flow field, by improving the oxygen transfer and water removal capabilities under the ribs, can improve the oxygen concentration and current density without increasing the pumping power, thus improving the
cell performance under different conditions. The key parameters of the composite foam-rib flow field are optimized. With the optimal metal foam filling ratio of 0.75 and porosity of 0.85, the peak power density and the limiting current density for the composite foam-rib flow field are higher than the conventional rib flow field by 5.20% and 22.68%.
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All authors Wei Gao, Qifeng Li, Kai Sun, Rui Chen, Zhizhao Che, Tianyou Wang
Chemical Physics
Efficient Quantum Simulation of Non-Adiabatic Molecular Dynamics with Precise Electronic Structure
Tianyi Li, Yumeng Zeng, Qiming Ding et al. (+6 more)
In the study of non-adiabatic chemical processes such as photocatalysis and photosynthesis, non-adiabatic molecular dynamics (NAMD) is an indispensable theoretical tool, which requires precise potential energy surfaces (PESs) of ground and excited states.
Quantum computing offers promising potential for calculating PESs that are intractable for classical computers. However, its realistic application poses significant challenges to the development of
quantum algorithms that are sufficiently general to enable efficient and precise PES calculations across chemical systems with diverse properties, as well as to seamlessly adapt existing NAMD theories to
quantum computing. In this work, we introduce a
quantum-adapted extension to the Landau-Zener-Surface-Hopping (LZSH) NAMD. This extension incorporates
curvature-driven hopping corrections that protect the population
evolution while maintaining the efficiency gained from avoiding the computation of non-adiabatic couplings (NACs), as well as preserving the trajectory independence that enables parallelization. Furthermore, to ensure the high-precision PESs required for surface hopping dynamics, we develop a sub-microhartree-accurate PES calculation protocol. This protocol supports active space selection, enables parallel acceleration either on
quantum or classical clusters, and demonstrates adaptability to diverse chemical systems - including the charged H3+ ion and the C2H4 molecule, a prototypical multi-reference
benchmark. This work paves the way for practical application of
quantum computing in NAMD, showcasing the potential of parallel simulation on
quantum-classical heterogeneous clusters for ab-initio computational chemistry.
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All authors Tianyi Li, Yumeng Zeng, Qiming Ding, Zixuan Huo, Xiaosi Xu, Jiajun Ren, Diandong Tang, Xiaoxia Cai, Xiao Yuan
Fluid Dynamics
Singular jets during droplet impact on superhydrophobic surfaces
Xiaoyun Peng, Tianyou Wang, Feifei Jia et al. (+3 more)
Hypothesis: The impact of droplets is prevalent in numerous applications, and jetting during droplet impact is a critical process controlling the dispersal and transport of
liquid. New jetting dynamics are expected in different conditions of droplet impact on super-hydrophobic surfaces, such as new jetting phenomena, mechanisms, and regimes. Experiments: In this experimental study of droplet impact on super-hydrophobic surfaces, the Weber number and the Ohnesorge number are varied in a wide range, and the impact process is analyzed theoretically. Findings: We identify a new type of singular jets, i.e., singular jets induced by horizontal inertia (HI singular jets), besides the previously studied singular jets induced by capillary deformation (CD singular jets). For CD singular jets, the formation of the cavity is due to the propagation of capillary waves on the droplet surface; while for HI singular jets, the cavity formation is due to the large horizontal inertia of the toroidal edge during the retraction of the droplet after the maximum spreading. Key steps of the impact process are analyzed quantitatively, including the spreading of the droplet, the formation and the collapse of the spire, the formation and retraction of the cavity, and finally the formation of singular jets. A regime map for the formation of singular jets is obtained, and scaling relationships for the transition conditions between different regimes are analyzed.
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All authors Xiaoyun Peng, Tianyou Wang, Feifei Jia, Kai Sun, Zhe Li, Zhizhao Che
Fluid Dynamics
Instability triggered by mixed convection in a thin fluid layer
Florian Rein, Keaton J. Burns, Stefan G. Llewellyn Smith et al. (+3 more)
We investigate the convective stability of a thin, infinite fluid layer with a rectangular cross-section, subject to imposed heat fluxes at the top and bottom and fixed temperature along the vertical sides. The instability threshold depends on the Prandtl number as well as the normalized flux difference ($f$) and decreases with the aspect ratio ($\epsilon$), following a $\epsilon f^{-1}$ power law. Using 3D initial value and 2D
eigenvalue calculations, we identify a dominant 3D mode characterized by two transverse standing waves attached to the domain edges. We characterize the dominant mode's frequency and transverse wave number as functions of the Rayleigh number and aspect ratio. An analytical asymptotic solution for the base state in the bulk is obtained, valid over most of the domain and increasingly accurate for lower aspect ratios. A local stability analysis, based on the analytical base state, reveals oscillatory transverse instabilities consistent with the global instability characteristics. The source term for this most unstable mode appears to be interactions between vertical shear and horizontal temperature gradients.
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All authors Florian Rein, Keaton J. Burns, Stefan G. Llewellyn Smith, William R. Young, Benjamin Favier, Michael Le Bars
Instrumentation and Detectors · Cross-listed from hep-ex
Rare Event Searches Using Cryogenic Detectors via Direct Detection Methods
S. Das, R. Dey, V.K.S. Kashyap et al. (+5 more)
Cryogenic detectors are at the forefront of rare-event search experiments, including direct detection of dark matter, coherent elastic
neutrino-
nucleus scattering, neutrinoless double-beta decay, and searches for fractionally charged particles. Their unique ability to achieve ultra-low energy thresholds, typically O(eV-100 eV), together with excellent energy resolution and effective background suppression, makes them sensitive to extremely faint signals from rare interactions. These rare particle interactions produce
phonons, ionization, or scintillation, depending on the target medium, which are registered by specialized sensors and converted into measurable signals. This review summarizes the underlying detection principles, surveys major experiments and recent results, examines forthcoming initiatives, and outlines the evolving role of cryogenic detectors in advancing the frontiers of rare-event physics.
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All authors S. Das, R. Dey, V.K.S. Kashyap, B. Mohanty, D. Mondal, S. Banik, M. Chaudhuri, V. Iyer
Applied Physics
Geant4 Modeling of Energy and Charge Deposition in Satellites Solar Cells
Youssef Abouhussien and Gennady Miloshevsky
Understanding radiation effects in spacecraft components is critical for predicting long-term performance degradation. In this work, a Geant4 Monte Carlo model is developed to compute charge and energy deposition in satellite
solar-
cell materials exposed to electrons,
protons, and X-ray environments. The model is validated against published experimental and computational
benchmarks and shows strong agreement across multiple energy ranges. Power-density deposition profiles are then evaluated for a multi-layer
solar-
cell structure under blackbody soft X-rays, mono-energetic X-rays, and high-energy electrons. The results show that low-energy X-rays dominate damage in surface layers, while high-energy particles penetrate deeper into
semiconductor and substrate layers, posing risk to electronic components. These findings highlight the importance of radiation-specific shielding strategies for space
solar-
cell design.
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Plasma Physics · Cross-listed from astro-ph.SR
Solitary Alfvén Waves
Zesen Huang, Marco Velli, Chen Shi et al. (+1 more)
We present the solitary Alfvén wave as an ideal nonlinear Alfvénic solution in the solitary far-field limit and construct a three-dimensional numerical model – an Alfvénon. The model is characterized by an unperturbed far field, quasi-constant $|\boldsymbol{B}|$, and open field-line
topology. Direct MHD simulations of the Alfvénon show coherent finite-time propagation, confirming that it behaves as a nonlinear solitary Alfvénic solution under ideal MHD
evolution.
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All authors Zesen Huang, Marco Velli, Chen Shi, Yuliang Ding