Optics
The role of modes in nonlinear fiber optical computing
Firdevs Yüce, Bora Çarp{\i}nl{\i}oğlu and Uğur Teğin
We investigate the nonlinear propagation of light in graded-index multimode fiber, utilizing it as an optical computing unit, and quantify how it employs waveguide modes to process information. Using a time-dependent spatiotemporal propagation model with modal decomposition, we evaluate several
benchmark regression and classification tasks and study the modal content of the generated speckles, which couples with a simple digital layer to perform optical computing. Analysis of modal
entropy and energy-based mode counts reveals that effective computation is confined to a low-dimensional modal subspace, whose identity depends on the task and propagation regime. This also sets a trade-off between modal richness and nonlinear beam self-cleaning. These results establish modal statistics as practical design metrics for fiber-based optical computers.
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Biological Physics
Corkscrew motion of Trypanosoma brucei is driven by helical beating of the flagellum and facilitated by its bent shape
Sizhe Cheng, Devadyouti Das, Mykhaylo Barchuk et al. (+4 more)
In the pathogenic parasite Trypanosoma brucei, a laterally attached flagellum drives rapid deformation of the complex
cell body, producing puzzling dynamics. High-speed defocusing imaging reveals that surface points trace flower-like patterns in transverse planes. The petals arise from clockwise flagellar beating, which generates a right-handed helical wave propagating from the anterior tip along the body, advancing the
cell like a twisted corkscrew. The central lobes result from slower counterclockwise body rotation required to balance the active torque. The bent
cell shape underneath the flagellum superimposes these two
chiral motions at different radial distances, producing the observed patterns. Three-dimensional hydrodynamic simulations using the method of regularized Stokeslets reproduce these dynamics and show that bent
cell shape enhances swimming, suggesting an adaptive advantage of T. brucei's morphology.
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All authors Sizhe Cheng, Devadyouti Das, Mykhaylo Barchuk, Raveen Armstrong, Michele M. Klingbeil, Becca Thomases, Shuang Zhou
Accelerator Physics · Cross-listed from hep-ph
Searches for electroweak states at future plasma wakefield colliders
So Chigusa, Simon Knapen, Toby Opferkuch et al. (+3 more)
We quantify the discovery potential of future multi-TeV
plasma wakefield
colliders for new electroweak multiplets. We include beam-beam effects through realistic luminosity spectra, comparing five
collider configurations: $e^+e^-$ and $e^-e^-$ machines with round- and flat-beams, and a $\gamma\gamma$
collider. The beam-beam effects qualitatively change search strategies relative to idealized mono-energetic
lepton colliders, highlighting the importance of the low-energy part of the luminosity spectrum and additional beam-induced initial-state channels. Our results have implications for accelerator R&D priorities, since key electroweak targets may remain accessible even if efficient positron acceleration and flat-beam delivery prove technically challenging at the multi-TeV scale.
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All authors So Chigusa, Simon Knapen, Toby Opferkuch, Inbar Savoray, Christiane Scherb, Weishuang Linda Xu
Fluid Dynamics · Cross-listed from cond-mat.mes-hall
Fluctuation-induced giant magnetoresistance in charge-neutral graphene
A. Levchenko, E. Kirkinis and A. V. Andreev
The Johnson-Nyquist noise associated with the intrinsic conductivity of the electron
liquid, induces fluctuations of the electron density in charge-neutral
graphene devices. In the presence of external electric and
magnetic fields, the fluctuations of charge density and electric current induce a fluctuating hydrodynamic flow. We show that the resulting advection of charge produces a fluctuation contribution to the macroscopic conductivity of the system, $\sigma_{\mathrm{fl}}$, and develop a quantitative theory of $\sigma_{\mathrm{fl}}$. At zero
magnetic field, $\sigma_{\mathrm{fl}}$ diverges logarithmically with the system size and becomes rapidly suppressed at relatively small fields. This results in
giant magnetoresistance of the system.
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Data Analysis and Statistics · Cross-listed from astro-ph.CO
Clues from $\mathcal{Q}$–A null test designed for line intensity mapping cross-correlation studies
Debanjan Sarkar, Ella Iles and Adrian Liu
Estimating the auto power spectrum of cosmological tracers from line-intensity mapping (LIM) data is often limited by instrumental noise, residual foregrounds, and systematics. Cross-power spectra between multiple lines offer a robust alternative, mitigating noise bias and systematics. However, inferring the auto spectrum from cross-correlations relies on two key assumptions: that all tracers are linearly biased with respect to the matter density field, and that they are strongly mutually correlated. In this work, we introduce a new diagnostic statistic, \(\mathcal{Q}\), which serves as a data-driven null test of these assumptions. Constructed from combinations of cross-spectra between four distinct spectral lines, \(\mathcal{Q}\) identifies regimes where cross-spectrum-based auto-spectrum reconstruction is unbiased. We validate its behavior using both analytic toy models and simulations of LIM observables, including
star formation lines ([CII], [NII], [CI],[OIII]) and the 21-cm signal. We explore a range of
redshifts and instrumental configurations, incorporating noise from representative surveys. Our results demonstrate that the criterion \( \mathcal{Q} \approx 1 \) reliably selects the modes where cross-spectrum
estimators are valid, while significant deviations are an indicator that the key assumptions have been violated. The \( \mathcal{Q} \) diagnostic thus provides a simple yet powerful data-driven consistency check for multi-tracer LIM analyses.
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Popular Physics
The Eschatian Hypothesis
David Kipping
The history of astronomical discovery shows that many of the most detectable phenomena, especially detection firsts, are not typical members of their broader class, but rather rare, extreme cases with disproportionately large observational signatures. Motivated by this, we propose the Eschatian Hypothesis: that the first confirmed detection of an extraterrestrial technological civilization is most likely to be an atypical example, one that is unusually "loud" (i.e., producing an anomalously strong technosignature), and plausibly in a transitory, unstable, or even terminal phase. Using a toy model, we derive conditions under which such loud civilizations dominate detections, finding for example that if a society is loud for only $10^{-6}$ of its lifetime, it must emit ${\gtrsim}1$% of its total observable energy budget during that phase to outrun quieter populations. The hypothesis naturally motivates agnostic anomaly searches in wide-field, multi-channel, continuous surveys as a practical strategy for a first detection of extraterrestrial technology.
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Computational Physics · Cross-listed from math.NA
Super-Resolution of Elliptic PDE Solutions Using Least Squares Support Vector Regression
Maryam Babaei, Peter Rucz, Manfred Kaltenbacher et al. (+1 more)
A hybrid computational approach that integrates the finite element method (FEM) with least squares support vector regression (LSSVR) is introduced to solve partial differential equations. The method combines FEM's ability to provide the nodal solutions and LSSVR with higher-order Legendre
polynomial kernels to deliver a closed-form analytical solution for interpolation between the nodes. The hybrid approach implements element-wise enhancement (super-resolution) of a given numerical solution, resulting in high resolution accuracy, while maintaining consistency with FEM nodal values at element boundaries. It can adapt any low-order FEM code to obtain high-order resolution by leveraging localized kernel refinement and parallel computation without additional implementation overhead. Therefore, effective inference/post-processing of the obtained super-resolved solution is possible. Evaluation results show that the hybrid FEM-LSSVR approach can achieve significantly higher accuracy compared to the base FEM solution. Comparable accuracy is a achieved when comparing the hybrid solution with a standalone FEM result with the same
polynomial basis function order. The convergence studies were conducted for four
elliptic boundary value problems to demonstrate the method's ability, accuracy, and reliability. Finally, the
algorithm can be directly used as a plug-and-play method for super-resolving low-order numerical solvers and for super-resolution of expensive/under-resolved experimental data.
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All authors Maryam Babaei, Peter Rucz, Manfred Kaltenbacher, Stefan Schoder
Accelerator Physics · Cross-listed from hep-ph
Photon emission by vortex particles accelerated in a linac
A. Yu. Murtazin, G. K. Sizykh, D. V. Grosman et al. (+3 more)
We study the
photon emission by charged spinless particles with phase
vortices and an orbital angular momentum (OAM) projection in longitudinal electric and
magnetic fields within the scalar QED. A realistic wave packet of an electron or ion accelerated by a
radio-frequency wave locally feels a constant and spatially homogeneous field, which allows us to develop an effective model for losing the angular momentum of the
vortex particle due to
photon emission. For the fields typical for accelerator facilities, we find that an effective lifetime of the
vortex state greatly exceeds the acceleration time. This proves that the acceleration of
vortex electrons, ions,
muons, and so forth to relativistic energies is possible in conventional linacs, as well as in the wake-field accelerators with higher field gradients, the OAM losses due to the
photon emission are mostly negligible, and that the
vortex quantum state is highly robust against these losses.
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All authors A. Yu. Murtazin, G. K. Sizykh, D. V. Grosman, U. G. Rybak, A. A. Shchepkin, D. V. Karlovets
Optics
Optical arbitrary waveform generation using spectro-temporal unitary transforms
Callum Deakin
We discuss the prospect of using cascaded phase modulators and dispersive elements to achieve arbitrary optical waveform generation. This transform is not limited by the bandwidth of its constituent modulators and is theoretically lossless.
Accelerator Physics
Evaluating Function-as-a-Service (FaaS) frameworks for the Accelerator Control System
A. Jaikar, J. Diamond, A. Tiradani et al. (+1 more)
As particle accelerator control systems evolve in complexity and scale, the need for responsive, scalable, and cost-effective computational infrastructure becomes increasingly critical. Function-as-a-Service (FaaS) offers an alternative to traditional monolithic architecture by enabling event-driven execution, automatic scaling, and fine-grained resource utilization. This paper explores the applicability and performance of FaaS frameworks in the context of a modern particle accelerator control system, with the objective of evaluating their suitability for short lived and triggered workloads. In this paper, we evaluate prominent open-source FaaS platforms in executing functional logic, triggers, and diagnostics routines. Evaluation metrics consist of cold-start latency, scalability, performance, integration with other open-source tools like Kafka. Experimental workloads were designed to simulate real-world control tasks when implemented as stateless FaaS functions. These workloads were benchmarked under various invocation loads and network conditions. Self-hosted FaaS platforms, when deployed within accelerator networks, offer greater control over execution environment, better integration with legacy systems, and support for real-time guarantees when paired with message queues. Based on lessons learned and evaluation metrics, this paper describes reliability of the FaaS framework for the Accelerator Control Systems (ACS).
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All authors A. Jaikar, J. Diamond, A. Tiradani, B. Harrison
Fluid Dynamics
Buoyancy-dependent induced flow by vertically migrating swimmers
Nina Mohebbi and John O. Dabiri
Collective vertical swimming may generate aggregate-scale flows that contribute to mixing and transport in stratified environments. The strength of these flows depends not only on swimmer behavior but also on environmental properties. Here we examine how fluid density affects flow generated by vertically migrating swarms of brine shrimp $\textit{Artemia salina}$. Using simultaneous three-dimensional swimmer tracking and particle image velocimetry, we measured swimmer kinematics and the induced flow field during phototactically driven migrations under four controlled salinity conditions. Induced velocity increased with buoyancy forcing and scaled with the parameter $N(\rho_s - \rho)$, where $N$ is the number of swimmers and $\rho_s - \rho$ is the density difference between swimmers and the surrounding fluid ($R^2 = 0.70$, $p = 5.9 \times 10^{-5}$). A multiple regression including swimmer number, swimming speed, fluid density, and the swarm Gaussian width confirmed that density remained a significant predictor of induced velocity after controlling for the other variables ($p = 0.012$, $R^2 = 0.82$). A simplified actuator-disk model captures the first-order dependence of induced velocity on buoyancy forcing and swimmer momentum, suggesting that environmentally driven density variations can substantially modify the hydrodynamic impact of collective vertical migration.
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Atmospheric and Oceanic Physics
A Model Intercomparison Study of Mixed-Phase Clouds in a Laboratory Chamber
Aaron Wang, Sisi Chen, Steve Krueger et al. (+12 more)
Mixed-phase clouds, composed of supercooled
liquid droplets and ice
crystals, play a critical role in weather and
climate systems. Their complex microphysical interactions and coupling with
turbulence at microscales govern the cloud properties at macroscales, yet remain challenging to observe and quantify under atmospheric conditions. This model intercomparison study utilizes ten model configurations to simulate mixed-phase cloud
evolution in the Michigan Technological University's Pi Chamber. The models span a range of frameworks, including box models, direct numerical simulation, and large-eddy simulation models, and incorporate both bin and Lagrangian microphysics. Each model was tuned to reproduce the observed
liquid-phase steady state prior to ice injection. Ice particles were then introduced into the domain at various rates to examine cloud glaciation behavior. By the intercomparison design, all models successfully reproduced the observed mean droplet radius and number concentration during the
liquid-phase stage. Increasing ice particle injection rates led to consistent qualitative trends across models: depletion of
liquid water, reduced total water content, and a shift in particle size distributions toward larger radii. However, quantitative differences arose due to variations in model treatment in dynamics and microphysics, including subgrid-scale
turbulence parameterizations, wall forcing, and particle removal parameterizations. Most models that simulate the full chamber retained
liquid droplets near the lower boundary, where supersaturation forcing is strongest and droplets are replenished before mixing into the core region. These surviving
liquids droplets were absent in simulations assuming a well-mixed domain, excluding the near-wall region, or using coarse grid spacing.
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All authors Aaron Wang, Sisi Chen, Steve Krueger, Piotr Dziekan, Kotaro Enokido, Fabian Hoffmann, Agnieszka Makulska, Bernhard Mehlig, Gaetano Sardina, Grigory Sarnitsky, Silvio Schmalfuß, Shin-ichiro Shima, Fan Yang, Mikhail Ovchinnikov, Raymond A. Shaw
Computational Physics · Cross-listed from cs.RO
Py-DiSMech: A Scalable and Efficient Framework for Discrete Differential Geometry-Based Modeling and Control of Soft Robots
Radha Lahoti, Ryan Chaiyakul and M. Khalid Jawed
High-fidelity simulation has become essential to the design and control of soft
robots, where large
geometric deformations and complex contact interactions challenge conventional modeling tools. Recent advances in the field demand simulation frameworks that combine physical accuracy, computational scalability, and seamless integration with modern control and optimization pipelines. In this work, we present Py-DiSMech, a Python-based, open-source simulation framework for modeling and control of soft robotic structures grounded in the principles of Discrete Differential Geometry (DDG). By discretizing
geometric quantities such as
curvature and strain directly on meshes, Py-DiSMech captures the nonlinear deformation of rods, shells, and hybrid structures with high fidelity and reduced computational cost. The framework introduces (i) a fully vectorized NumPy implementation achieving order-of-magnitude speed-ups over existing geometry-based simulators; (ii) a penalty-energy-based fully implicit contact model that supports rod-rod, rod-shell, and shell-shell interactions; (iii) a natural-strain-based feedback-control module featuring a proportional-integral (PI) controller for shape regulation and trajectory tracking; and (iv) a modular, object-oriented software design enabling user-defined elastic energies, actuation schemes, and integration with machine-learning libraries.
Benchmark comparisons demonstrate that Py-DiSMech substantially outperforms the state-of-the-art simulator Elastica in computational efficiency while maintaining physical accuracy. Together, these features establish Py-DiSMech as a scalable, extensible platform for simulation-driven design, control validation, and sim-to-real research in soft robotics.
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Fluid Dynamics
A GPU-Accelerated Fully Coupled Fluid-Solid-Thermal SPH Solver for Industrial Gearboxes: Application to Lubricant Flow and Heat Transfer in a Bevel-Helical Reducer
Yongchuan Yu, Dong Wu, Oskar J. Haidn et al. (+1 more)
This study presents a GPU-accelerated, fully coupled fluid-solid-thermal Smoothed Particle Hydrodynamics (SPH) framework for high-fidelity analysis of splash-lubricated gearboxes. A series of thermo-fluid simulations of a bevel-helical gear reducer were conducted by varying shaft speed, oil immersion depth, and lubricant viscosity to evaluate their influence on splash dynamics, churning losses, and lubricant temperature rise. The results show that churning losses increase by nearly an order of magnitude as the speed rises from 150 to 600 rad/s, while the corresponding lubricant temperature rise becomes approximately three to four times smaller. Variations in immersion depth and viscosity adjust the heating rate only modestly-typically within 10-20%-with their influence reversing between low- and high-speed regimes. The GPU backend provides a 7-9 speedup over a high-performance desktop CPU, enabling multi-million-particle, full-gearbox thermo-fluid simulations without specialized hardware. These findings demonstrate the feasibility of high-fidelity thermal analysis of industrial gearboxes and provide quantitative insight into the coupled splash, churning, and heat-transfer mechanisms that govern gearbox thermal performance.
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All authors Yongchuan Yu, Dong Wu, Oskar J. Haidn, Xiangyu Hu
Optics · Cross-listed from cond-mat.quant-gas
Atom and spin resolved imaging in a single shot
Tobias Hammel, Maximilian Kaiser, Daniel Dux et al. (+2 more)
We report on an imaging scheme for
quantum gases that enables simultaneous detection of two
spin states with single-atom resolution. It utilizes the polarization of the emitted
photons during fluorescence by choosing appropriate internal states of lithium-6 atoms in a
magnetic field. This scheme can readily be implemented to obtain in-situ
spin correlations in a wide variety of experimental settings.
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All authors Tobias Hammel, Maximilian Kaiser, Daniel Dux, Matthias Weidemüller, Selim Jochim
Classical Physics · Cross-listed from math-ph
Effective Operators in the Theory of Composites: Hilbert Space Framework
Aaron Welters
In this chapter, the
Hilbert space framework in the mathematical theory of composite materials is introduced for studying the properties of effective operators. The goal is to introduce some of the key concepts and fundamental
theorems in this area while showing that they follow naturally from using only basic results in operator theory on
Hilbert spaces. These concepts include the $Z$-problem as an abstraction of a constitutive equation defined in terms of a bounded linear operator on a
Hilbert space with a Hodge decomposition, direct and dual $Z$-problems with the duality interpretation of the inverse of an effective operator, and the notion of an $n$-phase composite with orthogonal $Z(n)$-subspace collection. These
theorems include sufficient conditions for the existence and uniqueness of both the solution of a $Z$-problem and the effective operator of a $Z$-problem, a representation formula for the effective operator as an operator Schur complement, the Dirichlet and Thomson minimization principles for the effective operator, the result on monotonicity and concavity of the effective operator map, and the Keller-Dykhne-Mendelson duality relations. Moreover, another important
theorem given here (which may also be of independent interest to systems theorists) says that an effective operator of an $n$-phase composite with orthogonal $Z(n)$-subspace collection is the Schur complement of a normalized homogeneous semidefinite operator pencil (in particular, has a Bessmertnyĭ realization) and, up to a
unitary equivalence, the converse is also true. Finally, the general theory presented here is shown to recover classical results dealing with effective conductivity but can also be applied to many other important problems involving composites in physics and engineering, e.g., in elasticity and electromagnetism.
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Optics · Cross-listed from quant-ph
Practical and Efficient Verification of Entanglement with Incomplete Measurement Settings
Jiheon Seong, Jin-Woo Kim, Seungchan Seo et al. (+6 more)
In this work, we present a practical and efficient framework for verifying entangled states when only a tomographically incomplete measurement setting is available-specifically, when access to observables is severely limited. We show how the experimental estimation of a small number of observables can be directly exploited to construct a large family of
entanglement witnesses, enabling the efficient identification of entangled states. Moreover, we introduce an optimization approach, formulated as a semidefinite program, that systematically searches for those witnesses best suited to reveal
entanglement under the given measurement constraints. We demonstrate the practicality of the approach in a proof-of-principle experiment with
photon-polarization
qubits, where
entanglement is certified using only a fraction of the full measurement data. These results reveal the maximal usefulness of incomplete measurement settings for
entanglement verification in realistic scenarios.
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All authors Jiheon Seong, Jin-Woo Kim, Seungchan Seo, Seung-Hyun Nam, Anindita Bera, Dariusz Chruściński, June-Koo Kevin Rhee, Heonoh Kim, Joonwoo Bae
Optics
Noise dynamics in large mode volume Brillouin lasers
Andrew J. Shepherd, Daniel J. Blumenthal and Ryan O. Behunin
Photonic integrated Brillouin
lasers have emerged as an important tool to realize a wide range of precision applications, including atomic time-keeping, low-noise microwave signal generation, fiber and
quantum sensing, and ultra-high capacity coherent communications. While Brillouin
lasers routinely achieve sub-Hz instantaneous linewidths, many of these applications also require exceptional frequency stability and high-power single-mode emission. A recent demonstration showed that extending the resonator length increases the
laser power while also improving the frequency stability through suppression of thermorefractive noise. However, as the resonator scales to larger lengths, multiple optical resonances can be found within the Brillouin gain bandwidth, greatly complicating the
laser dynamics compared to existing coupled-mode Brillouin
laser models. Given the potential to scale
lasers of this type to watt-level output powers at sub-mHz linewidths, a theoretical model describing this physics is needed to provide key insights into their performance. Here, we develop a coupled-mode theory of integrated large mode volume Brillouin
lasers, accounting for multiple cavity modes with potential to lase within the gain bandwidth. We obtain expressions for the steady-state dynamics, spontaneous spectrum, relative intensity noise, and frequency noise. Our analysis reveals that the broad gain bandwidth results in atypical Brillouin dynamics, giving rise to distinct features in the noise spectra, and consequently modifications of the standard, single-mode fundamental linewidth of Brillouin
lasers. Additionally, these features may be used for a variety of tangential applications, such as
phonon spectroscopy or quality factor enhancement. Furthermore, we find that the linewidth can be significantly impacted by transferred RIN from the external pump in Brillouin
lasers that lack ideal phase matching.
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Atomic Physics · Cross-listed from cond-mat.quant-gas
Programmable Assembly of Ground State Fermionic Tweezer Arrays
Naman Jain, Jin Zhang, Marcus Culemann et al. (+1 more)
We demonstrate deterministic preparation of arbitrary two-component product states of fermionic $^6$Li atoms in an 8$\times$8 optical tweezer array, achieving motional ground-state fidelities above $98.5\,\%$. Leveraging the large differential
magnetic moments for
spin-resolution, with parallelized site- and number-resolved control, our approach addresses key challenges for low-
entropy quantum state engineering. Combined with high-fidelity
spin-, site-, and density-resolved readout within a single $20\,\mathrm{\mu s}$ exposure, and $3\,\mathrm{s}$ experimental cycles, these advances establish a fast, scalable, and programmable architecture for fermionic
quantum simulation.
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All authors Naman Jain, Jin Zhang, Marcus Culemann, Philipp M. Preiss
Geophysics · Cross-listed from astro-ph.EP
The Oxygen Valve on Hydrogen Escape Since the Great Oxidation Event
Gregory J. Cooke, Dan R. Marsh, Catherine Walsh et al. (+2 more)
The Great Oxidation Event (GOE) was a $200$ Myr transition circa 2.4 billion years ago that converted the Earth's anoxic atmosphere to one where molecular oxygen (O$_2$) was abundant (volume mixing ratio $>10^{-4}$). This significant rise in O$_2$ is thought to have substantially throttled hydrogen (H) escape and the associated water (H$_2$O) loss. Atmospheric estimations from the GOE onward place O$_2$ concentrations ranging between 0.1% to 150% PAL, where PAL is the present atmospheric level of 21% by volume. In this study we use WACCM6, a three-dimensional Earth System Model to simulate Earth's atmosphere and predict the
diffusion-limited escape rate of hydrogen due to varying O$_2$ post-GOE. We find that O$_2$ indirectly acts as a control valve on the amount of hydrogen atoms reaching the homopause in the simulations: less O$_2$ leads to decreased O$_3$ densities that reduce local tropical tropopause temperatures by up to 17 K, which increases H$_2$O freeze-drying and thus reduces the primary source of hydrogen in the considered scenarios. The maximum differences between all simulations in the total H mixing ratio at the homopause and the associated
diffusion-limited escape rates are a factor of 3.2 and 4.7, respectively. The prescribed CH$_4$ mixing ratio (0.8 ppmv) sets a minimum
diffusion escape rate of $\approx 2 \times 10^{10}$ mol H yr$^{-1}$, effectively a negligible rate when compared to pre-GOE estimates ($\sim10^{12}-10^{13}$ mol H yr$^{-1}$). Because the changes in our predicted escape rates are comparatively minor, our numerical predictions support geological evidence that the majority of Earth's hydrogen escape occurred prior to the GOE. Our work demonstrates that estimations of how the hydrogen escape rate evolved through Earth's history requires 3D chemistry-
climate models which include a global treatment of water vapour microphysics.
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All authors Gregory J. Cooke, Dan R. Marsh, Catherine Walsh, Felix Sainsbury-Martinez, Marrick Braam
Physics Education
Perspectives of Women and Men Students and Faculty on Conceptual and Quantitative Problem-Solving in Physics from Introductory to Graduate Levels
Apekshya Ghimire and Chandralekha Singh
Developing expertise in physics requires appropriate integration and assimilation of physics and mathematics. Instructors and students often describe physics courses in terms of their emphasis on conceptual and quantitative problem-solving. For example, they may argue that a course emphasizes primarily conceptual over quantitative problem-solving or may emphasize equally on both depending on instructional context and assessment design. In this study, we investigated how students and instructors across different levels of physics instruction perceive the roles and development of conceptual and quantitative problem-solving in student learning and expertise development. Using departmental surveys administered at the beginning and end of each semester, we collected both Likert-scale and open-ended responses from students enrolled in introductory, upper-level undergraduate and graduate physics courses. These surveys assessed students' self-perceived skills, preferences and perceptions of instrucots and course emphasis. To complement student perspectives, we conducted interviews with instructors using parallel questions adapted to reflect instructional goals and expectations. Our findings highlight patterns in how students and instructos prioritize conceptual and quantitative problem-solving across course levels, as well as
alignment and misalignment between student and instructor perspectives.
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Applied Physics
Comparison of time-resolved photoluminescence and deep-level transient spectroscopy defect evaluations in an InAs nBn detector subjected to in-situ and ex-situ 63 MeV proton irradiation
Rigo A. Carrasco, Christopher P. Hains, Nathan Gajowski et al. (+9 more)
Deep-level transient spectroscopy and temperature-dependent time-resolved photoluminescence experiments are performed on identical InAs nBn photodetector structures as a function of in-situ and ex-situ 63 MeV
proton irradiation to assess their generation and recombination dynamics. Pre-irradiation, the n-type InAs absorbing region exhibits a steadily increasing minority carrier lifetime with increasing temperature, providing evidence that excited minority carriers may be recombining via shallow defect levels. From deep-level transient spectroscopy, two features are found between 10 K and 275 K: a low temperature broad shoulder, which suggests emission from multiple shallow electron defect levels with energies < 29 meV, and a high temperature minimum occurring at approximately 230 K with an activation energy of 539 meV, which suggests a defect in the barrier layer in the device. Two similar nBn detectors are then subjected to 63 MeV
proton irradiation in step doses and measured between steps. One experiment is performed in-situ with an nBn held at approximately 10 K during dosing, and the other experiment is performed ex-situ with a similar nBn held at room temperature for dosing. The ex-situ dosing results in an evaluation of the defect introduction rate that is three to four times lower than in-situ due to partial annealing of the
proton-induced displacement damage at room temperature. The results for these two experiments are then compared with the dose-dependent recombination rate analysis, resulting in an estimated recombination defect cross-section of 1.6x10^(-13) cm^2 for the shallow shoulder defect.
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All authors Rigo A. Carrasco, Christopher P. Hains, Nathan Gajowski, Alexander T. Newell, Julie V. Logan, Zinah M. Alsaad, Preston T. Webster, Christian P. Morath, Diana Maestas, Aaron J. Muhowski, Samuel D. Hawkins, Evan M. Anderson
Plasma Physics
Damped Kinetic Alfvén Waves in Earth's Magnetosheath: Numerical Simulations and MMS Observations
Mani K. Chettri, Hemam D. Singh, Vivek Shrivastav et al. (+2 more)
The Earth's magnetosheath provides a high $\beta$ (ratio of electron thermal pressure to
magnetic pressure)
plasma environment where kinetic Alfvén waves (KAWs) strongly influence
turbulence and energy dissipation. This study investigates how Landau damping modifies the nonlinear
evolution of KAWs by solving a modified nonlinear Schrödinger equation that captures both dispersive and nonlinear effects. Without Landau damping, modulational instability drives rapid self-focusing into intense
magnetic filaments, producing a turbulent cascade with $k_\perp^{-5/3}$ scaling in the inertial range ($k_\perp\rho_i<1$) that transitions to $k_\perp^{-8/3}$ at sub-ion scales ($k_\perp\rho_i>1$), here $k_\perp$ is the wavevector component perpendicular to the background
magnetic field and $\rho_i$ the ion thermal gyroradius. When Landau damping is included,
magnetic structures are significantly suppressed, and the spectrum steepens to $k_\perp^{-11/3}$ in the sub-ion range while the inertial range maintains $k_\perp^{-5/3}$ scaling. The damping acts across all scales through resonant wave-particle interactions, efficiently transferring energy from waves to particles. Direct comparison with Magnetospheric Multiscale (MMS) spacecraft observations shows that the observed kinetic range spectral slope falls between our undamped and damped simulation limits, consistent with an intermediate damping regime in magnetosheath
turbulence. This agreement confirms that Landau damping is one of the primary mechanisms controlling turbulent energy dissipation at kinetic scales in collisionless
plasmas.
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All authors Mani K. Chettri, Hemam D. Singh, Vivek Shrivastav, Britan Singh, Rupak Mukherjee
Instrumentation and Detectors
Scintillation response of cryogenic CsI to few-keV and sub-keV nuclear recoils
J.I. Collar, C.M. Lewis, A. Simón et al. (+1 more)
Monochromatic
neutron emissions from photonuclear sources $^{88}$Y/Be and $^{124}$Sb/Be are employed to obtain the response of pure (undoped) cesium iodide at 80 K. The use of a low-noise, high-
quantum-efficiency avalanche photodiode in combination with a novel waveshifter results in a 70 eV analysis threshold. This reach allows to observe signals from sub-keV
nuclear recoils originating in
neutron scattering. The extracted quenching factor drops much faster towards low energy than the extrapolation of a model developed for room-temperature CsI[Na]. We comment on the impact of our measurement on planned use of cryogenic CsI in
neutrino physics and dark matter experiments.
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All authors J.I. Collar, C.M. Lewis, A. Simón, S.G. Yoon
Applied Physics · Cross-listed from cond-mat.mtrl-sci
Linear and Nonlinear Optical Properties of SiO$_2$/TiO$_2$ Heterostructures Grown by Plasma Enhanced Atomic Layer Deposition
Jinsong Liu, Martin Mičulka, Raihan Rafi et al. (+7 more)
Second harmonic (SH) radiation can only be generated in non-centrosymmetric bulk
crystals under the electric-dipole approximation. Nonlinear thin films made from bulk
crystals are technologically challenging because of complex and high temperature fabrication processes. In this work,
heterostructures made of amorphous materials SiO$_2$ and TiO$_2$ were prepared by a CMOS-compatible technique named
plasma enhanced atomic layer deposition (PEALD) with deposition temperature at 100 {\deg}C. By using the uniaxial dispersion model, we characterized the form-birefringence properties, which can enable the phase matching condition in waveguides or other nonlinear optical applications. By applying a fringe-based technique, we determined the largest diagonal component of the effective second-order bulk susceptibility $\chi_{zzz}^{(2)}$ = 1.30$\pm$0.13 pm/V at a wavelength of 1032 nm. Noteworthy, we observed strong SH signals from two-component nanolaminates, which are several orders of magnitude larger than from single layers. The SH signals from our samples only require the broken inversion
symmetry at the interface. Here optical properties of nanocomposites can be precisely tuned by the promising PEALD technology.
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All authors Jinsong Liu, Martin Mičulka, Raihan Rafi, Sebastian Beer, Denys Sevriukov, Stefan Nolte, Sven Schröder, Andreas Tünnermann, Isabelle Staude, Adriana Szeghalmi
Plasma Physics
Density of hybrid plasma generated by microwave and laser radiation in the Ar:H2:CH4 mixture
S.V. Avtaeva, V.B. Dolomanova, P.A. Pinaev et al. (+1 more)
The atmospheric-pressure hybrid
plasma in the Ar:H2:CH4 mixture, maintained by microwave radiation (2.47 GHz) and CO2
laser radiation (10.6 {\mu}m) in the chamber of an experimental
plasma-chemical reactor designed to study the synthesis of diamond-like coatings was studied. The electron number density was determined from the Stark broadening of the H{\alpha} line shape of atomic hydrogen. It was shown that when
laser radiation is focused in the region of a microwave
plasma bunch, the H{\alpha} line shape in the hybrid
plasma spectra has broad wings and is described by a Lorentz function with a two-contour approximation. The complex structure of the H{\alpha} line profile of the hybrid
plasma indicates its spatiotemporal inhomogeneity. The electron number density corresponding to the contour with a smaller half-width exceeds the electron number density in microwave
plasma and lies in the range of (4-8)E15 cm-3, and the electron number density measured by the contour with a larger half-width is (1.5-2)E17 cm-3.
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All authors S.V. Avtaeva, V.B. Dolomanova, P.A. Pinaev, A.E. Medvedev
Fluid Dynamics · Cross-listed from cond-mat.stat-mech
Burgers dynamics for Poisson point process initial conditions of the Weibull class
Patrick Valageas
We derive the statistical properties of one-dimensional Burgers dynamics with
stochastic initial conditions for the velocity potential defined by a Poisson point process whose intensity follows a power law with exponent $\alpha > -1$. Working in the inviscid limit and exploiting the geometrical construction of solutions in terms of first-contact parabolas, we derive explicit analytical expressions for a broad set of statistical quantities. These include the one- and two-point probability distributions of the velocity, the multiplicity functions of voids and shocks, and the velocity and density correlation functions together with their associated power spectra. We also show that the full hierarchy of $n$-point distributions factorizes into a sequence of two-point conditional probabilities. This class of initial conditions leads to self-similar
evolution and produces probability distributions characterized by stretched-exponential tails, with tail exponents spanning the full range from unity to infinity. The associated characteristic length scale grows as a power law of time, with an exponent lying between zero and one half.
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Chemical Physics
Frequency-Dependent Polarization Propagator Calculation for Quantum Dots Using Optimized Inverse Krylov Subspace and Folded-Spectrum Method
Chandler Martin, Nicole Spanedda, Anaira Jalan et al. (+3 more)
Accurate prediction of the frequency response of
quantum dots under electromagnetic radiation is essential for investigating absorption spectra, excitonic effects, and nonlinear optical behavior in
quantum dots and
semiconductor nanoparticles. The polarization propagator provides a rigorous framework for evaluating these properties, but its construction is computationally demanding. Challenges arise from the level of electron correlation, the size of the excitonic basis, and the cost of evaluating two-electron integrals. This work addresses these difficulties by developing first- and second-order frequency-dependent polarization propagator calculations for PbS and CdS
quantum dots. The propagator is formulated using the electron propagator approach and expressed as the resolvent of the
Hamiltonian superoperator. Light-matter interaction is treated using the dipole approximation and represented in a particle-hole excitation operator basis. The correlated ground state is treated at the MP2 level, and all response-
matrix terms up to second order in the fluctuating potential are included. A frequency-dependent inverse Krylov subspace method is derived and combined with the folded-spectrum technique to isolate excitation energies within a chosen frequency window. This strategy avoids full diagonalization of the response
matrix and significantly reduces computational cost for large systems. The method is implemented in a
matrix-free manner in which no explicit response
matrix is assembled, and all operations rely on
matrix-vector products. UV-VIS excitation spectra of PbS and CdS
quantum dots were computed, demonstrating that the inverse Krylov subspace projection approach provides an efficient and accurate approximation for excitation spectra when full diagonalization is computationally prohibitive.
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All authors Chandler Martin, Nicole Spanedda, Anaira Jalan, Emily Schafer, Jessica Beyer, Arindam Chakraborty
Chemical Physics
Time-dependent ab__initio molecular-orbital decomposition for high-harmonic generation spectroscopy
Marco Marchetta, Chiara Morassut, Julien Toulouse et al. (+2 more)
We propose a real-time time-dependent ab__initio approach within a configuration-interaction-singles ansatz to decompose the high-harmonic generation (HHG) signal of molecules in terms of individual molecular-orbital (MO) contributions. Calculations have been performed by propagating the time-dependent Schrödinger equation with complex energies, in order to account for ionization of the system, and by using tailored Gaussian basis sets for high-energy and continuum states. We have studied the strong-field electron dynamics and the HHG spectra in aligned CO2 and H2O molecules. Contribution from MOs in the strong-field dynamics depends on the interplay between the MO ionization energy and the coupling between the MO and the
laser-pulse
symmetries. Such contributions characterize different portions of the HHG spectrum, indicating that the orbital decomposition encodes nontrivial information on the modulation of the strong-field dynamics. Our results correctly reproduce the MO contributions to HHG for CO2 as described in the literature experimental and theoretical data and lead to an original analysis of the role of the highest occupied molecular orbitals HOMO, HOMO-1, and HOMO-2 of H2O according to the polarization direction of the
laser pulse.
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All authors Marco Marchetta, Chiara Morassut, Julien Toulouse, Emanuele Coccia, Eleonora Luppi
Physics Education
Lessons from pendulums: A design comparison of three lab activities
Ian Descamps, Roger Tobin, Paul Wagoner et al. (+3 more)
We present three versions of a pendulum lab activity to explore how theoretical commitments, motivations, and aspirations reflect in curriculum design. In earlier work, Boudreaux & Elby (2020) discussed how different theoretical perspectives led them to different designs of tutorials. Here, we discuss our finding that even starting from the same theoretical perspective and having similar goals for students can lead to differences of design. We give three interacting reasons why our labs diverge: We have different expectations of students at our respective institutions; we have different ancillary goals; and we draw different implications from our shared theoretical commitments. Our account demonstrates the complexity of the relationship between theory, goals, and curriculum design. In this way, it adds to prior arguments for the importance of designers' articulating the
reasoning for their choices as well as for the possible value of instructors' responsive adaptations to curricula.
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All authors Ian Descamps, Roger Tobin, Paul Wagoner, David Hammer, N. G. Holmes, Rachel E. Scherr