Atmospheric and Oceanic Physics
A curated UK rain radar data set for training and benchmarking nowcasting models
Viv Atureta, Rifki Priansyah Jasin and Stefan Siegert
This paper documents a data set of UK rain radar image sequences for use in statistical modeling and machine learning methods for nowcasting. The main
dataset contains 1,000 randomly sampled sequences of length 20 steps (15-minute increments) of 2D radar intensity fields of dimension 40x40 (at 5km spatial resolution). Spatially stratified sampling ensures spatial homogeneity despite removal of clear-sky cases by threshold-based truncation. For each radar sequence, additional atmospheric and geographic features are made available, including date, location, mean elevation, mean wind direction and speed and prevailing storm type. New R functions to extract data from the binary "Nimrod" radar data format are provided. A case study is presented to train and evaluate a simple convolutional neural network for radar nowcasting, including self-contained R code.
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Optics · Cross-listed from math.OC
A proof-of-principle experiment on the spontaneous symmetry breaking machine and numerical estimation of its performance on the $K_{2000}$ benchmark problem
Toshiya Sato and Takashi Goh
In a previous paper, we proposed a unique physically implemented type simulator for combinatorial optimization problems, called the spontaneous
symmetry breaking machine (SSBM). In this paper, we first report the results of experimental verification of SSBM using a small-scale
benchmark system, and then describe numerical simulations using the
benchmark problems (K2000) conducted to confirm its usefulness for large-scale problems. From 1000 samples with different initial fluctuations, it became clear that SSBM can explore a single extremely stable state. This is based on the principle of a phenomenon used in SSBM, and could be a notable advantage over other simulators.
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Chemical Physics
Generalization of Long-Range Machine Learning Potentials in Complex Chemical Spaces
Michal Sanocki and Julija Zavadlav
The vastness of chemical space makes generalization a central challenge in the development of machine learning interatomic potentials (MLIPs). While MLIPs could enable large-scale atomistic simulations with near-
quantum accuracy, their usefulness is often limited by poor transferability to out-of-distribution samples. Here, we systematically evaluate different MLIP architectures with long-range corrections across diverse chemical spaces and show that such schemes are essential, not only for improving in-distribution performance but, more importantly, for enabling significant gains in transferability to unseen regions of chemical space. To enable a more rigorous benchmarking, we introduce biased train-test splitting strategies, which explicitly test the model performance in significantly different regions of chemical space. Together, our findings highlight the importance of long-range modeling for achieving generalizable MLIPs and provide a framework for diagnosing systematic failures across chemical space. Although we demonstrate our methodology on metal-organic frameworks, it is broadly applicable to other materials, offering insights into the design of more robust and transferable MLIPs.
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Computational Physics · Cross-listed from cond-mat.stat-mech
Quantum Monte Carlo in Classical Phase Space with the Wigner-Kirkwood Commutation Function. Results for the Saturation Liquid Density of $^4$He
Phil Attard
A Metropolis Monte Carlo
algorithm is given for the case of a complex phase space weight, which applies generally in
quantum statistical mechanics. Computer simulations using Lennard-Jones $^4$He near the $\lambda$-transition, including an expansion to third order of the Wigner-Kirkwood commutation function, give a saturation
liquid density in agreement with measured values.
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Optics
Advantages of Broadband Metalenses for Generalizable Image Classification
Yubo Zhang, Johannes Fröch, Jinlin Xiang et al. (+6 more)
Optical neural networks (ONNs) are gaining increasing
attention to accelerate machine learning tasks. In particular, static meta-optical encoders designed for task-specific pre-processing have demonstrated orders of magnitude smaller energy consumption over purely digital counterparts, albeit at the cost of a slight degradation in classification accuracy. However, a lack of generalizability poses serious challenges for wide deployment of static meta-optical front-ends. Here, we investigate the utility of a single-layer metalens as a meta-optical encoder in ONNs for generalizable image classification. Specifically, we show that a visible-spectrum broadband metalens can achieve image classification accuracy comparable to high-end, sensor-limited optics and consistently outperforms the corresponding hyperboloid baseline across a wide range of sensor pixel sizes and digital backends. We further design an end-to-end optimized single-aperture metasurface for ImageNet classification and observe that the optimization tends to balance the modulation transfer function (MTF) across wavelengths within the sensor-detectable passband. Together, these observations suggest that the preservation of spatial-frequency information is an important factor influencing the performance of ONNs. Our results provide physical insight into the process of task-driven optical optimization and offer practical guidance for the design of high-performance ONNs and meta-optical encoders for generalizable computer
vision tasks.
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All authors Yubo Zhang, Johannes Fröch, Jinlin Xiang, Shane Colburn, Myunghoo Lee, Zhihao Zhou, Minho Choi, Eli Shlizerman, Arka Majumdar
Chemical Physics
Ab initio study of highly charged ion-induced Coulomb explosion imaging
Misa Viveiros, Samuel S. Taylor, Cody Covington et al. (+1 more)
We present a theoretical investigation of ion-induced Coulomb explosion imaging (CEI) of pyridazine molecules driven by energetic C$^{5+}$ projectiles, using time-dependent density-functional theory (TDDFT) with Ehrenfest
nuclear dynamics. By systematically varying the projectile's impact point and orientation relative to the molecular plane, we compare orthogonal and in-plane trajectories and quantify their effects on fragment momenta, electron-density response, and atom-resolved ionization. Newton plots and time-resolved density snapshots show that trajectories avoiding direct atomic collisions yield the most faithful structural reconstructions, whereas direct impacts impart large, highly localized momenta that distort the recovered geometry. Planar trajectories generate substantially greater ionization and broader momentum distributions than orthogonal ones due to deeper traversal through the molecular electron cloud. Quantitative analysis of electron removal at 10~fs confirms that projectile proximity and orientation strongly modulate both local and global ionization. These findings clarify how impact geometry governs the fidelity of ion-induced CEI structural recovery and help explain the variability and noise observed in experimental CEI measurements. More broadly, the results highlight both the strengths and the intrinsic limitations of ion-induced CEI and identify key considerations for interpreting experiments.
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All authors Misa Viveiros, Samuel S. Taylor, Cody Covington, Kálmán Varga
Applied Physics · Cross-listed from cond-mat.mtrl-sci
Moire-Engineered Ferroelectric Transistors for Nearly Trap-free, Low-Power and Non-Volatile 2D Electronics
Arup Singha, Shaili Sett, Kenji Watanabe et al. (+3 more)
Long-range moire patterns in twisted WSe2 enable a built-in, moire-length-scale ferroelectric polarization that can be directly harnessed in electronic devices. Such a built-in ferroic landscape offers a compelling means to enable ultralow-voltage and non-volatile electronic functionality in two-dimensional materials; however, achieving stable polarization control without charge trapping has remained a persistent challenge. Here, we demonstrate a moire-engineered ferroelectric field-effect transistor (FeFET) utilizing twisted WSe2
bilayers that leverages atomically clean van der Waals interfaces to achieve efficient polarization-channel coupling and trap-suppressed, ultralow-voltage operation (subthreshold swing of 64 mV per decade). The device exhibits a stable non-volatile
memory window of 0.10 V and high mobility, exceeding the performance of previously reported two-dimensional FeFET and matching that of advanced silicon-based devices. In addition, capacitance-voltage spectroscopy, corroborated by self-consistent Landau-Ginzburg-Devonshire modeling, indicates ultrafast ferroelectric switching (~0.5 microseconds). These results establish moire-engineered ferroelectricity as a practical and scalable route toward ultraclean, low-power, and non-volatile 2D electronics, bridging atomistic
lattice engineering with functional device architectures for next-generation
memory and logic technologies.
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All authors Arup Singha, Shaili Sett, Kenji Watanabe, Takashi Taniguchi, Arindam Ghosh, Rahul Debnath
Atomic Physics · Cross-listed from cond-mat.mtrl-sci
Predicting interstitial elements in Refractory Complex Concentrated Alloys
Aomin Huang, Siya Zhu, Calvin Belcher et al. (+4 more)
Refractory complex concentrated
alloys, composed of multiple principal refractory elements, are promising candidates for high-temperature structural applications due to their exceptional thermal stability and high melting points. However, their mechanical performance is often compromised by interstitial
impurities, particularly oxygen, nitrogen, and carbon, which segregate to grain boundaries and promote embrittlement. In this study, we investigate the solubility and thermodynamic behavior of oxygen interstitials in a model NbTiHfTa RCCA system. We synthesized NbTiHfTa
alloys with varying oxygen contents via
plasma arc melting and characterized their phase
evolution and microstructure using XRD, SEM, and TEM. Complementary computational modeling was performed using machine-learning interatomic potentials integrated with Monte Carlo simulations to probe oxygen interactions at the atomic scale. Our results reveal a solubility limit for oxygen between 0.8 and 1.0 atomic percentage, beyond which HfO2 formation is energetically favorable. This combined experimental-computational framework provides a predictive approach for managing interstitial behavior in RCCAs, enabling improved
alloy design strategies for enhanced mechanical performance.
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All authors Aomin Huang, Siya Zhu, Calvin Belcher, Ryker Rigsby, Diran Apelian, Raymundo Arróyave, Enrique J. Lavernia
Chemical Physics · Cross-listed from cs.LG
Unveiling Latent Knowledge in Chemistry Language Models through Sparse Autoencoders
Jaron Cohen, Alexander G. Hasson and Sara Tanovic
Since the advent of machine learning, interpretability has remained a persistent challenge, becoming increasingly urgent as generative models support high-stakes applications in drug and material discovery. Recent advances in large
language model (LLM) architectures have yielded chemistry
language models (CLMs) with impressive capabilities in molecular property prediction and molecular generation. However, how these models internally represent chemical knowledge remains poorly understood. In this work, we extend sparse autoencoder techniques to uncover and examine interpretable features within CLMs. Applying our methodology to the Foundation Models for Materials (FM4M) SMI-TED chemistry foundation model, we extract semantically meaningful latent features and analyse their activation patterns across diverse molecular
datasets. Our findings reveal that these models encode a rich landscape of chemical concepts. We identify correlations between specific latent features and distinct domains of chemical knowledge, including structural motifs, physicochemical properties, and pharmacological drug classes. Our approach provides a generalisable framework for uncovering latent knowledge in chemistry-focused AI systems. This work has implications for both foundational understanding and practical deployment; with the potential to accelerate computational chemistry research.
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Biological Physics · Cross-listed from q-bio.QM
Understanding the temperature response of biological systems: Part I – Phenomenological descriptions and microscopic models
Simen Jacobs, Julian Voits, Nikita Frolov et al. (+2 more)
Virtually every biological rate depends on temperature, yet the resulting rate-temperature relationships often deviate strongly from simple Arrhenius behavior. In this first part of a two-part review, we survey phenomenological models used to describe biological temperature responses across scales, from enzymatic reactions to organismal performance. We discuss common functional forms, including symmetric and asymmetric thermal performance curves and extensions of the Arrhenius law, and we highlight how these models define operational quantities such as optimal temperatures, thermal breadths, and thermal limits. We also discuss microscopic models for the effect of temperature, which however do not capture cooperative effects. In Part II of this review, we will discuss how system-level temperature response curves emerge from the interaction of many underlying reactions.
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All authors Simen Jacobs, Julian Voits, Nikita Frolov, Ulrich S. Schwarz, Lendert Gelens
Biological Physics · Cross-listed from cond-mat.stat-mech
Emergent memory in cell-like active systems
Marc Besse and Raphaël Voituriez
Active systems across scales, ranging from molecular machines to human crowds, are usually modeled as assemblies of self-propelled particles driven by internally generated forces. However, these models often assume memoryless dynamics and no coupling of internal active forces to the environment. Here, guided by the example of living
cells, which have recently been shown to display multi-timescale
memory effects, we introduce a general theoretical framework that goes beyond this paradigm by incorporating internal state dynamics and environmental sensing into active particle models. We show that when the self-propulsion of an
agent depends on internal variables with their own complex dynamics - modulated by local environmental cues - environmental
memory spontaneously emerges and gives rise to new classes of behaviours. These include
memory-induced responses, adaptable localization in complex landscapes, suppression of motility-induced phase separation, and enhanced jamming transitions. Our results demonstrate how minimal information processing capabilities, intrinsic to non-
equilibrium agents with internal states like living
cells, can profoundly influence both individual and collective behaviours. This framework bridges
cell-scale activity and large-scale intelligent motion in
cell assemblies, and opens the way to the quantitative analysis and design of systems ranging from synthetic colloids to biological collectives and robotic swarms.
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Atomic Physics · Cross-listed from quant-ph
Observation of a Topological Berry Phase with a Single Phonon in an Ion Microtrap Array
Justin F. Niedermeyer, Nathan K. Lysne, Katherine C. McCormick et al. (+11 more)
Controlled
quantum mechanical motion of trapped atomic ions can be used to simulate and explore collective
quantum phenomena and to process
quantum information. Groups of cold atomic ions in an externally applied trapping potential self-organize into "Coulomb
crystals" due to their mutual electrostatic repulsion. The motion of the ions in these
crystals is strongly coupled, and the eigenmodes of motion all involve multiple ions. While this enables studies of many-body physics, it limits the flexibility and tunability of the system as a
quantum platform. Here, we demonstrate an array of trapped ions in individual trapping sites whose motional modes can be controllably coupled and decoupled by tuning the local applied confining potential for each ion. We show that a single motional
quantum, or
phonon, can be coherently shared among two or three ions confined at the vertices of an equilateral triangle 30 $\mu$m on a side. We can adiabatically tune the ion participation in the motional modes around a closed contour in configuration space, observing that the single-
phonon wavefunction acquires a topological Berry phase if the contour encircles a conical intersection of motional
eigenvalue surfaces. We observe this phase by single-
phonon interference and study its breakdown as the motional mode tuning becomes non-adiabiatic. Our results show that precise, individual
quantum control of ion motion in a two-dimensional array can provide unique access to
quantum multi-body effects.
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All authors Justin F. Niedermeyer, Nathan K. Lysne, Katherine C. McCormick, Jonas Keller, Craig W. Hogle, Matthew G. Blain, Edwin J. Heller, Roman Schmied, Robert Jördens, Susanna L. Todaro, David J. Wineland, Andrew C. Wilson, Daniel H. Slichter, Dietrich Leibfried
Biological Physics
Metabolic rate beyond the 3/4 law
Dorilson Silva Cambui
In earlier work, we introduced a discrete Fibonacci-based ontogenetic model in which the metabolic scaling exponent $b(n)$ is treated as a dynamic function of an organism's developmental stage, and we estimated $b(n)$ for selected mammalian species. In the present article, we revisit this framework with a complementary aim. Rather than proposing new parameter estimates or statistical fits, we provide a didactic, step-by-step reconstruction of the derivation that leads from the recursive growth hypothesis to analytical expressions for the stage-dependent exponent $b(n)$. Building directly on these previously obtained exponents, we then incorporate Kleiber's classical result into the model by interpreting the constant $70$ in the law $B \approx 70\,M^{3/4}$ (with $B$ denoting basal metabolic rate and $M$ body mass) as a metabolic "anchoring point". This yields a stage-dependent basal metabolic rate of the form $B(n) = 70\,M^{b(n)}$, which defines an ontogenetic metabolic trajectory linking recursive growth to changes in scaling. We show, at a conceptual level, how this anchored formulation can describe a shift from strongly sublinear behavior at early stages towards an almost linear regime as development proceeds, while still producing basal rates that are compatible, in order of magnitude, with those reported for mammals of different sizes. In this way, the paper offers a self-contained and pedagogical presentation of the model, emphasizing how ontogenetic changes in metabolic rate can be understood through the combined ideas of Fibonacci-like recursion and metabolic anchoring.
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Plasma Physics
Overview of the Helios Design: A Practical Planar Coil Stellarator Fusion Power Plant
C.P.S. Swanson, S.T.A. Kumar, D.W. Dudt et al. (+39 more)
Thea Energy, Inc. has developed the preconceptual design for "Helios," a fusion power plant based on the planar coil stellarator architecture. In this overview paper, the design is summarized and the reader is referred to the other papers for more detail. The Helios design is based around a two-field-period quasi-axisymmetric ("QA") stellarator
equilibrium with aspect ratio 4.5 and a novel tokamak-like X-point divertor. The natural stability, low recirculating power, and steady-state capability of the stellarator are leveraged. Stability and transport are calculated using state-of-the-art, high-fidelity codes and grounded in measured performance of existing experiments. The electromagnetic coil set is high-temperature superconducting ("HTS") and consists of 12 large,
plasma-encircling coils like the toroidal field coils of a tokamak, and 324 smaller, field-shaping coils. All coils are planar and convex. A maximum of 20 T on-coil is enforced, a value which has been achieved in existing large-bore HTS coils. There is a minimum of 1.2 m between
plasma and coils, leaving space for tritium breeding blanket and
neutron shielding. Because of this thick shielding, all coils have a minimum 40-year operational lifetime, the same minimum lifetime of the power plant system. 1.1 GW of thermal power and 390 MW of net electric power are produced. The shaping coils are individually controllable, enabling a uniquely configurable
magnetic field for relaxed manufacturing and assembly tolerances and
plasma control. A practical maintenance architecture is a primary driver of the design; maintenance is performed on entire toroidal sectors that are removed from between the encircling coils. A biennial maintenance cycle is estimated to take approximately 84 days, resulting in an 88% capacity factor. Rigorous engineering constraints such as temperature and stress limits are enforced.
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All authors C.P.S. Swanson, S.T.A. Kumar, D.W. Dudt, E.R. Flom, W.B. Kalb, T.G. Kruger, M.F. Martin, J.R. Olatunji, S. Pasmann, L.Z. Tang, J. von der Linden, J. Wasserman, M. Avida, A.S. Basurto, M. Dickerson, N. de Boer, M.J. Donovan, A.H. Doudna Cate, D. Fort, W. Harris, U. Khera, A. Koen, J.A. Labbate, N. Maitra, A. Ottaviano, R.K. Parmar, E.J. Paul, B. Reydel, A. van Riel, P.K. Romano, M. Savastianov, S. Saxena, S. Seethalla, S. Srinivasan, R.H. Wu, D. Nash, J. Priebe, M. Slepchenkov, S. Walsh, B. Berzin, D.A. Gates, the Thea Energy team
Classical Physics · Cross-listed from quant-ph
Classical and quantum dynamics of a particle confined in a paraboloidal cavity
Ángel E. Reyna-Cruz and Julio C. Gutiérrez-Vega
We present a classical and
quantum analysis of a particle confined in a three-dimensional paraboloidal cavity formed by two confocal paraboloids. Classically, the system is integrable and presents three independent constants of motion, namely, the energy, the $z$-component of the angular momentum, and a third dynamical constant associated with the paraboloidal geometry, which can be derived from the separability of the Hamilton–Jacobi equation. We derive closed-form analytical expressions for the actions, which allow us to determine the two conditions to get periodic closed trajectories. We classify these trajectories through the indices $(s,t,\ell)$. The caustic paraboloids that bound the motion provide a complete
geometric characterization of admissible trajectories.
Quantum mechanically, separability of the Schrödinger equation in
parabolic coordinates yields eigenmodes described by Whittaker functions. We determine the energy spectrum and identify degeneracies arising not only from azimuthal
symmetry but also from specific cavity deformations. A direct correspondence between classical trajectories and
quantum eigenstates reveals that probability densities concentrate in the classically allowed region with controlled penetration into forbidden zones.
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Medical Physics
Robust External-Beam Calibration of Plastic Scintillation Detectors for In-Vivo Dosimetry in HDR Brachytherapy
Chahrazed Ghannoudi, Marie-Claude Lavallee, Benjamin Cote et al. (+1 more)
Purpose: HDR brachytherapy is a widely adopted modality for cancer treatment. However, it is not free from error and uncertainty. In-vivo dosimetry (IVD) is the only technique that can confirm correct dose delivery. This study details and validates a calibration method for Plastic Scintillation Detector (PSD), bypassing dose gradient and positioning issues in brachytherapy calibration. Methods: The PRB-0057 PSD (Medscint, Canada) was calibrated, 1x1 mm scintillating fiber coupled to a 20 m Eska GH-4001 clear optical fiber (Mitsubishi Rayon, Japan). The fiber is connected to the Hyperscint-RP200 research platform for signal collection. Hyperspectral calibration was performed at a LINAC with a 6 MV beam, enabling removal of stem effects before brachytherapy measurements. For validation, an Iridium-192 Flexisource (Elekta Brachy, The Netherlands), Sk=29447U, was used in a motorized IBA-Blue-Phantom2 water tank (48x48x41cm3). Dose rates were measured at 10 Hz along the source z-axis at a fixed transverse distance of 1.2+/-0.05 cm in 0.2 cm steps. Relative difference (RD) between measured and TG-43U1 dose rates was assessed. A detailed uncertainty budget was associated with brachytherapy measurements. Results: Comparison shows good agreement with RD around 2.5 $\%$ at 1.2 cm, corresponding to positional uncertainties of <0.15 mm. At greater depths up to 8 cm, RDs increase to about 5 $\%$, mainly due to reduced light yield. Uncertainties depend on the source-detector distance, ranging from 3.81 to 6.39 $\%$ (k=1) over the explored range. Conclusions: Results confirm the PSD calibration effectiveness using a 6MV external beam with hyperspectral technique. Uncertainties close to the source align with positional errors and are dominated by reduced PSD sensitivity at larger distances. The study underlined the intrinsic limitation of IVD in the face of known uncertainties.
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All authors Chahrazed Ghannoudi, Marie-Claude Lavallee, Benjamin Cote, Luc Beaulieu
Accelerator Physics
ALS Storage Ring RF Control System Upgrade Plan and Status
Najm Us Saqib, Angel Jurado, Esteban Andrade et al. (+4 more)
The Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory, a third-generation synchrotron light source operational since 1992, is undergoing a comprehensive upgrade of its storage ring RF control system. The legacy Horner PLC controllers and remote I/O modules, now at end-of-life, are being replaced with an Allen-Bradley PLC platform to improve maintainability, reliability, and long-term support. This paper presents the planning, design, and current status of the upgrade project.
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All authors Najm Us Saqib, Angel Jurado, Esteban Andrade, Qiang Du, Jeong Han Lee, Miroslaw Dach, Benjamin Flugstad
Physics and Society
On the accuracy of population level approximation of network processes
Noémi Nagy, Sándor Horváth, Balázs Maga et al. (+1 more)
The individual-based model of simple contagion processes is considered on regular graphs. This model explicitly incorporates the adjacency
matrix of the network enabling us to study the effect of network structure on the dynamic of the propagation process. While the asymptotic behaviour of the model is well known, the transient behaviour has been less studied. Our goal in this paper is to give a theoretical estimate on the accuracy of the one-dimensional population-level approximation. This is carried out for arbitrary simple contagion processes and regular Turán graphs. Numerical evidence is shown that the theoretical estimate is rather sharp for dense graphs.
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All authors Noémi Nagy, Sándor Horváth, Balázs Maga, Péter L. Simon
Optics
Watt-level second harmonic generation in periodically poled thin-film lithium tantalate
Nikolai Kuznetsov, Zihan Li and Tobias J. Kippenberg
Second-harmonic generation (SHG) is a fundamental tool in modern
laser technology, enabling coherent frequency conversion to remote optical bands, serving as the basis for self-referenced femtosecond
lasers and quadrature-squeezed light sources. State-of-the-art SHG relies on bulk
crystals and ridge waveguides, although continuous-wave (CW) SH efficiency in bulk
crystals is limited by short interaction lengths and large mode areas. Ridge waveguides offer better performance with lower pump power requirements, yet must span several centimeters to deliver high output power, complicating fabrication and narrowing the bandwidth. Recently, SHG in periodically poled thin-film lithium niobate integrated photonic
circuits has attracted significant interest, offering orders-of-magnitude improvement in SHG under CW pumping due to the stronger optical mode confinement. However, lithium niobate has a low optical damage threshold, even in MgO-doped substrates, which limits SH power output to well below the watt level. Here, we overcome this challenge and demonstrate 7 mm-long periodically poled thin-film lithium tantalate (PPLT) waveguides that achieve high SH output in the CW regime, with generated power exceeding 1 W and off-chip output above 0.5 W at 775 nm under 4.5 W pump power. PPLT offers a higher optical damage threshold than PPLN and supports watt-level operation. By optimizing electrode geometry and poling conditions, we obtain reproducible poling despite lithium tantalate's coercive field being nearly four times higher than that of MgO-doped lithium niobate. Although its effective nonlinearity is more than five times lower, we achieve watt-level CW output with a short waveguide, demonstrating the potential of PPLT
circuits for high-power applications in integrated
lasers,
quantum photonics, AMO physics, optical clocks, and frequency metrology.
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Optics
Measuring the group velocity dispersion in near resonant hot atomic vapors
Alix Merolle and Quentin Glorieux
Group velocity dispersion (GVD) in near-resonant hot atomic vapors is difficult to measure with standard pulse broadening or interferometric techniques, as absorption, pulse distortion and nonlinearities strongly affect the probe and reduce the signal-to-noise ratio. We introduce a simpler method using a continuous-wave
laser with weak phase modulation and a slow photodetector, directly inspired by Bragg-like spectroscopy in fluids of light. During propagation, the red and blue-detuned sidebands accumulate different dispersive phase shifts, leading to oscillations in the transmitted modulation contrast as the modulation frequency is scanned. Vanishing contrast at well-defined frequencies directly yields the GVD. We apply this technique to hot rubidium vapors and observe the strong frequency dependence of the GVD across a broad detuning range of the D2 line at different temperatures.
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Atomic Physics · Cross-listed from hep-ph
Neutrino Effects on Atomic Measurements of the Weinberg Angle
Mitrajyoti Ghosh, Yuval Grossman, Chinhsan Sieng et al. (+1 more)
We derive a complete expression for the
neutrino-mediated
quantum force beyond the four-
Fermi approximation within the Standard Model. Using this new result, we study the effect of atomic parity violation caused by
neutrinos. We find that the
neutrino effect is sizable compared to the current experimental sensitivity and can also significantly affect the value of the Weinberg angle measured in atomic systems. This offers a promising method for detecting the
neutrino force in the future and facilitates the application of precision atomic physics as a probe for
neutrino physics and the electroweak sector of the Standard Model.
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All authors Mitrajyoti Ghosh, Yuval Grossman, Chinhsan Sieng, Bingrong Yu
Fluid Dynamics · Cross-listed from cond-mat.quant-gas
Vortex leapfrogging and superfluid dissipation mechanisms in a fluid of light
Myrann Baker-Rasooli, Nathan du Toit, Nicolas Pavloff et al. (+1 more)
We report the experimental observation of
vortex leapfrogging in a two-dimensional fluid of light. By imprinting two
vortex-antivortex pairs and tracking their real-time
evolution through phase-resolved imaging, we observe a dynamics that is accurately described by a point-
vortex model with an outward background flow. By precisely controlling the initial
vortex separation, we identify configurations in which leapfrogging breaks down and determine the corresponding dissipation mechanisms. The first originates from phase-slip events occurring at large injected velocities. The second arises when the injection of multi-charged
vortices leads to the formation of a dispersive shock wave which acts as a continuous source of phase slippage. These mechanisms advance our understanding of
vortex dynamics and dissipation in superfluids.
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All authors Myrann Baker-Rasooli, Nathan du Toit, Nicolas Pavloff, Quentin Glorieux
Popular Physics · Cross-listed from astro-ph.IM
Microlensing Signatures of Dyson Sphere-like Structures around Primordial Black Holes as Technosignatures of Extraterrestrial Advanced Civilizations
Shant Baghram
We investigate the microlensing detectability of extraterrestrial technosignatures originating from Dyson sphere \textendash like structures, such as Dyson Swarms surrounding
primordial black holes (PBHs). These hypothetical swarms consist of stochastically varying, partially opaque structures that could modulate standard microlensing light curves through time-dependent transmission effects. We introduce a probabilistic framework that includes a
stochastic transmission model governed by variable optical depth and random gap distributions. We perform a parameter scan and generate heatmaps of the optical transit duration. We study the infrared excess radiation and peak emission wavelength as complementary observational signatures. Additionally, we define and analyze the effective optical depth and the anomalous microlensing event rate for these
stochastic structures. Our findings provide a new avenue for searching for extraterrestrial advanced civilizations by extending microlensing studies to include artificial, dynamic modulation signatures.
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