Papers

Computational plasma physics increasingly relies on high-performance computing (HPC) methods, including particle-in-cell (PIC), gyrokinetic, and magnetohydrodynamic (MHD) simulations, yet field-wide evidence on how method choice, team size, and GPU adoption shape research outputs remains limited. We analyze 5,522 computational plasma physics papers published on arXiv between 2010 and 2025 using large-scale text mining, employing abstract length as a proxy for methodological and algorithmic complexity. Using ordinary least squares (OLS), tobit, and logistic regression models, we examine how abstract length and GPU mentions vary with computational method, number of authors, and publication year. Controlling for collaboration size and temporal trends, results show that MHD studies have longer abstracts than PIC and gyrokinetic papers, indicating more extensive methodological and physical exposition. Abstract length increases modestly with team size, while temporal effects suggest gradual changes in abstract conciseness over time. At the same time, PIC and gyrokinetic methods have grown substantially in relative prevalence over the past decade and are strongly linked to GPU adoption, reflecting their higher computational intensity and suitability for accelerator-based architectures. Together, these findings highlight a decoupling between methodological verbosity and method prevalence, offering a new bibliometric perspective on the evolution of HPC-driven plasma physics research.

We investigate the linear stability of particle-laden pulsatile channel flow using Floquet analysis within a two-phase dusty-gas framework. Uniformly distributed spherical particles are coupled to an incompressible Newtonian fluid through Stokes drag, and the governing equations are linearized about a time-periodic base flow driven by a sinusoidally varying pressure gradient. The effects of Reynolds number, Womersley number, pulsation amplitude, particle relaxation time, and particle mass fraction on temporal instability are examined. In the steady limit, particles with very short relaxation times destabilize the flow, whereas finite relaxation times introduce interphase slip and drag-mediated damping that stabilize disturbances. Under pulsatile forcing, increasing pulsation amplitude destabilizes the flow at low Womersley numbers but stabilizes it at sufficiently high Womersley numbers. This transition is governed by the penetration depth of oscillatory motion and is systematically shifted by particle relaxation time and mass loading through interphase momentum exchange. A critical corresponding value remains small throughout, indicating strong particle-fluid coupling and ruling out resonance-like particle dynamics. These findings provide a unified physical framework for the stability of pulsatile particle-laden flows relevant to physiological and periodically forced multiphase systems.

Effects of wind direction in realistic urban canopies remain difficult to characterize systematically because local flow patterns, building-height variability, and turbulent statistics within a realistic urban canopy may respond differently to changes in the approaching wind. To investigate these multi-scale directional impacts, we conducted high-resolution large-eddy simulations of the atmospheric boundary layer over the Zona Universitaria Pedralbes district in Barcelona. The computational meshes employ fourth-order spectral elements, yielding pedestrian-level resolutions below 1 m and resulting in approximately 5.0e8 degrees of freedom. Sixteen wind directions uniformly distributed over 360deg are simulated to capture the full directional response of the urban fabric.

Designing networks that minimize distances and satisfy structural constraints is a fundamental task across transportation, communication, and biological systems. Here, we consider the problem of finding, for a given degree sequence, the network structure displaying the smallest possible average shortest-path length. While exact solutions are available in linear time for trees, such an optimization problem becomes computationally infeasible as soon as loops are allowed in the networks. We propose a fast algorithm to construct approximate solutions to such a degree-constrained distance-minimization problem. Accordingly, edges are first created between high-degree nodes; then, additional connections are placed following the rules of the standard configuration model. In spite of its simplicity, the algorithm displays outstanding performance as demonstrated in our systematic experiments on both synthetic and real degree sequences. Our method is particularly effective on synthetic degree sequences displaying medium levels of heterogeneity. When applied to degree sequences of real networks, the proposed algorithm is able to reduce the all-pair shortest path of real structures by 20%, on average. We perform a validation on small-sized networks, where we compare the shortest-path distance of the networks generated with our algorithm against those obtained via simulated annealing optimization. Although simulated annealing yields slightly better structures, our proposed algorithm provides nearly identical solutions at a substantially lower computational cost, making it a solid method in applications concerning large-scale systems.

Quantum computational advantage is generally attributed to coherent interference and other non-classical resources, yet their respective roles remain difficult to disentangle in experimental platforms where multipartite entanglement is inherently present. High-dimensional quantum systems provide an attractive route for investigating these resources while simultaneously reducing hardware overhead for quantum information processing. Here we realize a programmable four-dimensional optical qudit encoded in a single trapped $^{138}\mathrm{Ba}^{+}$ ion and demonstrate universal coherent control through phase-programmable optical rotations. Using this platform, we implement an entanglement-free realization of Grover's quantum search algorithm, achieving target-state identification probabilities of up to $94.5\pm2.0\%$. Within the same processor, we further demonstrate state-dependent quantum contextuality through a Clauser–Horne–Shimony–Holt (CHSH)-type noncontextuality inequality, obtaining a maximum violation of $S = 2.816 \pm 0.082$, in close agreement with the Tsirelson bound. By integrating programmable quantum computation and contextuality measurements within a single multilevel trapped-ion platform, our work establishes a versatile architecture for investigating the relationship between coherent interference and contextuality in quantum information processing and provides a scalable route toward high-dimensional quantum technologies.

LumaCam detectors are a novel type of event-mode imaging detectors based on scintillator screens that have been developed recently for neutron imaging applications. They operate in an event-mode in which individual interactions of the incoming particles with the scintillator screen are reconstructed in both space and time, providing simultaneous high spatial and temporal resolution. In this work, we demonstrate the applicability of LumaCam detectors to X-ray and gamma-ray imaging. First tests with a 120 kV acceleration voltage X-ray source show a spatial detector resolution down to 50 um and the temporal resolution is estimated to be ~1 us. This combination makes LumaCam detectors especially suitable for imaging fast processes with high spatial resolution with limited cone beam magnification. The most significant adaption of the detector from the version for neutron detection is the scintillator screen. To further investigate the potential of LumaCam detectors for high-energy photon applications, additional measurements employing different scintillator screen materials have been carried out using gamma ray sources. The results show significant improvements in the temporal resolution with values as low as ~15 ns. In addition, some scintillators also show significant energy sensitivity in the photon multiplicity spectrum, highlighting the potential of LumaCam detectors for energy-selective X-ray and gamma-ray imaging.

Packet-switched quantum networks require buffers that can delay qubit payloads while routing information is read out in real time. Previous approaches have not provided this functionality in a fully fibre-integrated architecture compatible with telecom infrastructure. Here we demonstrate an optical-fibre-integrated buffer, based on a recirculating loop and a fibre storage line, in which the storage time of a polarisation-encoded qubit payload is determined by readout of an attached packet header. The key component behind this achievement is an ultra-low-loss poled fibre phase modulator, which provides fast, polarisation-insensitive switching directly in fibre and allows header and payload to be processed within the buffer. We demonstrate storage and retrieval of polarisation-encoded qubit payloads for storage times up to 47 $\mu$s, with an average quantum bit error rate of 1.8% together with stable operation over several hours. These results establish a practical fibre-based architecture for packet-level quantum network buffering that can easily integrate into the current telecommunication infrastructure opening up new paths for deployment of the quantum internet.

Structured light has emerged as a promising resource for high-capacity and secure free-space optical communication, where atmospheric turbulence remains a major source of signal degradation. In this work, we investigate the resilience of different transverse mode structures of an optical beam with respect to the random action of turbulence. A spatial light modulator (SLM) is programmed to apply amplitude and phase modulation corresponding to the desired transverse mode, which is then transmitted through a turbulent medium emulated by a second SLM. Laguerre-Gauss, Hermite-Gauss, and Airy beams are investigated through the resulting intensity distributions measured with a camera. Different figures of merit are used to evaluate and compare the resilience of these modes.

Long-term instabilities in astrophysical fluids are inherently nonlinear, where even small-amplitude perturbations can trigger dramatic instability. However, owing to the complex interactions among non-normal modes, the perturbation structures responsible for the greatest growth remain poorly understood. In this paper, we employ the nonlinear optimization method known as the conditional nonlinear optimal perturbation (CNOP) to identify the most dangerous initial velocity perturbation, i.e., the perturbation that maximizes the kinetic energy growth in the two-dimensional compressible Rayleigh-Taylor instability in astrophysical hydrodynamics. Compared with random perturbations, the optimal perturbation forms a coherent wave-packet structure localized around the density interface. We investigate its dependence on spatial resolution and optimization time horizon through two sets of numerical experiments. For a fixed optimization time, increasing the spatial resolution produces a more sharply localized wave packet, whereas for a fixed spatial resolution, increasing the optimization time causes the wave packet to become progressively more dispersed. Furthermore, we analyze the optimal perturbations in Fourier space using the fast Fourier transform (FFT), which provides a clearer characterization of the spectral distribution. Higher-resolution simulations concentrate most of the perturbation energy into only a few dominant modes, while longer optimization times distribute the energy over a broader range of modes. These results indicate that short optimization time horizons involve relatively weak modal interactions and remain closer to the linear regime, whereas longer optimization times enhance nonlinear modal interactions, broaden the spectral distribution, and reduce the predictive capability of linear stability theory.

In Jewish tradition, the boundary between days is not midnight, but nightfall. Nightfall is when one must pray ma'ariv, count the omer, and may engage in activity after Shabbat. While there are slightly different definitions of nightfall for Shabbat restrictions (Motsa'ei Shabbat) versus other purposes (Ts'eit HaKokhavim), most minhagim define nightfall to be when three stars of some specified size and proximity are visible in the sky. This definition presents some difficulty. Not only are these conditions difficult to define, they are further complicated by weather, cloud cover, and light pollution. Observant Jews therefore usually approximate these times by defining nightfall to be when the sun has reached a certain distance below the horizon. Although these approximations have been effective, modern astronomy enables us to calculate precisely when these conditions are met. This work applies these techniques to calculate the time of Ts'eit HaKokhavim and Motsa'ei Shabbat evaluates the accuracy of the approximations, and explores the effects of light pollution on these times. While Ts'eit HaKokhavim is reasonably well-approximated by standard methods, the conditions for Motsa'ei Shabbat generally occur after the time predicted by the approximations. Light pollution does not shift Ts'eit HaKokhavim by more than a minute but significantly changes Motsa'ei Shabbat. In fact, light pollution causes the conditions of Motsa'ei Shabbat to never be met on at least some nights in every population center. Finally, I provide a tool (halakhic-nightfall.streamlit.app) for calculating Ts'eit HaKokhavim and Motsa'ei Shabbat at an arbitrary time and location on Earth.

General Relativity (GR) can be effectively examined in the low-velocity, weak-field limit, where its inherently tensorial structure simplifies to a vector-based formulation closely analogous to classical electrodynamics. This correspondence becomes particularly clear when both theories are expressed within a field-free, interaction-based framework, in which the leading relativistic corrections emerge naturally as velocity- and acceleration-dependent modifications to the static interaction. As a result, several predictions of GR can be derived using familiar techniques from electrodynamics, provided the relevant phenomena remain within the regime of validity of the approximation. This structural analogy facilitates a conceptual understanding of GR enabling the introduction of its core ideas even in an introductory level course, the single exception being the treatment of radiation, which requires tools at more advanced level. Building on this pedagogical framework, the incorporation of special relativity (SR) and the equivalence principle enables concise and transparent derivations of gravitational time dilation, as well as its immediate consequences, including light deflection and gravitational frequency shifts. A detailed exposition of this material is provided in the supplementary material.

One challenge in science communication is how to engage audiences with highly abstract scientific fields often perceived as distant, technical, or inaccessible. This Practice Insight examines two initiatives implemented during the International Year of Quantum Science and Technology: Quantum Fest in Japan and Quantum100 in Germany, which together attracted more than 4000 participants. Both employed immersive artistic experiences, including music, visual art, and embodied participation to create alternative entry points into quantum physics. Drawing on post-event surveys, participant comments, and stakeholder interviews, this paper identifies three dimensions of resonance: sensory immersion and reduced psychological barriers, collective embodied meaning-making, and emerging transformative engagement. The findings suggest that resonance-driven approaches can complement explanation-centred science communication by enabling audiences to form meaningful relationships with science before, alongside, or beyond conceptual understanding.

The centre-mode elastic instability, prevalent in rectilinear flows of dilute polymer solutions, allows dynamic states to emerge even in the absence of inertia. Here, we show that this instability can be significantly enhanced when the base flow has a nonuniform spatial-distribution of polymers. In such a flow, the polymeric stress not only depends on the conformation tensor (determined here by the Oldroyd-B equation) but also varies proportionally with the polymer concentration field, which satisfies a scalar transport equation. Focusing on the inertialess Stokes limit, we first consider the simple setting of periodic Kolmogorov flow. A linear stability analysis shows that a nonuniform polymer concentration either promotes or suppresses the centre-mode instability, depending on whether the polymers are localised near or away from the maximum of the base-velocity profile. We then focus on a base flow with a distinct polymer-laden stream overlying the base-velocity maximum, and sandwiched between polymer-free streams. We find that the critical Weissenberg number (product of the elastic relaxation time and the typical strain-rate) at the onset of instability undergoes a sudden decrease as the total polymer loading is increased. An energy analysis attributes this destabilisation to elastic feedback forces that arise from concentration gradients near the interfaces between the polymer-laden and polymer-free streams. The insights from Kolmogorov flow are shown to carry over to channel flow, where localising polymers about the centreline strongly promotes the centre-mode instability.

We present a theory of the collective tunnel effect in atomic systems subject to strong low-frequency laser fields. Using an analytic semi-classical method and numerical solution to the time-dependent Schrödinger equation we demonstrate the collective channel of the nonsequential double ionization in a model two-dimensional two-electron system with ionization potentials reproducing those of neutral xenon and of the negative bromine ion. Collective tunneling in the presence of the electron-electron repulsion comprises the joint sub-barrier motion of the two electrons along quantum trajectories transversely shifted in opposite directions with respect to the direction of the external electric field. Analytic results for the rates of collective tunneling allow indicating the intervals of laser intensity, where this effect can be expected to compete with sequential tunneling in helium, xenon, and negative bromine. Momentum distributions of the electron pairs carry clear signatures of the collective channel in the form of shoulders in the direction lateral to the field polarization.

We study reduced-order modeling for inverse problems in layered media, focusing on the recovery of impedance profiles from time-domain measurements. Using the Goupillaud structure, we formulate the forward problem as a discrete dynamical system and introduce a ROM-based objective defined at the level of reduced operators. Through numerical experiments on a 5-layer medium under various structured perturbations, we compare the ROM-based objective with a classical data misfit. The results show that the ROM-based inversion provides a more favorable reconstruction in the clean setting and in certain structured perturbation regimes, while remaining consistently competitive with the classical approach across all cases considered.

We study the time-dependent Maxwell system, formulated in the sense of distributions, for electromagnetic waves propagating through media with temporal and spatial material interfaces. Under explicit trace and regularity assumptions on the permittivity and permeability, we derive the jump conditions produced by temporal discontinuities and by subsequent spatial interfaces. These conditions are used to obtain generalized Snell laws for the wave vectors generated by temporal splitting, reflection, and transmission. We also derive the associated amplitude equations and organize them as a finite-dimensional linear system for a space-time slab geometry. Finally, we provide an explicit oblique-incidence example. Our approach does not impose a smooth-field ansatz and allows material parameters that need not be constant away from the interfaces.

Over the last decade, epsilon-near-zero (ENZ) photonics has been driven by the search for lower losses and stronger nonlinear responses. Here, I ask a different question: can crystal symmetry also be used to shape the ENZ response? I focus on low-symmetry conductors, where the geometry of the electronic states can produce electric currents that are not present in ordinary Drude materials. These currents may enable polarization-dependent gain, nonreciprocal effects, and ultrafast nonlinearities controlled by symmetry and an external bias. I suggest that such materials may be useful for active and time-varying nanophotonics.

Protons and neutrons are the smallest forms of measurable matter, and each nucleon has 3 up (+2/3) and down (-1/3) quarks. Quarks treated as point-like particles within polygonal geometries model the structures of stable nuclides through $^{36}$Ar. The model derives from the proton's radius (r=0.8414 fm), the hadron's prolate spheroid shape (from the $\Delta(1232)$ resonance), and the separation distance between bound nucleons ($\approx$0.8 fm, from the Argonne $v_{18}$ $NN$ potential). The prolate nucleon's spatial extent arises from its 3 quarks, which implies a qualitatively linear quark sequence. Spin-spin forces repel the like-flavored quarks to opposite ends of the nucleon, leaving the unlike quark in the middle. Quark-to-quark distance within the nucleon corresponds to the nucleon's radius. Nucleons link by quark-to-quark interactions to form proton-neutron short-range correlated pairs (pn SRC pairs), separated by a distance equal to the proton's radius. Alternating nucleons produce regularly alternating up/down quark sequences. We contemplate structures for each stable nuclide through $^{36}$Ar and include the one whose rotational radius (from the regular polygon radius formula) best correlates with its accepted charge radius (r(31)=0.98, p<0.001). Nucleon alternation makes pn SRC pairs and produces the equal numbers of protons and neutrons (Z=N) in the isotopes $^{4}_{2}$He, $^{12}_{6}$C, $^{14}_{7}$N, $^{16}_{8}$O, $^{20}_{10}$Ne, $^{24}_{12}$Mg, $^{28}_{14}$Si, and $^{32}_{16}$S, comprising 99.5% of stable baryonic matter. Bilateral structural symmetry emerges as a sensitive and specific predictor of cosmic abundance. Opposing deuteron-deuteron alternating quark charge sequences produce alternating and unequal electromagnetic fields capable of modelling the close-range attraction and far-range repulsion of the fusion potential curve and Coulomb potential energy barrier.

A Thomson parabola ion spectrometer (TPIS) has been designed and developed for diagnostics of laseraccelerated ion beams in the MeV energy range. The TPIS has been validated by ion acceleration experiment at petawatt laser facility. Necessary simulations to evaluate the electric and magnetic field distributions have been performed with the help of a numerical simulation software to aid the selection of the spectrometer geometry while minimising fringe-field effects. Analytical dispersion expressions have been formulated from the simulations that take into account the spatial variation in the electromagnetic field profiles. The ion deflections obtained from these expressions demonstrate an improved agreement with experimentally measured proton trajectories compared to the case when constant fields are considered. The TPIS hence fabricated in-house has been subject to magnetic field measurements, which are in excellent agreement with the simulated field profile. The TPIS has the provision to change the field-free drift region, showcasing flexibility to be employed over a broad energy range and with different experimental setups. The spectrometer has been subsequently used for detecting laser-accelerated ion beams from thin aluminum foil targets. These experiments have demonstrated the capability of the spectrometer to resolve multiple ion species with sufficient separation between them. The developed TPIS provides a compact, flexible and accurate diagnostic for high-energy laser-plasma experiments.

Accurate precipitation forecasting remains one of the most challenging problems in weather prediction. While recent AI weather prediction (AIWP) systems have achieved substantial improvements in medium-range forecasting skill, precipitation often remains a secondary target and is commonly learned from reanalysis datasets that contain considerable uncertainty. In this work, we investigate two complementary strategies for improving AI-based precipitation forecasts. Building on the Prithvi-WxC foundation model, we develop Prithvi-Precip, a global precipitation forecasting system, and examine (1) the impact of training targets derived from satellite-based precipitation estimates rather than reanalysis fields and (2) the direct assimilation of satellite observations into the forecasting model. We systematically evaluate key design choices for finetuning the Prithvi-WxC AI foundation model for precipitation forecasting. We find that autoregressive rollout training produces substantially more accurate forecasts than direct conditioning on forecast lead time. Using independent radar-based precipitation estimates for evaluation, we show that training on satellite-derived precipitation targets yields improved forecast accuracy relative to training on MERRA-2 precipitation fields. Furthermore, direct ingestion of satellite observations provides additional improvements at short lead times, with the largest gains occurring in tropical and subtropical regions. Together, these advances enable Prithvi-Precip to substantially improve upon directly comparable precipitation forecasts from the Goddard Earth Observing System. Our results highlight the potential of improved precipitation targets and the direct integration of satellite observations as promising pathways for advancing medium-range AI precipitation forecasting.

The degree of cross-polarization (DoCP) and the electromagnetic degree of coherence (EM DoC) of an electromagnetic beam are investigated at the observation points for incoherent and non-uniformly polarized, i.e., different degree of polarization with respect to space at the two pinholes in Young's interference experiment. We note that DoCP at the observation plane can be expressed as the average value of the degree of polarization at the pinholes of Young's interference experiment. The present study also verifies that the DoCP is a two-point generalization of the DoP. Additionally, EM DoC at observation points can be controlled by DoP at pinholes. The findings may be useful for classical ghost imaging, lensless imaging, and the study of Stokes correlations.

We present a table-top cryogenic ultrafast broadband XUV absorption spectroscopy (c-UBXAS) beamline designed for temperature-dependent and time-resolved investigations of quantum materials. The instrument combines a broadband high-harmonic generation source spanning 22-73 eV with automated image registration and cryogenic sample control down to 20 K, enabling element-specific measurements under both equilibrium and nonequilibrium conditions. The beamline provides sub-50-meV energy resolution and a sub-10-fs instrument response function, while maintaining long-term stability suitable for extended, ultrasensitive measurements. Benchmark experiments on NiI$_2$, a van der Waals multiferroic, reveal temperature-dependent spectral evolution across its magnetic phase transitions, demonstrating the ability to identify element-specific contributions to the ground state and its transient response in the femtosecond regime. This instrument introduces the opportunity to unravel the very first response of a solid-state material during light-matter interaction, paving the way for understanding the complex phase space of nonequilibrium dynamics and emergent states in strongly correlated systems where the few-femtosecond electronic response has eluded most other types of time-resolved techniques.

Integrated photon-pair sources are a core component of chip-based quantum computing, communication, and metrology. Although such sources have been demonstrated at conventional telecom wavelengths, the 2 $\mu$m band remains comparatively less explored, despite offering advantages for free-space quantum communication, low-loss transmission in emerging fiber networks, and integration with silicon photonic platforms. In this paper, we demonstrate spontaneous parametric down-conversion (SPDC) in straight GaAs- and AlGaAs-on-insulator waveguides. This platform offers strong second-order nonlinearity and geometry-tunable dispersion, which are advantageous for efficient on-chip pair generation. Measurements of the joint spectral intensity and heralded second-order correlation function show broadband emission around 2 $\mu$m with strong spectral anti-correlations. To our knowledge, this is the first direct joint-spectral characterization of an integrated SPDC source in this wavelength regime.

Rare-earth ions in crystals are useful in precision measurements and quantum information science because of their exceptional optical and spin coherence properties. We show that the nuclear spin coherence time of $^{153}\mathrm{Eu}^{3+}$ ions doped into yttrium orthosilicate can be significantly enhanced by driving the $^{89}\mathrm{Y}$ nuclear spins in the host crystal. This improvement in spin coherence time opens up ways to improve the precision of measurements using rare-earth-doped crystals.

Gaussian wavepacket (GWP) methods are prevalent means of solving the nuclear time-dependent Schrodinger equation (TDSE) on classical computers. They consist of representing the nuclear wave function as a superposition of Gaussians. Here, we present a variational hybrid continuous-variable discrete-variable (CV-DV) algorithm for simulating adiabatic nuclear dynamics on qubit-oscillator quantum hardware. It encodes a superposition of frozen Gaussians (FGs) onto the qubit-oscillator register and evolves it according to the time-dependent variational principle (VP). We test two variants of the approach, one that evolves a single FG and another that evolves a superposition of FGs, on a set of prototypical 1D harmonic and anharmonic systems. We simulate the photoexcited state dynamics of SO2 using the single FG variant of the algorithm and compute its autocorrelation function on physical quantum hardware. For harmonic and Morse potentials, the variant evolving the superposition of FGs converges to the numerically exact solution as the number of Gaussians increases. In the case of the double-well potential, the algorithm simulates wavepacket bifurcation and recurrence correctly, and the ensuing irregular dynamics moderately well. Overall, this work establishes a pathway for simulating molecular dynamics on noisy intermediate-scale quantum devices.

Local detailed balance restricts transport by self-propulsion in static activity landscapes. We show that a delayed speed adaptation (“delayed motility/kinesis”) generically breaks this symme try, inducing directed transport in asymmetric periodic motility profiles and enhancing diffusion in symmetric ones. Both effects occur for run-and-tumble, active Brownian, and inertial active particles, without requiring potential interactions, walls, imposed gradients, higher dimensions, or translational diffusion. Their magnitudes, and even current reversals, are conveniently tuned via the delay time, which establishes delayed motility as a versatile generic and experimentally accessible mechanism for autonomous self-steering and transport control in motile-active-matter circuity.

In this work, we derive closed-form expressions for multi-time correlation functions underlying higher-order nonlinear spectroscopic response functions within the harmonic approximation. Our method includes displacements, frequency changes, and Duschinsky rotation between the vibrational modes of different electronic states while retaining polynomial scaling with the number of degrees of freedom. Finite temperature is accounted for without summation over vibrational eigenstates. To show the capabilities of our method, we apply it to calculate fifth-order two-dimensional resonance Raman (2DRR) spectra of two-mode model systems and naphthalene. Comparison with the displaced harmonic oscillator model shows that Duschinsky rotation modifies the positions and relative intensities of diagonal and cross peaks. Overall, our results demonstrate that 2DRR spectroscopy is particularly sensitive to changes in normal coordinates between electronic states and can provide distinct signatures of Duschinsky coupling in molecular systems.

Tomographic emissivity reconstruction from plasma diagnostics data relies on a synthetic model mapping the plasma emissivity to the measured signals. The model, referred to as a geometry matrix in the plasma imaging community, is often built using the line-of-sight (LoS) approximation. This approximation neglects the finite width of the detector viewing beams and can therefore introduce systematic errors. Physically correct volume-of-sight (VoS) models remove this inaccuracy by accounting for the full 3D extent of the viewing beams. Their adoption, however, is sometimes hindered by the difficulty of independently validating them. We present an intuitive and easily inspectable voxel-to-detector (V2D) approach for computing physically accurate VoS geometry matrices, based on discretizing the tokamak vessel into voxels and estimating the contribution of each voxel to the measurements of each detector. We apply the V2D approach to the soft X-ray (SXR) and bolometry systems of the TCV tokamak. Through phantom-based studies on physically realistic emissivity profiles, we quantify the improvement in reconstruction quality obtained by using VoS rather than LoS models. We find that the VoS model yields overall better accuracy and precision; however, interestingly, the simpler LoS model does not introduce a significant systematic bias in the estimated total, core, divertor and main chamber radiated powers. We further compare the V2D geometry matrix with an independent ray-tracing implementation, finding excellent agreement that validates both approaches for routine use at TCV. All routines developed in this work are made openly available.

4H-SiC has emerged as a third-generation chip material because its superior thermal conductivity and high breakdown field enable the material to achieve high power density and higher switching frequencies in power-electronics applications. As chip architectures evolve toward 3D and heterogeneous integration, the mechanical and thermal design space tightens while yield risks grow. In particular, advanced packages require mid-process wafer thinning to < 100 $\mu$m to shorten interconnects and control thermo-mechanical stress. Femtosecond laser slicing for 4H-SiC wafers offers a non-contact processing approach to produce thin layers with low defects, while strong optical nonlinearities obscure the relationship between the laser parameters and the resulting slicing quality. Here, we systematically investigate Kerr-induced self-focusing using a femtosecond laser in 4H-SiC slicing by combining experiments, a semi-empirical analytical model, and numerical ray optics simulations. We demonstrate that the interplay between pulse energy and processing depth governs the self-focusing behavior, which directly correlates with post-separation surface texture parameters and separation stress, thereby linking nonlinear beam propagation to slicing quality. Based on this relationship, we define a processability map in the pulse energy with self-focusing depth space over a normalized irradiance background. Analytically, the model extends the Marburger formula to focused beams by replacing the power ratio with a normalized irradiance. Ray optics simulations capture the geometric features at the self-focusing point and are validated against experimental observations. Within physically defined thresholds, the processability map directly connects laser parameters to separation stress and surface texture metrics, providing practical guidance for depth control beyond trial-and-error.

The vast tropical Pacific is home to the majority of tropical cyclones (TCs) which threaten the rim countries every year. The TC genesis is nourished by warm sea surface temperatures (SSTs). During El Niño, the western Pacific warm pool extends eastward. However, the number of TCs does not increase significantly with the expanding warm pool and it remains comparable between El Niño and La Niña. Here, we show that the subsurface heat content change counteracts the favorable SSTs in the tropical central-north Pacific. Due to the anomalous positive wind stress curl, the 26 {\deg}C isotherm shoals during El Niño over this region and the heat content diminishes in the tropical central-north Pacific, even though warm SST anomalies prevail. This negative correlation between SST and 26 {\deg}C isotherm depth anomalies is opposite to the positive correlation in the tropical eastern and western Pacific. This is critical because quantifying the dynamics of the subsurface ocean provides insight into TC genesis. The trend in TC genesis continues to be debated. Future projections must account for the net effect of the surface-subsurface dynamics on TCs, especially given the expected El Niño-like pattern over the tropical Pacific under global warming.