Physics Education
Exploring the potential of ChatGPT for feedback and evaluation in experimental physics
Marcos Abreu, Álvaro Suárez, Cecilia Stari et al. (+1 more)
This study explores how generative artificial intelligence, specifically ChatGPT, can assist in the evaluation of laboratory reports in Experimental Physics. Two interaction modalities were implemented: an automated API-based evaluation and a customized ChatGPT configuration designed to emulate instructor feedback. The analysis focused on two complementary dimensions-formal and structural integrity, and technical accuracy and conceptual depth. Findings indicate that ChatGPT provides consistent feedback on organization, clarity, and adherence to scientific conventions, while its evaluation of technical
reasoning and interpretation of experimental data remains less reliable. Each modality exhibited distinctive limitations, particularly in processing graphical and mathematical information. The study contributes to understanding how the use of AI in evaluating laboratory reports can inform feedback practices in experimental physics, highlighting the importance of teacher supervision to ensure the validity of physical
reasoning and the accurate interpretation of experimental results.
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All authors Marcos Abreu, Álvaro Suárez, Cecilia Stari, Arturo C. Marti
Atomic Physics
Unravelling inter-channel quantum interference in below-threshold nonsequential double ionization with statistical measures
S. Hashim and C. Figueira de Morisson Faria
We present a systematic study of interchannel
quantum interference in
laser-induced nonsequential double ionization (NSDI) within the strong-field approximation. Focusing on the below-threshold intensity regime where the recollision-excitation with subsequent ionization (RESI) pathway dominates, we derive analytical phase conditions governing interference between distinct excitation channels for arbitrary driving fields. To quantify the interplay between channels resulting from a vast number of interfering processes, we introduce statistical metrics based on the Earth Mover's Distance, allowing us to assess the relative weight of each channel's contribution to the two-electron photoelectron momentum distributions (PMDs). We identify key factors that determine whether interchannel interference is appreciable such as comparable channel intensities, strong spatial overlap between the excited-state wavefunctions and the energy difference between contributing channels. We demonstrate that for linearly polarized few-cycle pulses, the typical intrachannel interference features associated with exchange, temporal shifts and combined exchange-temporal interference are retained with interchannel interference. Our findings establish a hierarchy of interference mechanisms in RESI and may provide practical guidelines for enhancing or suppressing interference in different regions of the momentum plane. The toolkit presented in this work is transferable to a wide range of interferometric schemes involving different excitation channels.
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Applied Physics · Cross-listed from cond-mat.mes-hall
Deterministic nanofabrication of quantum dot-circular Bragg grating resonators with high process yield using in-situ electron beam lithography
Avijit Barua, Kartik Gaur, Leo J. Roche et al. (+5 more)
The controlled integration of
quantum dots (QDs) as single-
photon emitters into
quantum light sources is essential for the implementation of large-scale
quantum networks. In this study, we employ the deterministic in-situ electron-beam lithography (iEBL) nanotechnology platform to integrate individual QDs with high accuracy and process yield into circular Bragg grating (CBG) resonators. Notably, CBG devices comprising just 3 to 4 rings exhibit
photon extraction efficiencies comparable to those of structures with more rings. This facilitates faster fabrication, reduces the device footprint, and enables compatibility with electrical contacting. To demonstrate the scalability of this process, we present results of 95 optically active QD-CBG devices fabricated across two lithography sessions. These devices exhibit bright, narrow-linewidth single-
photon emission with excellent optical quality. To evaluate QD placement accuracy, we apply a powerful characterization technique that combines cathodoluminescence (CL) mapping and scanning electron microscopy. Statistical analysis of these devices reveals that our iEBL approach enables high
alignment accuracy and a process yield of over >90% across various CBG geometries. Our findings highlight a reliable route toward the scalable fabrication of high-performance QD-based single-
photon sources for use in photonic
quantum technology applications.
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All authors Avijit Barua, Kartik Gaur, Leo J. Roche, Suk In Park, Priyabrata Mudi, Sven Rodt, Jin-Dong Song, Stephan Reitzenstein
Optics · Cross-listed from cs.LG
Near-Equilibrium Propagation training in nonlinear wave systems
Karol Sajnok and Michał Matuszewski
Backpropagation learning
algorithm, the workhorse of modern artificial intelligence, is notoriously difficult to implement in physical neural networks.
Equilibrium Propagation (EP) is an alternative with comparable efficiency and strong potential for in-situ training. We extend EP learning to both discrete and continuous complex-valued wave systems. In contrast to previous EP implementations, our scheme is valid in the weakly dissipative regime, and readily applicable to a wide range of physical settings, even without well defined nodes, where trainable inter-node connections can be replaced by trainable local potential. We test the method in driven-dissipative
exciton-polariton condensates governed by generalized Gross-Pitaevskii dynamics. Numerical studies on standard
benchmarks, including a simple logical task and handwritten-digit recognition, demonstrate stable convergence, establishing a practical route to in-situ learning in physical systems in which system control is restricted to local parameters.
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Computational Physics
Boundary-Informed Method of Lines for Physics Informed Neural Networks
Maximilian Cederholm, Siyao Wang, Haochun Wang et al. (+2 more)
We propose a hybrid solver that fuses the dimensionality-reduction strengths of the Method of Lines (MOL) with the flexibility of Physics-Informed Neural Networks (PINNs). Instead of approximating spatial derivatives with fixed finite-difference stencils - whose truncation errors force extremely fine meshes - our method trains a neural network to represent the initial spatial profile and then employs automatic differentiation to obtain spectrally accurate gradients at arbitrary nodes. These high-fidelity derivatives define the right-hand side of the MOL-generated ordinary-differential system, and time integration is replaced with a secondary temporal PINN while spatial accuracy is retained without mesh refinement. The resulting "boundary-informed MOL-PINN" matches or surpasses conventional MOL in accuracy using an order of magnitude fewer collocation points, thereby shrinking
memory footprints, lessening dependence on large data sets, and increasing complexity robustness. Because it relies only on automatic differentiation and standard optimizers, the framework extends naturally to linear and nonlinear PDEs in any spatial dimension.
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All authors Maximilian Cederholm, Siyao Wang, Haochun Wang, Ruichen Xu, Yuefan Deng
Optics
Directional and contra-directional coupling in Huygens' metawaveguide microring resonators
M. Saad Bin-Alam, Yunus Denizhan Sirmaci, Alejandro Fernández-Hinestrosa et al. (+8 more)
Huygens' metawaveguides represent a transformative concept in photonic device engineering, enabling unprecedented control over light propagation. This study presents, for the first time, integrated Huygens'-based microring resonators and directional and contra-directional couplers, specifically designed for operation at the S- and C-band telecommunication wavelengths. By leveraging the unique properties of resonant Huygens' waveguides, we demonstrate efficient evanescent directional coupling with high-Q resonators, characterized by negative group index and near-zero dispersion, which are critical for enhancing performance in compact, high-performance add-drop filters. The research further explores the implications of these novel structures on group index and group velocity dispersion, providing insights into their potential applications in nonlinear optics and
quantum information technologies. Notably, the introduction of a hybrid subwavelength grating-Huygens' contra-directional coupler facilitates backward coupling between resonant and non-resonant metawaveguides, achieving a broad spectral rejection bandwidth. Our findings advance the integration of resonant metamaterials into scalable photonic platforms, laying the groundwork for innovative applications in optical communications,
quantum photonics and sensing systems.
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All authors M. Saad Bin-Alam, Yunus Denizhan Sirmaci, Alejandro Fernández-Hinestrosa, Jianhao Zhang, Ksenia Dolgaleva, Robert W. Boyd, José Manuel Luque-González, Thomas Pertsch, Isabelle Staude, Jens H. Schmid, Pavel Cheben
Applied Physics · Cross-listed from gr-qc
Aiming for Proxima Centauri b: Gravitational effects on relativistic spacecraft trajectories
Mark C. Baumann, Justin C. Feng and Nicky Ishaak
How important are gravitational and relativistic effects for interstellar travel? We consider this question in the context of proposed
laser-propelled spacecraft missions to neighboring
stellar destinations. Our analysis applies to any spacecraft traveling at relativistic speeds. As a concrete example, we focus on a mission to Proxima Centauri b – a terrestrial-sized
planet in the habitable zone around our nearest
stellar neighbor, Proxima Centauri. We employ a Julia reimplementation of the PoMiN code, an N-body code modeling relativistic gravitational dynamics in the first post-Minkowskian (PM) approximation to general relativity (valid to linear order in Newton's constant $G$). We compute the gravitational influence of seven different celestial bodies and find that the Sun has the greatest influence on the trajectory of the interstellar spacecraft. We also study the differences between Newtonian and PM
gravity, and find that if mission planners wish to hit Proxima Centauri b with an accuracy of better than about 690,000 kilometers, relativistic effects must be taken into account. To solve for the precise initial data needed to hit an intended target, we develop numerical fine-tuning methods and demonstrate that these methods can (within a given model) be precise to about a femtometer over a travel distance of $\sim4.25$ light years. However, we find that for the spacecraft trajectories we consider, higher order general relativistic effects (beyond the first PM approximation) from the Sun can displace the final position of the spacecraft by tens of kilometers. We also consider the variation in the initial direction of the spacecraft velocity and find that, even with relativistic effects properly taken into account, the miss distances can be dominated by the variation in the initial velocity that could arise from errors during the launch and boost phase of the spacecraft mission.
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Fluid Dynamics · Cross-listed from math.NA
Longer time accuracy for the Ladyzhenskya model with the EMAC formulation
Rihui Lan and Jorge Reyes
In this paper, we incorporate the EMAC formulation into the Ladyzhenskaya model (LM), a large eddy simulation (LES) of incompressible flows. The EMAC formulation, which conserves energy, linear momentum, and angular momentum even with weak enforcement of incompressibility, has been shown to provide tangible benefits over the popular skew-symmetric for direct numerical simulation and regularized models of the Navier Stokes equations (NSE). The combination of EMAC with the LM addresses the known over-dissipation issues associated with the classical Smagorinsky model (SM). We develop a finite element discretization for the EMAC-LM system and analyze its stability and derive numerical error estimates, showing improved long-time behavior compared to the standard LM approach, particularly due to EMAC's favorable Gronwall constant independent of the Reynolds number.
Benchmark simulations demonstrate that the EMAC-LM model yields more accurate flow structures, especially at high Reynolds numbers.
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Accelerator Physics
Compensating for Amplifier Non-Linearity in a SEL Controller
S. Raman, P. Varghese, L. Reyes et al. (+4 more)
The Self-Excited Loop (SEL) architecture, used in some continuous-wave (CW) superconducting linacs, relies on a positive feedback mechanism that requires carefully defined operating limits to ensure stable operation. These limits are typically derived from amplifier calibration, which characterizes the relationship between forward power and DAC drive. However, amplifier non-linearity often prevents a simple linear fit of this characteristic, introducing errors that can compromise stability. To address this, we present a modified calibration procedure that incorporates amplifier non-linearity into the SEL framework. The approach is validated with test data from a 32 kW solid-state amplifier (SSA) and a cavity emulator developed for the Fermilab PIP-II linac.
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All authors S. Raman, P. Varghese, L. Reyes, M. Guran, L. Doolittle, S. Murthy, Q. Du
Chemical Physics · Cross-listed from quant-ph
Operator Commutativity Screening and Progressive Operator Block Reordering toward Many-body Inspired Quantum State Preparation
Dibyendu Mondal, Debaarjun Mukherjee and Rahul Maitra
In the field of
quantum chemistry, the variational
quantum eigensolver (VQE) has emerged as a highly promising approach to determine molecular energies and properties within the noisy intermediate-scale
quantum (NISQ) era. The central challenges of this approach lie in the design of an expressive ansatz capable of representing the exact ground state wavefunction while concurrently being efficient to avoid numerical instabilities during the classical optimization. Owing to the constraints of current
quantum hardware, the ansatz must remain sufficiently compact while retaining the flexibility to capture essential correlation effects. To address these challenges, we propose a systematic dynamic ansatz construction strategy in which the dominant operator blocks are initially identified through commutativity screening, combined with an energy sorting criteria. Subsequently, the ansatz is progressively expanded in a stepwise manner via iterative operator block reordering. To minimize the overhead, the higher order correlation terms are incorporated via reduced lower-body tensor factorization in each operator block, while the adaptive construction strategy ensures that the optimization is guided along the optimal trajectory to mitigate potential numerical instabilities due to the presence of local traps.
Benchmark applications to various molecular systems demonstrate that this strategy of progressive operator-block addition achieves accurate energetics with significantly fewer parameters while efficiently bypassing local traps. Moreover, in strongly correlated regions, such as bond dissociation, the method successfully reproduces the ground state, where other contemporary approaches often fail.
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Physics Education
Peer Influence on Physics Self-Efficacy and Grades: A comparative study of students in an introductory calculus-based course who typically worked alone or in groups before and during the pandemic
Apekshya Ghimire and Chandralekha Singh
Engaging in meaningful collaborations with peers, both inside and outside the classroom, can greatly enhance students' understanding of physics and other STEM disciplines. We analyzed the characteristics of women and men who typically worked alone versus those who collaborated with peers in a calculus-based introductory physics course comparing pre pandemic traditional in-person classes to Zoom based pandemic classes. We discuss our findings by considering students' prior academic preparation, their physics grades and physics self-efficacy, as well as their perceptions of how effective peer collaboration is for their physics self-efficacy. We also compared our results to the first-semester
algebra-based introductory physics course.
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Physics Education
Investigating High School and Pre-High School Teachers' Perceptions and Experiences Introducing Quantum Concepts: A Survey of QuanTime and other Quantum-related Activities
Apekshya Ghimire, Jaya Shivangani Kashyap, Emily Edwards et al. (+2 more)
This study investigates the experiences of pre-high and high school teachers in implementing QuanTime and other
quantum-related activities aiming to promote
quantum literacy and introduce foundational
quantum concepts to K-12 students. The ultimate goal is to help prepare a diverse future workforce in
quantum information science and technology (QIST). Teachers were divided into two groups: pre-high school (grades 4-8) and high school (grades 9-12). We used a survey featuring 12 Likert-scale questions and 14 open-ended responses to assess teachers' perceptions, engagement, and feedback about engaging in QuanTime and other
quantum-related activities. Approximately two-thirds of the teachers responding to the survey implemented QuanTime activities in their classes. High school teachers who responded to the survey were most likely to use activities like Wave-Particle Duality and Electron Transitions while pre-high school teachers showed a strong interest in Art & Polarization. Open-ended feedback highlighted the ease of integrating these activities into existing curricula and the minimal preparation required, making them accessible for educators. The positive reception across both groups indicates that QuanTime and other
quantum-related activities are valuable tools for early-age
quantum education. By engaging students with
quantum concepts from a young age, these activities have the potential to spark interest, which may contribute to their future engagement over time. It can inspire a diverse group of students and has the potential to get them interested in future opportunities in the growing field of QIST.
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All authors Apekshya Ghimire, Jaya Shivangani Kashyap, Emily Edwards, Diana Franklin, Chandralekha Singh
Geophysics
Multiphysics inversion with variable complexity of receiver-function, surface-wave dispersion and magnetotelluric data reduces uncertainty for lithosphere structure
P. Shahsavari, J. Dettmer, M.J. Unsworth et al. (+1 more)
We present a probabilistic multiphysics inversion based on
Bayesian inference with trans-dimensional models. We jointly consider magnetotelluric, receiver function, and Rayleigh-wave dispersion data to infer one-dimensional lithospheric structure in the vicinity of Athabasca, Canada. The location is on the North American Craton with a cover of sediments from the Western Canada Sedimentary Basin. The trans-dimensional model uses layer nodes that include parameters that are activated or deactivated based on data information. Furthermore, the number of nodes is based on data information. Hence, the parameterization uncertainty is included in the uncertainty estimates. Furthermore, the layer nodes permit trans-dimensional decoupling such that some discontinuities may be represented by only some of the parameters. In probabilistic multiphysics inversion, it is important that the various data types are weighed objectively. Here, the weights are the data covariance
matrices of the various data types. We apply empirical estimation of data covariance
matrices and employ hierarchical scaling parameters to reduce the dependence on some assumptions required by the empirical approach. Hence, we account for noise variances and covariances, which is crucial for successful probabilistic multiphysics inversion. The parameter estimates and data covariance
matrices are obtained with the reversible-jump Markov chain Monte Carlo
algorithm with parallel tempering to enhance the efficiency. Since covariance
matrix estimation changes data weights, the estimation process is carried out while samples are not recorded for inference. The results at the Athabasca site fit the data and produce plausible data covariance
matrices for the data weights.
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All authors P. Shahsavari, J. Dettmer, M.J. Unsworth, A. Schaeffer
Applied Physics
Non-uniform pneumatic actuation switches macroscopic properties of elastomeric honeycombs
Ondřej Faltus, Martin Doškář, Jan Havelka et al. (+2 more)
Honeycomb microstructures with circular voids are well known to undergo pattern transformations under macroscopic strain loading. Depending on the biaxiality of the applied strain, they deform into three different patterns. Here we demonstrate that the same three patterns can be triggered also by pneumatic actuation of the voids, with resulting patterns depending on an applied pressurization scheme, i.e., the ratio of suction pressures introduced in different voids within the microstructure. Our numerically obtained findings are experimentally validated on two finite size samples made of silicone rubber cast in a 3D printed mold. In numerical studies, we first showcase the
evolution of homogenized stiffness and its anisotropy during the genesis of pneumatically-induced patterns. Our loading schemes result in macroscopic stiffness varying by a factor of two with loading direction, chosen by a reversible actuation independent of the load itself. Second, we study the effect of the pneumatic actuation on acoustic properties of the microstructure, finding the proposed method viable to trigger different acoustic bandgaps.
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All authors Ondřej Faltus, Martin Doškář, Jan Havelka, Pavel Rychnovský, Ondřej Rokoš
Applied Physics
Integration of Porous Graphene and 3D-printed Piezopolymer for Flexible Ultrasound Transducers
Shirin Movaghgharnezhad, Ehsan Ansari, Clayton A Baker et al. (+4 more)
Ultrasound technology is crucial in diagnostic imaging, making it widely used in medical applications. However, traditional ultrasound transducers face limitations in flexibility and ease of fabrication, leading to the exploration of thin-film and flexible piezoelectric materials. Here, we present a novel approach that combines
laser graphitization with 3D printing to integrate flexible
laser-induced porous
graphene (LIG) with poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE), resulting in the development of flexible LIG/PVDF-TrFE ultrasound patches. The thickness of PVDF-TrFE is adjusted to tune the central frequency of the ultrasound transducer, allowing customization within a range of 10 to 28 MHz. LIG-based ultrasound transducer demonstrates a high signal amplitude of 6.72 V and a signal-to-noise ratio (SNR) of 433, along with a -6 dB bandwidth of 8.86 MHz (37%). The LIG-based transducer exhibits higher acoustic performance compared to the smooth silver-based transducer. A high-quality two-dimensional ultrasound image, including a B-mode image of a cyst phantom, demonstrates the transducer's imaging capabilities. The patterning of LIG-based electrodes facilitates the desired sensor configuration, demonstrating the suitability of our novel technique for producing flexible transducer arrays without dicing and cutting. The materials cost of our LIG/PVDF-TrFE transducer is under $5 per unit, making it a low-cost solution for ultrasound patches.
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All authors Shirin Movaghgharnezhad, Ehsan Ansari, Clayton A Baker, Ahmed A Bashatah, Dulcce A Valenzuela, Pilgyu Kang, Parag V Chitnis
Fluid Dynamics
A HHO formulation for variable density incompressible flows where the density is purely advected
Lorenzo Botti and Francesco Carlo Massa
We propose a Hybrid High-Order (HHO) formulation of the incompressible Navier-Stokes equations with variable density that provides exact conservation of volume and, accordingly, pure advection of the density variable. The spatial discretization relies on hybrid velocity-density-pressure spaces and the temporal discretization is based on Explicit Singly Diagonal Implicit Runge-Kutta (ESDIRK) methods. The formulation possesses some attractive features that can be fruitfully exploited for the simulation of mixtures of immiscible incompressible fluids, namely: conservation of volume enforced
cell-by-
cell up to machine precision, pressure-robustness, ability to preserve density bounds at low-order, robustness in the convection dominated regime, weak imposition of boundary conditions, implicit high-order accurate time stepping, reduced
memory footprint thanks to static condensation, possibility to exploit inherited $p$-multilevel solution strategies to improve the performance of iterative solvers. After addressing stability at the discrete level, numerical validation is performed showcasing spatial and temporal convergence rates. To conclude, we tackle the Rayleigh-Taylor instability at different Atwood and Reynolds numbers focusing on mesh independence capabilities.
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Optics · Cross-listed from quant-ph
Optomechanical crystal in light-resilient quantum ground state
Johan Kolvik, Paul Burger, David Hambraeus et al. (+4 more)
Interaction between light and high-frequency sound is a key area in integrated photonics,
quantum and nonlinear optics, and
quantum science. However, typical suspended optomechanical structures suffer from poor thermal anchoring, making them susceptible to thermal noise arising from optical absorption. Here, we demonstrate a chip-scale, release-free silicon optomechanical
crystal cavity operating cryogenically with improved resilience to
laser light. Relative to a suspended design, we observe 18 dB suppression of the thermo-optic effect, and the device also sustains near-unity
phonon occupation at 35 dB higher intracavity optical energy in continuous-wave operation. Non-exponential decay dynamics from an as yet unidentified thermal process limit transfer of this performance to pulsed operation. Resolving this channel would open a clear path to near-term
quantum protocols, such as microwave-to-optical
quantum transduction. More broadly, the release-free architecture offers a novel platform for studying thermal noise dynamics with results relevant across silicon optomechanical platforms.
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All authors Johan Kolvik, Paul Burger, David Hambraeus, Trond H. Haug, Joey Frey, Mads B. Kristensen, Raphaël Van Laer
Computational Physics · Cross-listed from quant-ph
Globalizing the Carleman linear embedding method for nonlinear dynamics
Ivan Novikau and Ilon Joseph
The Carleman
embedding method is a well-known technique for linearizing a system of nonlinear differential equations, but fails to converge in regions where there are multiple fixed points. We prove that the need for the solution to be expressible as a convergent Taylor series of the initial conditions leads to restrictions on the stability and convergence of the Carleman
algorithm. Inspired by this realization, we propose and test three different versions of a global piecewise Carleman
embedding technique, based on partitioning space into multiple regions where the center and size of the
embedding region are chosen to control convergence. The first method switches between local linearization regions of fixed size once the trajectory reaches the boundary of the current linearization chart. During the transition, the
embedding is reconstructed within the newly created chart, centered at the transition point. The second method also adapts the chart size dynamically, enhancing accuracy in regions where multiple fixed points are located. The third method partitions the state space using a static grid with precomputed linearization charts of fixed size, making it more suitable for applications that require high speed. All techniques are numerically tested on multiple integrable and chaotic nonlinear dynamical systems demonstrating their applicability for problems that are completely intractable for the standard Carleman
embedding method. Simulations of chaotic dynamical systems such as various types of strange attractors demonstrate the power of the adaptive methods. However, global Carleman methods face fundamental limitations when simulating chaotic nonlinear systems on
quantum computers due to overhead during nonlinear remapping.
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Atmospheric and Oceanic Physics · Cross-listed from eess.SY
Mitigating Underwater Noise from Offshore Wind Turbines via Individual Pitch Control
Martín de Frutos, Laura Botero-Bolívar and Esteban Ferrer
This paper proposes a pitch control strategy to mitigate the
underwater acoustic footprint of offshore wind turbines, a measure that will soon become necessary to minimize impacts on marine life, which rely on sound for communication,
navigation, and survival. First, we quantify the
underwater acoustic signature of blade-generated aerodynamic noise from three reference turbines, the NREL 5 MW, DTU 10 MW, and IEA 22 MW, using coupling blade element momentum and coupled air-water acoustic propagation modeling. Second, we propose and implement an open-loop individual pitch control (IPC) strategy that modulates the pitch of the blade at the blade passing frequency to attenuate the overall sound pressure level (OSPL) and the amplitude modulation (AM) of the transmitted noise. Third, we
benchmark IPC performance against conventional pitch schemes. The results indicate that up to 5 dB reductions in OSPL and a decrease in AM depth 20% can be achieved with a pitch variation of $\Delta\theta\approx 5^\circ$, with small losses (5-10%) in energy capture. These findings highlight a previously underappreciated noise pathway and demonstrate that targeted blade-pitch modulation can mitigate its impact.
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Optics
All-Dielectric Photo-thermo-optical Metasurfaces for Thermal Landscaping at the Nanoscale
Gopal Narmada Naidu, Omer Can Karaman and Giulia Tagliabue
Precise control of temperature fields at the micro- and nanoscale is essential for emerging applications in nanophotonics, catalysis, and microfluidics, yet remains difficult due to the diffusive nature of heat. While inverse-design
algorithms have advanced thermoplasmonic metasurfaces, their extension to all-dielectric systems has not been explored. Here, an inverse thermal design framework is introduced for dielectric metasurfaces composed of thermo-optical amorphous silicon (a-Si) nanoresonators. By leveraging a precomputed library of absorption spectra as a function of geometry and temperature, target thermal profiles are directly mapped onto metasurfaces, enabling both uniform and complex temperature shaping. Unlike plasmonic platforms that require multi-resonator unit
cells for tunability, dielectric nanoresonators provide intrinsic reconfigurability: at wavelengths where the thermo-optical coefficient is negligible (e.g., ~500 nm), absorption is temperature-invariant, whereas at other wavelengths it becomes strongly temperature-dependent, allowing illumination intensity to reshape the thermal landscape. This multifunctionality permits a single metasurface to yield distinct profiles under different excitation conditions without added structural complexity. As a proof of concept, photothermal catalysis on such metasurfaces is modeled, predicting over 30% enhancement in reaction rates. The presented framework establishes a scalable strategy for engineering nanoscale temperature fields with broad implications for catalysis, thermal management, and photothermal energy conversion.
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Optics
3D-Structured Polyethylene Windows for Low-Loss Transmission in Wideband Cryogenic Terahertz Systems
François Joint, Igor Lapkin, Pierre-Baptiste Vigneron et al. (+10 more)
We present the design, fabrication, and characterisation of a broadband
vacuum window and infrared filter based on ultra-high molecular weight polyethylene (UHMWPE) for millimeter wave receivers operating across ALMA Band 6 and 7 (211-373 GHz). The window incorporates pyramidal anti-reflection (AR) structures, machined directly into the polyethylene using CNC machining, which provide impedance matching over a broad frequency range. The structured UHMWPE method was implemented in two distinct components: a
vacuum window and a cryogenic infrared filter. This surface structuring approach provides mechanical robustness, cryogenic compatibility, and low insertion loss. We characterize the transmission properties using Terahertz Time-Domain Spectroscopy (THz-TDS), which demonstrates reflection below $5\%$ across the full band. Complementary heterodyne measurements confirm improved receiver noise performance. These results establish 3D structured UHMWPE as a promising platform for broadband cryogenic optics in high-sensitivity THz instrumentation.
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All authors François Joint, Igor Lapkin, Pierre-Baptiste Vigneron, Emilie Hérault, Denis Meledin, Alexei Pavolotsky, Magnus Strandberg, Sven Erik Ferm, Mathias Fredrixon, Leif Helldner, Erik Sundin, Victor Belitsky, Vincent Desmaris
Computational Physics · Cross-listed from stat.ME
Bayesian Inference for PDE-based Inverse Problems using the Optimization of a Discrete Loss
Lucas Amoudruz, Sergey Litvinov, Costas Papadimitriou et al. (+1 more)
Inverse problems are crucial for many applications in science, engineering and medicine that involve data assimilation, design, and imaging. Their solution infers the parameters or latent states of a complex system from noisy data and partially observable processes. When measurements are an incomplete or indirect view of the system, additional knowledge is required to accurately solve the inverse problem. Adopting a physical model of the system in the form of partial differential equations (PDEs) is a potent method to close this gap. In particular, the method of optimizing a discrete loss (ODIL) has shown great potential in terms of robustness and computational cost. In this work, we introduce B-ODIL, a
Bayesian extension of ODIL, that integrates the PDE loss of ODIL as prior knowledge and combines it with a likelihood describing the data. B-ODIL employs a
Bayesian formulation of PDE-based inverse problems to infer solutions with quantified uncertainties. We demonstrate the capabilities of B-ODIL in a series of synthetic
benchmarks involving PDEs in one, two, and three dimensions. We showcase the application of B-ODIL in estimating tumor concentration and its uncertainty in a patient's
brain from MRI scans using a three-dimensional tumor growth model.
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All authors Lucas Amoudruz, Sergey Litvinov, Costas Papadimitriou, Petros Koumoutsakos
Plasma Physics
Formation of a Tungsten Co-deposition Layer with Microparticles Using Pulsed Laser Deposition
S.Kodate, Y.Hayashi and S.Kajita
This study performed tungsten (W) co-deposition experiments using pulsed
laser deposition under exposure to helium/argon
plasma in a linear
plasma device. Micron-sized spherical W particles formed under co-deposition conditions. It was suggested that these particles grew from nanoparticles via the electrostatic collection of W ions in the
plasma plume before deposition.
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Biological Physics
Genesis of a Horizontal Electric Field within the Lipid Bilayer: A Bilayer-Embedded Actuation Platform
Maki Komiya, Madoka Sato, Teng Ma et al. (+19 more)
The electric field of biological membranes has long been treated as a one-dimensional quantity, defined solely by the component normal to the
bilayer (E_VERT). Here, we present a bioelectronic platform that enables controlled generation of a horizontal electric field within the hydrophobic core of a lipid
bilayer (E_HORZ). The device incorporates micrometer-scale electrodes embedded within the
bilayer torus, allowing sustained E_HORZ actuation. Applied E_HORZ selectively and reversibly accelerates slow inactivation of a voltage-gated potassium channel while leaving activation essentially unchanged. Physical considerations further indicate that E_HORZ arises naturally wherever membrane potential varies spatially, including at action potential wavefronts, suggesting broader physiological relevance. This platform provides experimental access to vector-resolved membrane electric fields and establishes a generalizable strategy for multidirectional electrical control of soft-matter biointerfaces.
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All authors Maki Komiya, Madoka Sato, Teng Ma, Hironori Kageyama, Tatsuya Nomoto, Takahisa Maki, Masayuki Iwamoto, Miyu Terashima, Daiki Ando, Takaya Watanabe, Yoshikazu Shimada, Daisuke Tadaki, Hideaki Yamamoto, Yuzuru Tozawa, Ryugo Tero, Albert Marti, Jordi Madrenas, Shigeru Kubota, Fumihiko Hirose, Michio Niwano, Shigetoshi Oiki, Ayumi Hirano-Iwata
Computational Physics · Cross-listed from cond-mat.mtrl-sci
Atomic cluster expansion potential for the Si-H system
Louise A. M. Rosset and Volker L. Deringer
The silicon-hydrogen system is of key interest for
solar-
cell devices, including both crystalline and amorphous modifications. Elemental amorphous Si is now well understood, but the atomic-scale effects of hydrogenating the silicon
matrix remain to be fully explored. Here, we present a machine-learned interatomic potential model based on the atomic cluster expansion (ACE) framework that can describe a wide range of Si-H phases, from crystalline and amorphous bulk structures to surfaces and molecules. We perform numerical and physical validation across a range of hydrogen concentrations and compare our results to experimental findings. Our work constitutes an advancement toward the exploration of large structural models of a-Si:H at realistic device scales.
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Physics and Society
Measuring nodes centrality when local and global measures overlap
Lorenzo Costantini, Carla Sciarra, Luca Ridolfi et al. (+1 more)
Centrality metrics aim to identify the most relevant nodes in a network. In literature, a broad set of metrics exists, either measuring local or global centrality characteristics. Nevertheless, when networks exhibit a high spectral gap, the usual global centrality measures typically do not add significant information with respect to the degree, i.e., the simplest local metric. To extract new information from this class of networks, we propose the use of the GENeralized Economic comPlexitY index (GENEPY). Despite its original definition within the economic field, the GENEPY can be easily applied and interpreted on a wide range of networks, characterized by high spectral gap, including monopartite and bipartite networks systems. Tests on synthetic and real-world networks show that the GENEPY can shed new light about the nodes centrality, carrying information generally poorly correlated with the nodes number of direct connections (nodes degree).
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All authors Lorenzo Costantini, Carla Sciarra, Luca Ridolfi, Francesco Laio
Optics
Ultracompact Low-Loss Grating Couplers
Shiang-Yu Huang, Jonas Zatsch, Tim Engling et al. (+2 more)
Fiber-to-chip couplers play a crucial role in interfacing on-chip photonic
circuits with other optical systems or off-chip devices. Downsizing the couplers via
topology optimization addresses the demand for high-density integration and improves the scalability of photonic integrated systems. However, these optimized couplers have yet to reach the performance level demonstrated by their conventional counterparts, leaving room for further improvement. In this work, we apply
topology optimization to design single-polarization 1D and dual-polarization 2D grating couplers incorporating bottom reflectors and achieve sub-decibel coupling efficiency. Both types of couplers are fabricated on the silicon-on-
insulator platform with dimensions of mere 14 $\mu$m $\times$ 14 $\mu$m and are compatible with standard single-mode fibers at normal incidence. From our experimental characterization, the measured peak coupling efficiency of the
topology-optimized 1D and 2D couplers is -0.92(1) dB and -0.86(13) dB, respectively, within the telecom C-band. Our demonstration provides a coupling solution for photonic applications requiring high efficiency and high-density integration, such as spatial division multiplexing and photonic
quantum technologies.
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All authors Shiang-Yu Huang, Jonas Zatsch, Tim Engling, Jeldrik Huster, Stefanie Barz
Applied Physics
Multiscale X-ray computed tomography of standard optical fibers
Maria Caterina Crocco, Flavio Cognigni, Alessia Sanna et al. (+12 more)
Optical fiber technologies enable high-speed communication, medical imaging, and advanced sensing. Among the techniques for the characterization of optical fibers, Xray computed
tomography has recently emerged as a versatile non-destructive tool for mapping their refractive index variations in 3D. In this study, we present a multiscale characterization of standard optical fibers. We carry out an intercomparison of three
tomography setups: classical computed microtomography, X-ray microscopy, and nanotomography. In each method, our analysis highlights the trade-offs between resolution, field of view, and
segmentation efficiency. Additionally, we integrate deep learning
segmentation thresholding to improve the image analysis process. Thanks to its large field of view, microtomography with classical sources is ideal for the analysis of relatively long fiber spans, where a low spatial resolution is acceptable. The other way around, nanotomography has the highest spatial resolution, but it is limited to very small fiber samples, e.g., fiber tapers and nanofibers, which have diameters of the order of a few microns. Finally, X-ray microscopy provides a good compromise between the sample size fitting the device's field of view and the spatial resolution needed for properly imaging the inner features of the fiber. Specifically, thanks to its practicality in terms of costs and cumbersomeness, we foresee that the latter will provide the most suitable choice for the quality control of fiber drawing in real-time, e.g., using the "One-Minute Tomographies with Fast Acquisition Scanning Technology" developed by Zeiss. In this regard, the combination of X-ray computed
tomography and artificial intelligence-driven enhancements is poised to revolutionize fiber characterization, by enabling precise monitoring and adaptive control in fiber manufacturing.
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All authors Maria Caterina Crocco, Flavio Cognigni, Alessia Sanna, Raffaele Filosa, Svetlana Siprova, Riccardo C. Barberi, Raffaele G. Agostino, Stefan Wabnitz, Antonio D'Alessandro, Sylvie Lebrun, Marco Rossi, Vincenzo Formoso, Roberto Termine, Alberto Bravin, Mario Ferraro
Atomic Physics
FSRCC two-valence calculations of clock transition properties, dipole polarizability and isotope shifts in Fermionic and Bosonic Sr
Palki Gakkhar, D Angom and B K Mani
We employ an all-particle multireference Fock-space relativistic coupled-cluster (FSRCC) theory to study the $5s^2{\;^1}S_0 - 5s5p{\;^3P^o_0}$ clock transition in both Fermionic and Bosonic isotopes of Sr. We compute the excitation energies, E1 and M1 transition amplitudes, hyperfine reduced
matrix elements, and isotope shifts using FSRCC theory. Further, we calculate the lifetime of the metastable clock states for $^{87}$Sr and $^{88}$Sr. Furthermore, we employ perturbed relativistic coupled-cluster (PRCC) theory to compute the ground state electric dipole polarizability of Sr. To improve the accuracy of our results, we incorporate the corrections from the relativistic and
quantum electrodynamical (QED) effects, and perturbative triples to all our calculations. Our computed excitation energies are in good agreement with the experimental data for low-lying excited states. Our results for E1, M1 and HFS reduced
matrix elements are within the experimental error bars, however, with slight difference from the previous calculations due to more accurate treatment of electron correlations in our calculation. Our computed lifetime of the clock state for $^{87}$Sr is within the error bars of the available experimental results, whereas for $^{88}$Sr, it is an order of magnitude smaller than the only available calculation using model potential. Our PRCC result for the ground state polarizability is in good agreement with the experiment, and smaller than previous calculations. As can be expected, our FSRCC results on isotope shift parameters show differences from the MCDF calculations. From the detailed analysis of our results, we find that the corrections from the Breit interaction, QED effects, and perturbative triples are crucial to get accurate clock transition properties in Sr.
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Geophysics · Cross-listed from stat.AP
Residual Kriging for Regional-Scale Canopy Height Mapping: Insights into GEDI-Induced Anisotropies and Sparse Sampling
Kamel Lahssini, Guerric le Maire, Nicolas Baghdadi et al. (+1 more)
Quantifying aboveground biomass (AGB) is essential in the context of global
climate change. Canopy height, which is related to AGB, can be mapped using machine learning models trained with multi-source spatial data and GEDI measurements. In this study, a comparative analysis of canopy height estimates derived from two models is presented: a U-Net deep learning model (CHNET) and a Random Forest
algorithm (RFH). Both models were trained using GEDI
lidar data and utilized multi-source inputs, including optical, radar, and environmental data. While CHNET can leverage its convolutional architecture to account for spatial correlations, we observed that it does not fully incorporate all the spatial autocorrelation present in GEDI canopy height measurements. By conducting a spatial analysis of the models' residuals, we also identified that GEDI data acquisition parameters, particularly the variability in
laser beam energy combined with the azimuthal directions of the observation tracks, introduce spatial inconsistencies in the measurements in the form of periodic patterns. To address these anisotropies, we considered exclusively GEDI power beams, and we conducted our spatial autocorrelation analysis in the GEDI track azimuthal direction. Next, we employed the residual kriging (RK) spatial interpolation technique to account for the spatial autocorrelation of canopy heights and improve the accuracies of CHNET and RFH estimates. Adding RK corrections improved the performance of both CHNET and RFH, with more substantial gains observed for RFH. The corrections appeared to be localized around the GEDI sample points and the density of usable GEDI information is therefore an important factor in the effectiveness of spatial interpolation. Furthermore, our findings reveal that a Random Forest model combined with spatial interpolation can deliver performance comparable to that of a U-Net model alone.
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All authors Kamel Lahssini, Guerric le Maire, Nicolas Baghdadi, Ibrahim Fayad