Atomic Physics · Cross-listed from cond-mat.dis-nn
Quenched fluctuation-induced force arising from polarization disorder
Bing-Sui Lu
We investigate the zero-temperature behavior of the fluctuation force induced by the quenched disorder of electric dipoles frozen randomly into a material. Examples of such materials include relaxor ferroelectrics. In terms of the setup and geometry, we focus on a layered system comprising two coplanar semi-infinite slabs separated by a distance $\ell$ as well as a system comprising a neutral atom in the
vacuum located at a distance $\ell$ above the surface of a semi-infinite slab. For both systems, we consider the cases where the quenched random dipolar disorder occurs inside the bulk as well as on the surface of the slabs. In all of these cases, we find that the bulk (surface) dipolar disorder-induced force grows with the mean square quenched electric dipole moment per unit volume (area). The bulk (surface) dipolar disorder-induced pressure between two semi-infinite single-layered slabs decays with $\ell^{-3}$ ($\ell^{-4}$), whereas the bulk (surface) dipolar disorder-induced force on an atom in the
vacuum near a slab containing the disorder decays with $\ell^{-4}$ ($\ell^{-5}$). We also find that the quenched dipolar disorder-induced force between two coplanar slabs can be repulsive in a three-layered dielectric system that obeys a zero-frequency analogue of the Dzyaloshinskii-Lifshitz-Pitaevskii condition, and serve to enhance the “nanolevitation effect" if the latter is present in the disorder-free system.
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Optics
Demonstration of a High-Q Subwavelength Dielectric Nanocylinder
Dayang Li, Simon Klinck Borregaard, Jesper Mørk et al. (+2 more)
The development of subwavelength dielectric cavities is essential for reducing the size of photonic devices and enabling dense optoelectronic integration. However, previouslysubwavelengthoptical cavities exhibit demonstrated Q-factors <400, limiting their applications. Here, we demonstrate a high-Q subwavelength nanocylinder by leveraging bound states in the continuum (BIC). We track BIC modes of different longitudinal orders while maintaining an ultrasmall footprint. We find that the Q-factor initially increases but then saturates at higher orders. By linking quasi-normal-mode perturbation theory with coupled-mode analysis, we reveal the physical origin of this saturation and identify an optimized dimension that balances performance with fabrication feasibility. By suspending this design in free space using nanobridges and optimizing the nanofabrication process, we experimentally realize an InP subwavelength nanocylinder with a measured Q-factor exceeding 1000. Compared with a lower-Q substrate-supported counterpart, the suspended high-Q BIC nanocylinder exhibits stronger scattering and photoluminescence signals. Our work provides a route to high-Q optical devices with ultrasmall footprints.
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All authors Dayang Li, Simon Klinck Borregaard, Jesper Mørk, Meng Xiong, Yi Yu
Applied Physics · Cross-listed from eess.SP
A Dual-Mode FM/AM Modulator Based on a Time-Varying Inverting Integrator
Azalía G. Gil, Alfonso T. Muriel-Barrado, Mario Pérez-Escribano et al. (+2 more)
This paper presents the analysis, design, fabrication, and experimental validation of a dual-mode frequency/amplitude modulator based on a time-modulated varactor diode. By exploiting the varactor as a time-varying capacitor in combination with an operational amplifier configured as an inverting integrator and a passband filter, the proposed
circuit generates frequency-modulated (FM) signals in an efficient manner. Amplitude-modulated (AM) signals can also be obtained with a simple modification. The implementation, realized in microstrip technology, leverages the unique properties of time-modulated electronic components, particularly their inherent frequency-mixing capability. Analytical expressions are derived to predict the characteristics of the generated waveforms, and their accuracy is verified through numerical simulations performed in Keysight ADS. A microstrip PCB prototype is then fabricated and experimentally characterized. The measured results show excellent agreement with both the theoretical predictions and the numerical simulations. The proposed approach demonstrates the potential of time-varying capacitors as an attractive alternative to conventional FM techniques for telecommunications and radar applications.
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All authors Azalía G. Gil, Alfonso T. Muriel-Barrado, Mario Pérez-Escribano, Carlos Molero, Antonio Alex-Amor
Instrumentation and Detectors
The CROSS experiment: detector construction, background projection, and sensitivity to $^{100}$Mo $0\nu2\beta$ decay
D. Auguste, A.S. Barabash, G. Benato et al. (+42 more)
The CROSS experiment to search for neutrinoless double-beta ($0\nu2\beta$) decay in $^{100}$Mo with the help of an array of scintillating cryogenic calorimeters, containing 4.9 kg of $^{100}$Mo, has been ongoing in a low-background setup at the Canfranc underground laboratory (Spain) since mid-November 2025. In this paper, we present the construction of the CROSS detector and the description of Geant4-based Monte Carlo simulations of expected background in the region of interest. The simulations predict the background index in a 100-keV-wide interval centered at the $Q$-value of $^{100}$Mo (3034 keV) on the level of 3.2(5) $\times$ 10$^{-3}$ cnts/keV/kg/yr. Taking into account an 18% deadtime induced by the
muon veto cut and a typical 90% duty cycle of the facility, such background level would allow to reach the world-leading sensitivity to $^{100}$Mo $0\nu2\beta$ decay (lim $T_{1/2} \sim 4 \times 10^{24}$ yr) in 1 year of data taking. Considering conservatively a factor 3 (10) worse background index due to unpredictable radioactive contamination of construction materials and/or detector performance, a 2-yr-long operation of the CROSS array would be still compatible with the best (competitive) sensitivity to $0\nu2\beta$ decay in $^{100}$Mo.
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All authors D. Auguste, A.S. Barabash, G. Benato, V. Berest, L. Bergé, M. Buchynska, J.M. Calvo-Mozota, J. Cao, P. Carniti, M. Chapellier, D. Cintas, I. Cojocari, I. Dafinei, F.A. Danevich, M. De Deo, A. Drobizhev, L. Dumoulin, F. Ferri, A. Giuliani, C. Gotti, Ph. Gras, A. Ianni, V.V. Kobychev, Yu. G. Kolomensky, S.I. Konovalov, P. Loaiza, P. de Marcillac, S. Marnieros, C.A. Marrache-Kikuchi, M. Martinez, C. Nones, E. Olivieri, A. Ortiz de Solórzano, M. Pageot, Y. Peinaud, G. Pessina, D.V. Poda, Ph. Rosier, B. Schmidt, R. Serino, V.I. Tretyak, V.I. Umatov, M. Velazquez, M. Zarytskyy, A. Zolotarova
Chemical Physics
Preparing Small Gaussian Basis for Highly Accurate Ab Initio Description of Lithium Rydberg States
Jan Šmydke, Benjamín Andreides and Simona Dubcová
A new small and highly accurate Gaussian basis set has been developed for the ab initio description of $^2$Li Rydberg excited states up to $n = 7$ and S, P, D, F, and G angular momentum
symmetry, and the appropriate optimization protocol is presented. The obtained Rydberg excitation energies are compared with results from other highly accurate approaches. At the EOM-CCSD level of theory the new basis exhibits higher than $10^{-2}$ eV accuracy of the excitation energies and the ionization potential and provides superior results than an analogous universal Gaussian basis set, while utilizing even smaller number of basis functions. Plots of the 1-dimensional Rydberg-orbital cuts reveal a regular nodal structure along the logarithmic scale of the atomic radius reaching tens of angstrom far from the
nucleus. The presented Rydberg basis set generation methodology is an important step towards routine ab initio Rydberg-state related investigations of more complex systems, such as large atoms and polyatomic molecules.
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Optics
Platicon purification in self-injection locking regime via gain switching
Chengcong Li, Tatiana S. Tebeneva, Valery E. Lobanov et al. (+4 more)
Integrated photonic devices leveraging optical frequency microcombs have emerged as essential instruments for modern photonic systems, prized for their chip-scale footprint, high energy efficiency, and inherent stability. This work introduces a novel approach to microwave photonic oscillator based on generation of a Kerr platicon microcomb by a gain-switched self-injection-locked distributed feedback (DFB)
laser diode. The system leverages direct modulation of the current of the
laser diode, generating optical sidebands around the pump line. The beatnote between the Kerr comb lines and sidebands of the modulated pump at a high-speed photodetector allows to obtain tunable, low-noise microwave signals at frequencies close to the platicon repetition rate, which is many times higher than used for gain switching. We experimentally demonstrate continuous microwave signal frequency tuning from 100 MHz to 3.6 GHz by sweeping the modulation frequency, thereby shifting the generated sidebands relative to a platicon beatnote. We match third harmonics of the modulation frequency of the gain-switch signal with the free spectral range of the microresonator simultaneously generating the platicon microcomb. That leads to significant spectral purification of the platicon beatnote decreasing its phase noise by more than 30 dB. The novel architecture proposed offers a robust and versatile method for microwave synthesis, presenting significant potential for the advancement of integrated microwave photonic systems and their applications in communications, sensing, and metrology.
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All authors Chengcong Li, Tatiana S. Tebeneva, Valery E. Lobanov, Junqiu Liu, Dmitry A. Chermoshentsev, Igor A. Bilenko, Artem E. Shitikov
Medical Physics
Amplitude-based echo-mode speed-of-sound tomography
Michael Jaeger and Marina Eckermann
The tissue's speed of sound (SoS) is a promising marker for non-invasive and zero-dose diagnosis of diseases such as cancer or liver steatosis. Computed ultrasound
tomography in echo mode (CUTE) retrieves spatially resolved SoS using pulse-echo ultrasound, by analysing the variation of echoes when probed with varying pairs of transmit- and receive-steering angles. This analysis conventionally focuses on the echo phase shift, which is interpreted as differential time-of-flight (dToF) and related to SoS. While promising results have been obtained, the trade-off between beamwidth and angular aperture not only limits spatial resolution but also leads to artefactual noise in media with short-scale SoS variations. To overcome this limitation, we propose an alternative approach: for each echo, instead of reducing the angle-dependent variations to a single parameter (the dToF), we retrieve aberration profiles with sub-beamwidth resolution by inverting a model that relates these profiles to the echo amplitudes detected for all angle pairs. We demonstrate in simulations that this amplitude-based (a-CUTE) approach results in substantially improved spatial resolution and reduced artifacts compared to dToF-CUTE. Physical phantom and preliminary in vivo results confirm the feasibility of this novel method in physical data.
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Space Physics · Cross-listed from astro-ph.SR
The Internal Magnetic Field Structure of ICMEs in the Heliosphere
Ziwei Huang, Zhenjun Zhou, Yudong Ye et al. (+7 more)
Interplanetary coronal mass ejections (ICMEs) are major drivers of heliospheric disturbances and space-weather effects. Here we present a multi-spacecraft study of 96
magnetic clouds (MCs) distributed over a broad range of heliocentric distances, and reconstruct their internal
magnetic structure with a uniform-twist Gold–Hoyle (GH) flux-rope model. From the fits, we derive the axial field strength $B_0$, the twist density (turn density) $\tau$, the GH parameter $\omega$, and the integrated twist number $n$. We find that $B_0$ and the turn density $\tau$ both decrease with increasing heliocentric distance, consistent with expansion and axial stretching during propagation. A key result is that the upper envelope in the $\tau$–$R$ plane corresponds to a nearly constant boundary in the dimensionless GH parameter $\omega=2\pi R\tau$, close to $\omega\sim2$. Therefore, the inferred upper value of $\tau$ is not scale-independent, but follows $\tau_{\max}\simeq \omega_{\max}/(2\pi R)$ for a given flux-rope radius. In contrast, the estimated integrated turn number $n$ shows no similarly clear radial organization in the present sample. This study investigates the ICME structure and
magnetic field characteristics across heliocentric distances from 0.07 to 5.4~AU, thereby providing observational constraints on the large-scale
evolution of interplanetary
magnetic flux ropes.
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All authors Ziwei Huang, Zhenjun Zhou, Yudong Ye, Ming Xiong, Yuming Wang, Yutian Chi, Daniel Heyner, Hans-Ulrich Auster, Ingo Richter, Beatriz Sanchez-Cano
Accelerator Physics
Reinforcement Learning applied to Optimization of LHC beams in the CERN Proton Synchrotron
Joel Axel Wulff and Alexandre Lasheen
The longitudinal triple splitting in the CERN
Proton Synchrotron (PS) is a key rf manipulation defining the 25 ns bunch spacing delivered to the Large
Hadron Collider (LHC). We present an automated optimization of this manipulation based on machine learning. Successive manipulations with rf systems at multiple harmonics of the revolution frequency are performed in the PS. Each bunch injected from the PS Booster (PSB) is split into twelve bunches with ideally identical longitudinal beam parameters. Precise rf voltage and phase settings are required to minimize bunch-by-bunch variations in intensity, longitudinal emittance, and bunch shape. Our setup combines two distinct parts: a convolutional neural network providing an initial phase correction from the
evolution of longitudinal bunch profiles during the splitting process, and two sequential Soft-Actor-Critic (SAC) reinforcement-learning
agents that refine cavity phases and voltages. The models are trained on data from Beam Longitudinal Dynamics (BLonD) tracking simulations augmented by simulated uncertainties, including noise evaluated from measurements, to enable training and robust transfer to the machine. First tests in 2022 reached target splitting quality in fewer than ten optimization steps on average, matching or outperforming manual adjustments. This led to operational deployment of an on-demand version, followed by a fully autonomous controller in March 2025. This controller has been available to operations since, representing one of the first reinforcement-learning-based systems for beam quality optimization deployed in the CERN injector complex.
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Fluid Dynamics
Extracting informative vortical structures of turbulent wake-extreme vortex gust interactions with machine learning
Ryo Koshikawa and Kai Fukami
This study considers extracting causally important vortical structures from the extreme
vortex gust-airfoil interaction at a chord-based Reynolds number of $5000$. This extraction is achieved by decomposing a given vortical flow snapshot into its informative and residual components based on the contribution to an arbitrary future target variable with convolutional information-theoretic learning. For the current
vortex-airfoil interactions that exhibit transient and multiscale flow characteristics, we first examine the important vortical structures with respect to a future lift coefficient. While the
vortex cores are primarily highlighted before
vortex impingement, the emerging shear layers are additionally captured after the massive separation, which is evident from a comparison to an instantaneous force-element analysis. We further take the scale-dependent energy transfer as a future variable of interest to examine its impact on the extracted informative structures compared to the lift-associated structures. They are distinct from the lift-based structures in the early stage of the gust encounter yet become similar after impingement, revealing an analogy between informative structures across different transient aerodynamic mechanisms. The present data-driven approach selectively extracts the specific important flow structures responsible for the physics of interest, which can support studying a range of transient aerodynamic flows from the causal, data-driven perspective.
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Optics
Resolving multiple layer thicknesses and birefringence in thin films with an optical in-line Roll-to-Roll characterization setup
Søren A. R. Kynde, Astrid T. Rømer, Abdelouadoud Mammeri et al. (+4 more)
Optical techniques provide a fast and flexible path to material inspection. In particular, the investigation of key metrics during material production can help obtain the optimal parameters to achieve desired material functionality as well as to ensure product quality. Here we present an optical imaging setup designed for fast material inspection in a roll-to-roll deposition environment. The method allows for robust simultaneous determination of thickness in the range from 0.3 to 110 micrometers of multiple layers of transparent or semi-transparent materials in the form of a free film or a film deposited on a thicker transparent substrate. The PEDOT and ZnO materials chosen for this proof of concept are relevant for the fabrication of organic
solar cells. Additionally, the method may be used to characterize birefringence.
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All authors Søren A. R. Kynde, Astrid T. Rømer, Abdelouadoud Mammeri, Jens W. Andreasen, Moises Espindola, Matteo Ciambezi, Søren A. Jensen
Physics and Society
Structure of System-Specific Hazard Modeling for Physical Infrastructures in a Climate Change Context
Matthieu Dutel
This paper addresses the definition and modeling of hazards in the context of physical systems, particularly infrastructures, that are affected by
climate change. The paper highlights that hazards are system-dependent, meaning what constitutes a hazard for one system (e.g., humans) may not be the same for another (e.g., infrastructures). The paper also highlights that extreme intensity distribution may evolve in a region without necessarily constituting a hazard for a specific system. These distinctions are crucial for risk assessment and adaptation strategies in a changing
climate. The paper implements a simple threshold-based hazard model -Boolean Hazard Model with Probability -to focus exclusively on system-specific hazard definition in climatechange context. Use cases illustrate how this approach adapts to different systems and hazard types. The model produces time-evolving hazard maps, delivering hazard data tailored to both hazard type and infrastructure characteristics. The model provides hazard data tailored to specific hazard types and physical systems, with a focus on infrastructure. The use cases demonstrate their practical value and potential for broader application in multi-infrastructure and multi-hazard exposure modeling.
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Optics
Signature of Magnon-Raman Phonon-Polariton Condensation in a Cavity via Transverse Pumping
Subrata Chakraborty and Shishir Kumar Pandey
Polaritons—hybrid light-matter quasiparticles—provide a versatile platform for dynamically controlling a wide range of condensed matter systems. While conventional polaritonic platforms rely on direct dipole coupling, controlling dipole-forbidden or Raman-active
lattice and
spin excitations remains challenging due to optical selection rules and the limitations of THz cavities. Here, we propose a theoretical platform for realizing a continuous-wave
magnon–Raman
phonon–polariton condensate. By
embedding a
magnetic medium hosting strongly coupled
magnon and Raman-active
phonon (MRP) modes inside an optical microcavity under continuous-wave transverse
laser pumping, we derive the stationary-state phase diagram and demonstrate the emerging signature of distinct MRP condensation phases under critical conditions. Furthermore, since the bare
magnon frequency is tunable via an external
magnetic field, we show that the transverse pump frequency and the external
magnetic field-dependent
magnon simultaneously as highly flexible control parameters for exploring and controlling macroscopic
quantum phenomena at the interface of cavity
quantum optics,
lattice dynamics, and
quantum magnetism.
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Computational Physics · Cross-listed from cond-mat.mtrl-sci
Percolating Multifractal Domains at a Polymorphic Phase Boundary
Yuan-Jinsheng Liu, Xu Tian, Jiahui Zhai et al. (+1 more)
Giant piezoelectricity in ferroelectrics is commonly associated with phase-boundary instabilities, among which the polymorphic phase boundary (PPB) is a prominent example conventionally attributed to the coexistence of ferroelectric phases. Here, using large-scale molecular dynamics simulations of the lead-free (K,Na)NbO3-(Bi,Na)ZrO3 solid solutions, we show that the PPB hosts a percolating multifractal polar domain which governs the dielectric and piezoelectric responses. By quantifying the global fractal dimension and multifractal spectrum width of this polar network, we identify fractal connectivity and multiscale heterogeneity as microstructural order parameters for the PPB. The maximum reversible piezoelectric response occurs when the fractal-domain volume fraction approaches the three-dimensional percolation threshold, suggesting that near-critical polar connectivity enables
giant reversible electromechanical coupling. In this mechanism, the fractal backbone preserves polar
memory and provides the restoring force required for reversibility, while the surrounding nonfractal regions supply the polar compliance needed for large polarization rotation and strain. These results establish percolating multifractal polar domains as a microscopic mechanism for PPB-enhanced piezoelectricity and suggest fractal connectivity as a design parameter for high-performance piezoelectrics.
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All authors Yuan-Jinsheng Liu, Xu Tian, Jiahui Zhai, Shi Liu
Chemical Physics · Cross-listed from cond-mat.soft
Mode-Resolved Light Scattering Recovers Polymer Thermodynamics in Solutions with Trace Large-Mass Scatterers
Noriaki Mizumoto, Takashi Yasuda, Hiroshi Hinou et al. (+1 more)
Light scattering provides direct access to
polymer conformations and thermodynamics. However, trace large-mass scatterers such as aggregates and nanobubbles form unavoidably in
polymer solutions and dominate the scattered intensity, obscuring the intrinsic
polymer signal. We demonstrate that resolving the static scattering intensity by molecular mobility cleanly separates the
polymer and large-scatterer contributions. Applying this mode-resolved analysis to aqueous poly(ethylene glycol) solutions, we isolate the
polymer scattering even when these scatterers account for more than 90 % of the total intensity. The resolved
polymer intensity recovers the universal osmotic equation of state from the dilute to the semidilute regime over 288 to 358 K. This approach establishes a reliable basis for measuring the thermodynamics of interacting macromolecules in solutions where irreproducible large-mass scatterers have precluded quantitative analysis.
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All authors Noriaki Mizumoto, Takashi Yasuda, Hiroshi Hinou, Xiang Li
Accelerator Physics
Cherenkov Diffraction Radiation Interferometry for Beam Divergence Diagnostics
Artem Novokshonov
Cherenkov radiation (ChR) is widely used in charged-beam diagnostics, including bunch-length measurements and beam-loss monitoring. Synchrotron radiation (SR) interferometry is a well-established technique for measuring beam size. This work combines these approaches by proposing a ChR-based interferometric method for measuring beam divergence.
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Plasma Physics
One dimensional high-order moment models with realistic collisions for nonequilibrium ion transport in weakly ionized plasmas
Anatole Berger and Alejandro Alvarez Laguna
Ion-neutral collisions are fundamental in the transport of partially ionized
plasmas. When collisional scales are comparable to the system scales or the electric field is strong, nonequilibrium conditions for the ions arise that are beyond classical transport models due to large drifts, strong heat flux, and temperature anisotropy. In this paper, we propose the resolution of non-linear high-order moment closures for simulating nonequilibrium ion dynamics in one-dimensional weakly ionized
plasmas. We compare a four-moment anisotropic Maxwellian model (mass, axial momentum, and axial and perpendicular energies), a five-moment
hyperbolic quadrature-based model (first five axial moments), and a novel six-moment
hyperbolic quadrature-based model (first five axial moments + perpendicular energy). We derive analytical collision source terms from the Boltzmann operator for ion-neutral scattering with arbitrary differential cross sections. This formulation generalizes the Chapman-Cowling theory for arbitrary drift velocities, temperature anisotropies, and heat flux, ensuring strictly realizable distributions. The models are validated via non-linear simulations benchmarked against kinetic solutions for argon
plasmas with realistic cross sections (0.05-500 mTorr). We test a bounded
plasma between floating walls and a direct-current discharge. The six-moment model robustly captures ion dynamics, particularly under strong nonequilibrium, where anisotropy and heat flux are non-local. It reconstructs the distribution function with high fidelity, without noise, and at a cost comparable to fluid models in a self-consistent manner.
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Optics
Generation of high-fluence and high-intensity hard x-ray attosecond pulses at European XFEL
Ichiro Inoue, Ulrike Boesenberg, Rustam Rysov et al. (+41 more)
By combining hard x-ray attosecond pulses from the European XFEL with total-reflection focusing x-ray optics, we generated nanofocused hard x-ray attosecond pulses with intensities and fluences comparable to the highest values attained in the hard x-ray regime. A peak intensity on the order of 10$^{20}$ W/cm$^2$ is confirmed through the observation of saturation in amplified spontaneous emission from copper atoms. These x-ray pulses enable new scientific opportunities, including the exploration of higher-order nonlinear light–matter interactions, damage-free structure determination, and coherent control of atoms and molecules.
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All authors Ichiro Inoue, Ulrike Boesenberg, Rustam Rysov, Takahiro Sato, Ichika Harima, Chenzhi Xu, Jia Liu, Thomas M. Linker, Zain Abhari, Andrei Benediktovitch, Uwe Bergmann, Ye Chen, Lu Cao, Winfried Decking, Gianluca Geloni, Marc Guetg, Trey Guest, Aliaksei Halavanau, Jörg Hallmann, Takashi Kimura, Naresh Kujala, Aliaksandr Leonau, Shan Liu, Tianyun Long, Johannes Möller, Taito Osaka, Jan-Etienne Pudell, Weilun Qin, Nina Rohringer, Angel Rodriguez-Fernandez, Daniele Ronchetti, Yasuhisa Sano, Matthias Scholz, Roman Shayduk, Jergus Strucka, Yanwen Sun, James Wrigley, Kazuto Yamauchi, Diling Zhu, Alexey Zozulya, Makina Yabashi, Anders Madsen, Jumpei Yamada, Jiawei Yan
Medical Physics · Cross-listed from cs.CV
HERMES: A Hybrid Ensemble for Head-and-Neck Tumor Segmentation, TN Staging, and Recurrence-Free Survival on PET/CT
Kai Wang, Meixu Chen, Elie Nasr et al. (+2 more)
We present HERMES (Hybrid Ensemble for Radiotherapy-target
segmentation, Malignancy staging, and Event-free Survival), a single containerized
algorithm for the three HECKTOR 2026 subtasks:
segmentation of the primary tumor (GTVp) and pathological lymph nodes (GTVn), radiological T/N staging, and recurrence-free survival (RFS), computed from a paired FDG-PET/CT scan and an electronic health record. A 10-fold ensemble of STU-Net Small networks produces the
segmentation; the predicted mask then drives two downstream tasks. Rather than pass a generic radiomics vector to the staging models, we derive from the predicted masks a compact set of geometry features aligned with the size and number axes of AJCC/UICC 7th-edition radiological N/T staging. On internal cross-validation these features raise N-stage balanced accuracy from 0.691 to 0.720 (+0.030), our largest single design gain, at lower feature dimensionality. For prognosis we combine complementary deep and clinical risk experts in an equal-weight ensemble, and train one deep expert with a concordance-tracking survival loss of our own, whose value approximates the concordance index during training. Every component was selected on honest out-of-fold predictions under a regularization-oriented protocol, with no tuning on the public validation set, and deployed as two decorrelated submissions. On the HECKTOR 2026 validation leaderboard, HERMES achieved a weighted score of 0.6454 (Mean Dice 0.641, T balanced accuracy 0.580, N balanced accuracy 0.642, RFS C-index 0.679) and qualified for the testing phase. Team: AMC_HNC.
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All authors Kai Wang, Meixu Chen, Elie Nasr, Ryan Lanning, Moyed Miften
Plasma Physics
Revisiting Electron Heating in Capacitively Coupled Plasma (CCP) Discharges: A Nonlinear Dynamics Perspective
Rishabh Singh, Sarveshwar Sharma, Bhooshan Paradkar et al. (+1 more)
Despite decades of research, the electron heating mechanisms in capacitively coupled
plasma (CCP) discharges over a wide range of operating conditions is not fully understood. Although
stochastic heating is generally regarded as the dominant collisionless heating mechanism at low pressures, the inherently nonlinear electron dynamics responsible for this process have not been fully quantified. These nonlinear interactions drive
stochastic heating, a mechanism considered crucial for energy transfer in CCPs, yet its quantitative impact on
plasma parameters remains insufficiently explored. In this work, we investigate electron dynamics in steady-state CCP discharges and demonstrate that electron motion in the
plasma bulk exhibits intrinsically chaotic behavior. The onset of chaos is identified using Poincare sections and quantified through Lyapunov exponent analysis. To further quantify this behavior, we map the spatial distribution of the Lyapunov exponent-normalized by the electron-neutral collision frequency-across the
plasma bulk for different pressures and RF voltages. The normalized Lyapunov exponent increases systematically with decreasing pressure and increasing RF voltage, indicating enhanced stochasticity and a stronger sensitivity of electron trajectories to initial conditions. These results establish the Lyapunov exponent as a quantitative measure of effective
stochastic scattering in collisionless CCPs and provide a direct comparison with the classical
stochastic collision frequency proposed by Popov and Godyak [Journal of Applied Physics 57, 53-58 (1985)]. The present analysis offers a unified nonlinear dynamical framework for understanding
stochastic electron heating in low-pressure RF
plasmas.
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All authors Rishabh Singh, Sarveshwar Sharma, Bhooshan Paradkar, Sudip Sengupta
Optics · Cross-listed from quant-ph
Quantum random number generation using spatial quantum noise of light
Mohamed Armoon Shaliq and Ashok Kumar
Generating high-speed, verifiable random numbers is a fundamental requirement for cryptography, large-scale
stochastic simulations, and secure
quantum communication. Here, we present a robust
quantum random number generator that utilizes the spatial distribution of
quantum fluctuations captured by an electron-multiplying charge-coupled device operated in high-speed kinetic mode. Through rigorous detector calibration and shot-noise analysis, we characterize the spatial
quantum noise obtained from the spatial intensity fluctuations of the coherent states of light. Such
quantum noise serves as a high-
entropy source, enabling an instantaneous random bit generation rate of 5.92 Gbps without algorithmic randomness extraction in the present configuration. The sustained output rate is, however, limited to 7.5 Mbps by the bandwidth of the serial electronic readout. The generated sequences successfully pass the NIST SP 800-22 and Marsaglia Diehard statistical test suites, confirming the high quality and unpredictability of the
entropy source.
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Plasma Physics
Kinetic Optimization of Magnetic Mirror Confinement: Beyond Classical Loss-Cone Theory
Lukas Einkemmer, Martin Guerra, Qin Li et al. (+1 more)
Magnetic mirrors are among the conceptually simplest
plasma confinement configurations and remain promising candidates for thermonuclear fusion. Their design requires shaping an externally applied
magnetic field to confine
plasma within an open-ended cylindrical device. In contrast to toroidally closed devices such as tokamaks and stellarators, confinement in
magnetic mirrors depends intrinsically on kinetic mechanisms, particularly velocity-space trapping and particle loss through the open ends. We formulate
magnetic mirror design as a PDE-constrained optimization problem governed by a reduced multispecies drift-kinetic-Poisson model. The resulting optimization reveals two physical effects not captured by the classical loss-cone argument. First, the self-consistent electric field generated through Poisson coupling acts as a secondary confinement barrier and substantially alters particle retention in the nonlinear regime. Second, the optimized
magnetic-field configuration depends qualitatively on the underlying kinetic model: an electron-only model favors an unconventional centrally peaked field, whereas the fully coupled electron-ion model recovers the classical boundary-peaked mirror configuration. These results demonstrate that optimal
magnetic mirror design cannot be determined solely from loss-cone considerations, but must account for the self-consistent nonlinear kinetic dynamics of the
plasma.
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All authors Lukas Einkemmer, Martin Guerra, Qin Li, Leonardo Zepeda-Núñez
Fluid Dynamics
Prediction of Spherical Bubble-Chain-Induced Liquid Flow through Far-Wake Superposition Based on Bubble-Chain Hydrodynamics
Satoi Suzuki, Hiroaki Kusuno and Toshiyuki Sanada
Recent experimental observations revealed that clean spherical bubble chains generate a nearly uniform upward
liquid flow. The physical origin of this
liquid flow, however, remains unclear. Hydrodynamic interactions in aligned bubble chains were therefore investigated using high-accuracy embedded-boundary simulations that resolve the interfacial boundary layer while capturing long-range interactions among multiple clean spherical bubbles. The simulations were used to quantify the
evolution of hydrodynamic interactions within bubble chains and to identify the conditions under which bubble-induced
liquid flow can be represented by the superposition of isolated-bubble far wakes. Based on these findings, a reduced-order model was developed and applied to experimentally measured bubble trajectories. The model successfully reproduced the nearly uniform upward
liquid flow observed in the experiments. To clarify the role of bubble dispersion, the predictions were compared with those for a uniformly dispersed bubble arrangement having the same overall dispersion width. While the uniformly dispersed arrangement produced a center-peaked velocity distribution, only the experimentally observed bubble trajectories reproduced the nearly uniform upward
liquid flow. These results demonstrate that the
liquid flow is governed not simply by the dispersion width but by the bubble trajectories that establish the spatial distribution of far wakes. The present study provides a physical framework linking hydrodynamic interactions among bubbles, bubble dispersion, and bubble-induced
liquid flow, together with a reduced-order model for predicting the
liquid flow generated by bubble chains.
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Plasma Physics
Observation of poloidal magnetic flux emission from a low-pressure spark: validation of the hypothesis of constrained plasma dynamics?
A.B.Blagoev, V.Yordanov and S.K.H.Auluck
This paper revisits an earlier discussion of the hypothesis of constrained dynamics [IEEE Trans.
Plasma Sci. 41, 2013 pp. 437-446] with better experiments and insights. This hypothesis pertains to the observation that the standard single fluid equation of motion of a current-carrying
plasma has terms governed by diverse physical phenomena which are constrained to evolve at widely mismatched characteristic space and time scales. It should then be possible to construct counterexamples where the equation cannot be satisfied at all times. The hypothesis posits that the usually neglected electron inertia terms come into play in such examples and create "anomalous" electron currents whose signatures can be detected outside the
plasma. One of these signatures is emission of poloidal
magnetic flux not attributable to a helical deformation of the current channel. Following the cue of the above-mentioned paper, a series of low-pressure spark experiments have been performed. Clockwise and counterclockwise diamagnetic loops, an electrostatically shielded
magnetic probe oriented to intercept the azimuthal
magnetic flux and an electric displacement probe are deployed outside the spark channel. Observation of several expected signatures provides a tentative validation of this hypothesis. This suggests that summary neglect of electron inertia in continuum models of
plasma needs to be replaced by a redevelopment of these models based on perturbation theory with an electron-mass-related small parameter. Major insights could then arise into unsolved problems such as the origin of axial
magnetic field in astrophysical jets. Near-solid-density magneto-inertial confinement fusion may be a potential practical application.
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Applied Physics · Cross-listed from cond-mat.mes-hall
Asymmetric Floquet-Engineered Mode Coupling in Hybrid Magnonics
Amin Pishehvar, Jayakrishnan M. P. Nair, Zixin Yan et al. (+3 more)
In hybrid magnonic systems, linear
magnon–
photon hybridization inherently produces symmetric, reciprocal interactions, precluding asymmetric mode coupling. Floquet driving can tailor mode coupling strengths but, with single-tone modulation, inevitably generates a symmetric interaction that preserves this reciprocity. Here we introduce dual-tone Floquet modulation to unlock a new degree of freedom in hybrid magnonic systems, where the relative phase $\theta$ of two commensurate drives continuously controls the asymmetry of the Floquet-engineered interaction, enabling asymmetric mode coupling absent in existing hybrid magnonic systems. We demonstrate this in a strongly coupled cavity magnonic device, where tuning $\theta$ reversibly switches single-sided Autler–Townes splitting between the two hybrid modes—a direct spectroscopic signature of phase-programmable asymmetric coupling. This approach opens a new path toward controllable nonreciprocal and topological functionalities in hybrid magnonic systems, with broad implications for advanced
quantum and classical signal processing.
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All authors Amin Pishehvar, Jayakrishnan M. P. Nair, Zixin Yan, Yu Jiang, Benedetta Flebus, Xufeng Zhang
Atomic and Molecular Clusters · Cross-listed from quant-ph
Molecular triplets and other metastable states for excitonic quantum batteries
Daniel Tibben, Gian Marcello Andolina, Daniel E. Gómez et al. (+1 more)
Excitonic
quantum batteries, based on organic fluorescent molecules embedded in optical microcavities, offer a room-temperature platform for studying collective effects in energy storage and developing applications. Recent experiments have offered evidence of superabsorption, a collective enhancement to the light absorption rate of organic molecules which leads to a scalable power density. However, they have also highlighted the challenge posed by rapid radiative decay of fluorescent molecules, which limits the energy storage lifetime. Current strategies to overcome this trade-off focus on controlling the coupling between the absorbing
manifold and that used for energy storage. In this chapter, we review three implementations of this design principle: transferring energy from optically excited states to long-lived dark triplet states, generating triplet pairs and higher-
spin states through singlet
exciton fission, and forming charge-separated states. We discuss each mechanism from both theoretical and experimental perspectives, with particular emphasis on recent device implementations that have extended storage times by several orders of magnitude. We conclude with a cross-platform outlook on the role of metastable states across coherent and room-temperature implementations, from neutral atom arrays to masers and colour centres.
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All authors Daniel Tibben, Gian Marcello Andolina, Daniel E. Gómez, Francesco Campaioli
Optics
Addressing rotational motion on gravitational waves detectors
Chiara Di Fronzo and Jian Liu
The rotational components of Earth's seismic motion are one of the major contributions to limit the sensitivity of terrestrial gravitational-wave detectors at frequencies below 10 Hz. The fundamental challenges lie in understanding the angular degrees of freedom of seismic motion and how they can be accurately measured. These are both crucial steps for developing an adequate control system to suppress seismic motion and maintaining resonance in the detector cavities. This review shows why the rotational ground motion limits the detector's sensitivity and gives an overview of the technological achievements of the last decade on both the sensing and control systems sides. Perspectives on future developments in the field are also briefly illustrated.
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Data Analysis and Statistics · Cross-listed from stat.ML
Origins and mitigation of double descent in reduced order modeling
Andrei A. Klishin, J. Nathan Kutz and Krithika Manohar
Latent low-dimensional structure in
datasets of natural and engineered systems enables their sparse sensing, or full-state reconstruction from historical data and very few carefully chosen localized measurements. Depending on the reconstruction
algorithm, sensor locations, and measurement noise, the reconstruction risk curves demonstrate a diversity of patterns including a dramatic peak in error known as double descent in Machine Learning literature. Here we explore those scenarios under a unified Data-Noise Averaging theory. Qualitatively, we formulate sufficient criteria for double descent to emerge through a catastrophic amplification of a pathological signal in reconstruction. Quantitatively, we predict the detailed risk curves at a fraction of computational cost, trace reconstruction instability to individual sensors and their combinations, and provide regularization mechanisms to mitigate the instability. We demonstrate results for both static reconstruction of Sea Surface Temperature patterns and time integration of a reduced order model of a PDE.
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Plasma Physics
Phase control of multi-photon electron-positron pair creation from vacuum
C. K. Li, X. X. Zhou, B. An et al. (+3 more)
We investigate the creation of electron-positron pairs by two spatiotemporally inhomogeneous electric fields with a relative phase, employing computational
quantum field theory. We find that, when the two fields are closely spaced, the pair yield exhibits a cosine-like dependence on the relative phase. This suggests that the relative phase provides an effective way to enhance multi-
photon transition channels. Furthermore, our analysis reveals that the response of pair-creation channels to the relative phase changes substantially with the
photon order of the transition. For one-
photon transitions, the rate exhibits a $2\pi$ periodicity, whereas a reduced periodicity of $\pi$ is observed for two-
photon transitions. To clarify the underlying mechanism, we map the
quantum field-theoretical framework onto a time-dependent perturbation approach. By extending this approach to $n$-
photon processes, we show that the transition probability is periodic in the relative phase with period $2\pi/n$. This observation suggests that the relative phase offers an effective means of identifying the order of multi-
photon transitions.
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All authors C. K. Li, X. X. Zhou, B. An, Y. J. Li, N. S. Lina, Y. Wan
Optics
Self-similar rigid rotation in anisotropic squeezed Laguerre–Gaussian beams
D. Aguirre-Olivas, G. Mellado-Villaseñor and B. M. Rodriguez-Lara
We introduce anisotropic squeezed Laguerre–Gaussian beams as an analytically complete family of structured paraxial scalar beams with Gouy-phase-controlled rigid rotation. Our construction organizes the Laguerre–Gaussian transverse modal
Hilbert space into circular modal subspaces carrying parity-resolved single-mode $\mathrm{su}(1,1)$ representations. The resulting optical Bargmann bases support squeezed states whose lowest-weight forms factor into Gaussian beam phases, parity-dependent
polynomials, and elliptically anisotropic Gaussian envelopes. Excited seeds are
polynomial deformations of the same squeezed envelope, extending the analytic construction to the full family. The Gouy-dressed squeezing parameter sets the semi-axis widths, aspect ratio, handedness, and orientation, while propagation rotates the profile by the accumulated Gouy phase without changing the scaled transverse shape. We generate these fields with synthetic phase holograms and experimentally confirm their self-similar rigid rotation. Our scalar-beam family provides a tunable anisotropic structured-light platform whose transverse orientation encodes propagation distance and may support axial localization, range finding, optical manipulation, and modal diagnostics.
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