Chemical Physics · Cross-listed from quant-ph
Cost-effective scalable quantum error mitigation for tiled Ansätze
Oskar Graulund Lentz Rasmussen, Erik Kjellgren, Peter Reinholdt et al. (+4 more)
We introduce a cost-effective
quantum error mitigation technique that builds upon the recent Ansatz-based gate and readout error mitigation method (M0). The technique, tiled M0, leverages the unique structure of tiled Ansätze (e.g., tUPS, QNP, hardware-efficient
circuits) to apply a locality approximation to M0 that results in an exponential reduction in the QPU cost of the noise characterization. We validate the technique for molecular ground state energy calculations with the tUPS Ansatz on LiH, molecular hydrogen, water, butadiene, and benzene (4-12
qubits), demonstrating little to no loss in accuracy compared to M0 in noisy simulations. We also show the performance of the technique in
quantum experiments, highlighting its potential use in near-term applications.
Read the full abstract ▾
All authors Oskar Graulund Lentz Rasmussen, Erik Kjellgren, Peter Reinholdt, Stephan P. A. Sauer, Sonia Coriani, Karl Michael Ziems, Jacob Kongsted
Optics
Mapping Nonlinear Mode Interactions in Coupled Kerr Resonators
Luca O. Trinchão, Luiz Peres, Eduardo S. Gonçalves et al. (+6 more)
We present a method for resolving spatial mode overlaps in coupled microresonators based on Kerr and thermal cross-phase modulation. Through a pump-probe setup, we measure experimental overlap in a three-ring resonator with good agreement with analytical theory. Our technique can be generalized for describing nonlinear interactions in more complex multi- and coupled-mode systems.
Read the full abstract ▾
All authors Luca O. Trinchão, Luiz Peres, Eduardo S. Gonçalves, Miguel Nienstedt, Laís Fujii dos Santos, Paulo F. Jarschel, Thiago P. M. Alegre, Nathalia B. Tomazio, Gustavo S. Wiederhecker
Fluid Dynamics · Cross-listed from math.NA
A p-adaptive high-order mesh-free framework for fluid simulations in complex geometries
Ruofeng Feng, Jack R. C. King and Steven J. Lind
This paper presents a novel p-adaptive, high-order mesh-free framework for the accurate and efficient simulation of fluid flows in complex geometries. High-order differential operators are constructed locally for arbitrary node distributions using linear combinations of anisotropic basis functions, formulated to ensure the exact reproduction of
polynomial fields up to the specified p order. A dynamic p-refinement strategy is developed to refine (increase) or de-refine (decrease) the
polynomial order used to approximate derivatives at each node. A new refinement indicator for mesh-free methods is proposed, based on local error estimates of the
Laplacian operator, and is incorporated into the solution procedure at minimal added computational cost. Based on this error indicator, a refinement criterion is established to locally adjust the
polynomial order p for the solution. The proposed adaptive mesh-free scheme is then applied to a range of canonical PDEs, and its potential is demonstrated in two-dimensional simulations of a compressible reacting flow in porous media. For the test cases studied, the proposed method exhibits potential to save up to 50% of computational costs while maintaining the specified level of accuracy. The results confirm that the developed p-adaptive high-order mesh-free method effectively captures highly non-linear regions where high-order approximation is necessary and reduces computational costs compared to the non-adaptive method, preserving high accuracy and solution stability.
Read the full abstract ▾
Optics
Flexible mm-Wave Frequency and High-Speed Arbitrary IQ Signal Synthesis by a Photonic System on Chip
Bowen Zhu, Tao Zhu, Yazhi Pi et al. (+5 more)
Photonics-assisted millimeter-wave bands and terahertz signal generation offer significant advantages over traditional electronic methods by leveraging the inherent benefits of optical components, including broad bandwidth, low power consumption, and minimal insertion loss. This work utilizes a silicon photonic chip in conjunction with a reconfigurable optical frequency comb to demonstrate the synthesis of signals in the millimeter-wave range. The implemented photonic system performs on-chip filtering and modulation, producing high-bandwidth single frequency, multi-frequency, and vector signals suitable for arbitrary IQ signal construction. These results highlight the flexible and reconfigurable capabilities of the proposed approach, providing new perspectives for applications in
radio-over-fiber systems and beyond.
Read the full abstract ▾
All authors Bowen Zhu, Tao Zhu, Yazhi Pi, Chunyang Ma, Xiaochuan Xu, Zizheng Cao, Lei Wang, Shaohua Yu
Fluid Dynamics
The effect of tip-speed ratio and free-stream turbulence on the coupled wind turbine blade/wake dynamics
Francisco J. G. de Oliveira, Martin Bourhis, Zahra Sharif Khodaei et al. (+1 more)
Wind turbines operating within wind farms experience complex aerodynamic loading arising from the interplay between wake-induced velocity deficits, enhanced
turbulence, and varying operational conditions. Understanding the relationship between the blade's structural response to the different operating regimes and flow structures generated in the turbine's wake is critical for predicting fatigue damage and optimizing turbine performance. In this work, we implement a novel technique, allowing us to simultaneously measure spatially distributed blade strain and wake dynamics for a model wind turbine under controlled free-stream
turbulence (FST) and tip-speed ratio ($\lambda$) conditions. A $1$ $\mathrm{m}$ diameter three-bladed rotor was instrumented with distributed Rayleigh backscattering fibre-optic sensors, while synchronised hot-wire anemometry captured wake
evolution up to $4$ rotor diameters downstream. Experiments were conducted covering a wide $\{\mathrm{FST}, \lambda\}$ parameter space – $21$ cases in total. Results reveal that aerodynamic-induced strain fluctuations peak at $\lambda \approx 3.5$, close to the design tip -speed ratio ($\lambda_d = 4$), with the blade's tip experiencing a contribution from the aerodynamically-driven strain fluctuations of up to $75\%$ of the total fluctuating strain at design conditions. Spectral analysis shows frequency-selective coupling between wake flow structures and the blade response, dominated by flow structures dynamically related to the rotor's rotating frequency (eg. tip
vortex structure). The novel experimental methodology and results establish a data-driven foundation for future aeroelastic models' validation, and fatigue-informed control strategies.
Read the full abstract ▾
All authors Francisco J. G. de Oliveira, Martin Bourhis, Zahra Sharif Khodaei, Oliver R. H. Buxton
Optics
Simultaneous generation of Raman-assisted Soliton Microcombs and Tunable Multi-chromatic Raman Microlasers in Single Monolithic Thin-film Lithium Niobate Microrings
Yingnuo Qiu, Renhong Gao, Chuntao Li et al. (+9 more)
High-performance integrated broadband coherent light sources are essential for advanced applications in high-bandwidth data processing and chip-scale metrology, yet remain challenging. In this study, we demonstrate a monolithic Z-cut lithium niobate on
insulator (LNOI) microring platform that enables simultaneous generation of tunable multi-chromatic microlasers and Raman-assisted
soliton microcombs. Exploiting the strong Raman activity and high second-order nonlinearity of LNOI, we engineered a dispersion-optimized microring with a loaded Q factor of 3.86X10^6, facilitating on-chip efficient broadband coherent light source. A novel phase-matching configuration with all the waves of the same ordinary polarization was realized for the first time in this platform, feasibly enabling modal-phase matched Raman-quadratic nonlinear processes that extend lasing signals into the visible spectrum. Under continuous-wave
laser pumping at 3.73 mW in the telecom band, we achieved a Raman-assisted
soliton comb centered at 1624.49 nm with record-low pump threshold on the LNOI platform. Concurrently, multi-chromatic Raman lasing outputs were observed at ~1700, ~813, and ~535 nm within the same microring. The system exhibited efficient wavelength tuning of these multi-chromatic
laser signals through a 5 nm shift in pump wavelength. This work represents a significant advance in integrated photonics for versatile optical signal generation.
Read the full abstract ▾
All authors Yingnuo Qiu, Renhong Gao, Chuntao Li, Yixuan Yang, Xinzhi Zheng, Guanghui Zhao, Xiaochao Luo, Qifeng Hou, Lingling Qiao, Min Wang, Jintian Lin, Ya Cheng
Geophysics
When barchan dunes move over craters
Paulo Vitor Ribeiro Plácido, Danilo da Silva Borges, Willian Righi Assis et al. (+1 more)
We investigate the possible outcomes of a subaqueous barchan moving over a crater-like depression in the bed. For that, we carried out experiments where we varied the dune size, crater and grain diameters, and flow velocities. We found that subaqueous barchans can be blocked, destroyed, or pass over craters, with transitional situations, and that strong instabilities take place under some conditions. Based on a dune-crater size ratio and a modified Stokes number, we propose a map that classifies the different outcomes of interactions. If used with caution, the map can serve as a reference for understanding the much slower behavior of dunes migrating over or near craters on the surface of Mars.
Read the full abstract ▾
All authors Paulo Vitor Ribeiro Plácido, Danilo da Silva Borges, Willian Righi Assis, Erick de Moraes Franklin
Medical Physics
Strategic Development of a Hydrogen Supply Chain in Corsica: a Multi-criteria Analysis
Tchougoune Moustapha Mai, Mohamed Hajajji, Catherine Azzaro-Pantel et al. (+2 more)
A multi-objective framework for hydrogen supply chain (HSC) planning is developed for island contexts, incorporating Mixed-Integer Linear Programming (MILP) over multiple time periods. The model minimizes total system cost, greenhouse gas (GHG) emissions, and a risk index criteria. The case study of Corsica is considered, using Geographic Information Systems (GIS) for spatial analysis and infrastructure locating. The 2050 future design of the HSC is determined including site selection, capacity sizing, and technology choices. The proposed m-TOPSIS-based multi objectives solution shows a decentralized infrastructure with a levelized cost of hydrogen of ___6.55/kg, and greenhouse gas emissions under 2 kgCO___e/kg H___. The study also integrates water availability and tourism-induced demand variation as key drivers of energy planning in insular regions.
Read the full abstract ▾
All authors Tchougoune Moustapha Mai, Mohamed Hajajji, Catherine Azzaro-Pantel, Maude Chin Choi, Christian Cristofari
Chemical Physics
Different Rise Times of Atomic Br M$_{4,5}$ 3d$_{3/2,5/2}$ Core Level Absorptions during Br$_{2}$ C $^{1}\Pi_{u}$ $1_{u}$ State Dissociation via Extreme Ultraviolet Transient Absorption Spectroscopy
John E. Beetar, Jen-Hao Ou, Yuki Kobayashi et al. (+1 more)
The reported ”dissociation times” for the Br$_{2}$ C ($^{1}\Pi_{u}$ $1_{u}$) state by various measurement methods differ widely across the literature (30 to 340 fs). We consider this issue by investigating attosecond extreme ultraviolet (XUV) transient absorption spectroscopy at the Br M4,5 3d$_{3/2,5/2}$ edges (66 to 80 eV), tracking core-to-valence (3d to 4p) and core-to-Rydberg (3d to ns, np, n $\geq$ 5) transitions from the molecular to atomic limit. The progress of dissociation can be ascertained by the buildup of the atomic absorption in time. Notably, the measured rise times of the 3d$_{3/2,5/2}$ to 4p transitions depend on the probed core level final state, 38 $\pm$ 1 and 20 $\pm$ 5 fs for $^{2}$D$_{5/2}$ and $^{2}$D$_{3/2}$ at 64.31 and 65.34 eV, respectively. Simulations by the
nuclear time-dependent Schrödinger equation reproduce the rise-time difference of the 3d to 4p transitions, and the theory suggests several important factors. One is the transition dipole moments of each probe transition have different molecular and atomic values for $^{2}$D$_{5/2}$ versus $^{2}$D$_{3/2}$ that depend on the bond length. The other is the merger of multiple molecular absorptions into the same atomic absorption, creating multiple timescales even for a single probe transition. Unfortunately, the core-to-Rydberg absorptions did not allow accurate atomic Br buildup times to be extracted due to spectral overlaps with ground state bleaching, otherwise an even more comprehensive picture of the role of the probe state transition would be possible. This work shows that the measured probe signals accurately contain the dissociative wavepacket dynamics but also reveal how the specific probe transition affects the apparent progress toward dissociation with bond length. Such potential probe-transition-dependent effects need to be considered when interpreting measured signals and their timescales.
Read the full abstract ▾
All authors John E. Beetar, Jen-Hao Ou, Yuki Kobayashi, Stephen R. Leone
Plasma Physics · Cross-listed from astro-ph.HE
Impact of Cosmic Ray Distribution on the Growth and Saturation of Bell Instability
Saikat Das, Siddhartha Gupta and Prateek Sharma
Cosmic rays (CRs) streaming in weakly magnetized
plasmas can drive large-amplitude
magnetic fluctuations via nonresonant streaming instability (NRSI), or Bell instability. Using one-dimensional kinetic simulations, we investigate how mono-energetic and power-law CR momentum distributions influence the growth and saturation of NRSI. The linear growth is governed solely by the CR current and is largely insensitive to the CR distribution. However, the saturation depends strongly on the CR distribution and is achieved through CR isotropization, which quenches the driving current. Mono-energetic CRs effectively amplify the
magnetic field and isotropize. For power-law distributions, the lowest-energy CRs dominate current relaxation and
magnetic growth, while the highest-energy CRs remain weakly scattered, limiting their contribution to saturation. In the absence of low-energy CRs, high-energy particles amplify
magnetic fields effectively and isotropize. Accounting for these effects, we provide a modified saturation prescription valid for both relativistic and nonrelativistic CRs. We propose a layered CR-confinement scenario upstream of astrophysical shocks, relevant to particle acceleration to high energies.
Read the full abstract ▾
Optics
Hybrid Si-GST Polarization-Insensitive Dynamically Tunable Bifocal Metalens Operating at 1.55-$\mu$m Wavelength
Dipika Rani Nath, Sadid Muneer and Sajid Muhaimin Choudhury
Metasurfaces have become a cornerstone of flat-optics, enabling precise control over light propagation through nanoengineered materials. Dynamic and reconfigurable metalenses are key to next-generation flat-optics platforms, yet their practical realization remains limited by slow response, optical loss, and polarization sensitivity. The integration of chalcogenide phase-change materials with metasurface architectures offers a powerful platform for dynamic optical tunability, owing to materials such as Ge$_2$Sb$_2$Te$_5$ (GST) that can be reversibly switched between amorphous and crystalline states with distinct refractive indices. However, the strong optical absorption of crystalline GST in the visible to near-infrared range has hindered its widespread use in reconfigurable metalenses. In this study, we design an all-dielectric polarization-insensitive metasurface based on hybrid Si-GST nanostructures to realize a dynamically tunable bifocal metalens operating at 1.55 \textmu m. The device achieves a variable focal length from 70 \textmu m to 200 \textmu m, with focusing efficiencies of 30% in the amorphous state and 20% in the crystalline state, as validated through finite-difference time-domain (FDTD) simulations. Using COMSOL Multiphysics, we show that flat-top
laser excitation enables uniform, reversible phase transitions within tens of nanoseconds, amorphization in ~8 ns and crystallization in ~90 ns, without mechanical motion or electrical bias. For next-generation metasurfaces intended for uses including beam steering, dynamic holography, optical routing, multi-depth imaging, and optical communication, this method shows great promise due to its control and stability.
Read the full abstract ▾
Fluid Dynamics
First-order buoyancy correction of modal instabilities in stratified boundary layers
Pietro Carlo Boldini, Ryo Hirai, Benjamin Bugeat et al. (+1 more)
We present a perturbation-based framework that captures buoyancy effects on modal instabilities in stratified boundary-layer flows within the fully compressible, non-Oberbeck-Boussinesq formulation. Treating the Richardson number as a small parameter and recasting the stability problem into an adjoint-residual form, we derive a first-order correction for the
eigenvalues using only the neutrally buoyant
eigenvalue problem. This eliminates the need to re-solve the
eigenvalue problem at each stratification level. For ideal-gas boundary layers, the framework accurately predicts how stable and unstable stratification modifies Tollmien-Schlichting waves, from growth rates and eigenfunctions to $N$-factors, holding across a wide range of Prandtl numbers, temperature ratios, and Mach numbers. Notably, the buoyancy sensitivity varies strongly with Prandtl number, revealing that for a given Richardson number, buoyancy can switch from destabilising to stabilising depending on the fluid. Beyond ideal-gas conditions, we apply the first-order buoyancy correction to strongly stratified boundary layers with supercritical fluids, where the phase relationship between density and velocity perturbations determines whether buoyancy stabilises or destabilises the underlying instability. The resulting $N$-factors demonstrate, for the first time, that buoyancy significantly affects transition predictions under pseudo-boiling conditions.
Read the full abstract ▾
All authors Pietro Carlo Boldini, Ryo Hirai, Benjamin Bugeat, Rene Pecnik
Optics
Passage of neutrons through accelerating crystal and the acceleration effect
A.I. Frank, V.A. Bushuev, M.A. Zakharov et al. (+1 more)
The problem of changing the energy of a
neutron when it passes through an accelerating
crystal under conditions close to the Bragg condition is considered. It is shown that, similar to the case of the passage of long-wavelength
neutrons through a refractive sample, the accelerated motion of a
crystal results in a change in
neutron energy. The physical nature of the phenomenon in both cases is determined by the difference in the Doppler frequency shift at the entrance and exit of the wave through the sample. The difference between the case of ordinary refraction of long-wavelength
neutrons and the case of wave passage through a
crystal under conditions where diffraction has a dominant influence on the nature of wave propagation is only quantitative. The results obtained are qualitatively consistent with the available experimental data.
Read the full abstract ▾
All authors A.I. Frank, V.A. Bushuev, M.A. Zakharov, G.V. Kulin
Computational Physics · Cross-listed from cond-mat.stat-mech
Quantum Hard Spheres with Affine Quantization
Riccardo Fantoni
We study a fluid of
quantum hard-spheres treated with affine-quantization. Assuming that the fluid obeys to Bose-Einstein statistics we solve for its thermodynamic properties using the path integral Monte Carlo method.
Physics Education
Particle Builder A Board Game for the Teaching of the Standard Model of Particle Physics at a Secondary Level
Lachlan McGinness, Yutong Ma, Mohammad Attar et al. (+14 more)
We present Particle Builder, an online board game which teaches students about concepts from the Standard Model of Particle Physics at a high school level. This short activity resulted in a gain of 0.16, indicating that students learned a significant amount of particle physics knowledge. Students found the activity was more engaging and less difficult than a normal classroom lesson.
Read the full abstract ▾
All authors Lachlan McGinness, Yutong Ma, Mohammad Attar, Andrew Carse, Yeming Chen, Thomas Green, Jeong-Yeon Ha, Yanbai Jin, Amy McWilliams, Theirry Panggabean, Zhengyu Peng, Jing Ru, Jiacheng She, Lujin Sun, Jialin Wang, Zilun Wei, Jiayuan Zhu
Applied Physics
Topology-guided vortices in a polariton condensate
Andrea Zacheo, Marco Marangi, Nilo Mata-Cervera et al. (+3 more)
A major challenge in polariton fluids is achieving deterministic control over the
spin texture of the macroscopic condensate wavefunction, which dictates the nucleation and dynamics of topological excitations, such as
vortices,
solitons, and strings. Existing approaches typically rely on external gauge fields to indirectly access the polariton pseudospin, resulting in configurations that are weakly constrained by the cavity modes and therefore highly sensitive to disorder and fluctuations. Here, we report the generation of
spin polaritons constrained to the
topology of a bound state in the continuum (BIC) metasurface with broken inversion
symmetry carved into a polycrystalline halide-perovskite film. Geometry-induced polariton condensation under
spin-momentum locking gives rise to a pair of half-
vortices of opposite
spin, intrinsically pinned to polarization strings, emerging as topological extensions of the
vortex cores. Consequently, varying the excitation density drives a controlled displacement of the half-
vortices along the trajectories imposed by the strings, hindering their mutual annihilation across an interposed topological domain wall. This approach establishes cavity geometry as an intrinsic source of
spin textures to guide
vortex displacement in driven
quantum fluids, opening a route toward the generation of robust topological excitations within structurally disordered materials.
Read the full abstract ▾
All authors Andrea Zacheo, Marco Marangi, Nilo Mata-Cervera, Yijie Shen, Giorgio Adamo, Cesare Soci
Applied Physics
Electrically Pumped Terahertz Frequency Comb Based on Actively Mode-locked Resonant Tunneling Diode
Feifan Han, Xiongbin Yu, Qun Zhang et al. (+6 more)
Terahertz (THz) frequency combs (TFCs) are promising for numerous applications in spectroscopy, metrology, sensing, and wireless communications. However, the practical applications of TFCs have been hindered thus far by the need for cryogenic cooling, limited bandwidth, and bulky configuration, largely due to the lack of advanced THz sources. Here, we report an electrically pumped, room-temperature, broadband, compact, and tunable TFC by integrating an actively mode-locked resonant tunneling diode (RTD) in a metallic waveguide. By injecting a strong, continuous-wave
radio frequency (RF) signal into a direct-current-driven RTD oscillator, we experimentally demonstrate a broadband, offset-free comb spectrum spanning more than one octave, from 0.14 to 0.325 THz at room temperature. Moreover, we show that the repetition frequency of the TFC can be tuned from 0.9 to 50 GHz by the injected RF signal, and a 120 Gbps (16 Gbps per channel) data rate can be achieved in the TFC-based high-speed single-channel (multi-channel) wireless communications.
Read the full abstract ▾
All authors Feifan Han, Xiongbin Yu, Qun Zhang, Zebin Huang, Longhao Zou, Weichao Li, Jingpu Duan, Zhen Gao, Xiaofeng Tao
Atomic Physics
Directional loss of contrast by dephasing in temporal double-slit interferometry
M. A. H. B. Md Yusoff, H. B. Ambalampitiya and J. M. Ngoko Djiokap
Attosecond streaking camera is an ex situ technique in which a linearly polarized (LP) XUV attopulse produces an electron wavepacket by photoionization in the presence of an IR femtopulse. By moving the two synchronous oppositely circularly polarized XUV pulses (that make the ionizing LP pulse) apart in time, we propose an attosecond double-slit streak camera scheme to see information loss in polarization-dependent two-slit phenomena. Such streaking interferogram is then composed of several Feynman's thought experiments in time domain, in which electrons are affected by the IR pulse as they exit the two attoslits upon XUV ionization processes to form Archimedean spiral patterns. As a proof-of-principle, when the IR femtofield and first XUV attopulse are synchronous, a loss of contrast through dephasing is seen in the simulated momentum and energy distributions of the photoelectron. It is shown that the contrast between bright and dark interference fringes diminishes predominantly along the IR-field polarization axis and is sensitive to the IR-field waveform. Our which-time information scheme provides further confirmation of the wave-particle duality.
Read the full abstract ▾
Physics and Society
A Network Dynamical Systems Approach to SDGs
Wuyang Zhang and Lejun Xu
The United Nations' Sustainable Development Goals (SDGs) represent a complex, interdependent framework where progress in one area can synergistically promote or competitively inhibit progress in others. For policymakers in international development, a critical challenge is identifying "leverage points" - specific goals where limited resource allocation yields the maximum system-wide benefit. This study addresses this challenge by modeling the SDGs as a Networked Dynamical System (NDS). Using empirical data from Our World in Data (2018), we construct a weighted interaction network of 16 SDG indicators. We employ Principal Component Analysis (PCA) and multiple linear regression to derive coupling weights empirically. Unlike previous static analyses, we simulate the temporal
evolution of development indicators using an extended Lotka-Volterra model. To ensure numerical stability and sophistication, we upgrade the simulation method from standard Euler integration to the Runge-Kutta 4 (RK4) method. Our simulation, applied to a case study of Mexico, reveals that SDG 4 (Quality Education) acts as a critical driver, suggesting that prioritizing education yields the most significant positive spillover effects across the development network. Furthermore, we perform sensitivity analysis and explore the power-law relationship between investment and stability.
Read the full abstract ▾
Fluid Dynamics · Cross-listed from cond-mat.soft
Relation between extensional viscosity and polymer conformation in dilute polymer solutions
Yusuke Koide, Takato Ishida, Takashi Uneyama et al. (+1 more)
We investigate extensional viscosity and
polymer conformation in dilute
polymer solutions under uniaxial extensional flow using dissipative particle dynamics simulations. At high extension rates,
polymers are significantly stretched by extensional flows, and the extensional viscosity growth function exhibits strain hardening. To reveal their quantitative relation, we adopt an analysis method based on the Rouse-type model. We demonstrate that the extensional viscosity growth function is determined by the instantaneous gyration radii in the parallel and perpendicular directions to the extensional direction and their time derivatives. Our approach also provides a unified description of the steady-state extensional viscosity of dilute
polymer solutions for various chain lengths and concentrations in terms of the
polymer gyration radius.
Read the full abstract ▾
All authors Yusuke Koide, Takato Ishida, Takashi Uneyama, Yuichi Masubuchi
Optics
Wavefront Reconstruction for Fractional Lateral Shear Measurements using Weighted Integer Shear Averages
Samia Heshmat, Satoshi Tomioka, Naoki Miyamoto et al. (+3 more)
Wavefront reconstruction in lateral shearing interferometry typically assumes that the shear amount is an integer multiple of the sampling interval. When the shear is fractional, approximating it with the nearest integer value leads to noticeable reconstruction errors. To address this, we propose a weighted integer shear averaging method. The approach combines reconstructions from nearby integer shears with carefully chosen weights designed to cancel the dominant error terms. Analytical error analysis shows that two-shear averaging removes first-order errors, while three-shear averaging removes second-order errors. Numerical simulations with a test wavefront confirm that the method achieves significantly lower RMS error than conventional single-shear reconstruction. The technique is simple, computationally efficient, and can be readily extended to two-dimensional interferometry. This makes weighted integer shear averaging a practical and accurate tool for wavefront reconstruction when fractional shear is unavoidable.
Read the full abstract ▾
All authors Samia Heshmat, Satoshi Tomioka, Naoki Miyamoto, Yuji Yamauchi, Yutaka Matsumoto, Naoki Higashi
Optics
A universal framework for nonlinear frequency combs under electro-optic modulation
Yanyun Xue, Xianpeng Lv, Guangxing Wu et al. (+9 more)
Nonlinear frequency combs, including electro-optic and Kerr combs, have become central platforms for chip-scale frequency synthesis. Recent breakthroughs in strong-coupling electro-optic modulation further expanded their accessible nonlinear dynamics, unlocking new phenomena and functionalities, but the underlying foundation remains largely unexplored. Here we establish a universal theoretical and experimental framework for nonlinear combs under arbitrary electro-optic modulation by introducing a general
evolution equation (GEE) that transcends the mean-field Lugiato-Lefever equation. The GEE reduces to a discrete-time Integration
Hamiltonian that provides a frequency-domain formalism unifying strong-coupling electro-optic modulation with photonic synthetic dimensions. Together with a band-wave correspondence linking modulation waveforms to synthetic band structures, the formalism enables programmable spectral control. We further show compatibility between Kerr nonlinearity and strong-coupling electro-optic modulation, highlighting their cooperative dynamics. Our work provides a foundational model for strong-coupling electro-optics in nonlinear combs, opening a route toward chip-integrated, microwave-programmable comb sources for metrology, spectroscopy, and emerging photonic technologies.
Read the full abstract ▾
All authors Yanyun Xue, Xianpeng Lv, Guangxing Wu, Tianqi Lei, Chenyang Cao, Yiming Lei, Min Wang, Zhendong Zhu, Yan Li, Qihuang Gong, Di Zhu, Yaowen Hu
Fluid Dynamics
Hardware-Accelerated Phase-Averaging for Cavitating Bubbly Flows
Diego Vaca-Revelo, Benjamin Wilfong, Spencer H. Bryngelson et al. (+1 more)
We present a comprehensive validation, performance characterization, and scalability analysis of a hardware-accelerated phase-averaged multiscale solver designed to simulate acoustically driven dilute bubbly suspensions. The carrier fluid is modeled using the compressible Navier-Stokes equations. The dispersed phase is represented through two distinct subgrid formulations: a volume-averaged model that explicitly treats discrete bubbles within a Lagrangian framework, and an ensemble-averaged model that statistically represents the bubble population through a discretized distribution of bubble sizes. For both models, the bubble dynamics are modeled via the Keller–Miksis equation. For the GPU cases, we use OpenACC directives to offload computation to the GPUs. The volume-averaged model is validated against the analytical Keller-Miksis solution and experimental measurements, showing excellent agreement with root-mean-squared errors of less than 8% for both single-bubble oscillation and collapse scenarios. The ensemble-averaged model is validated by comparing it to volume-averaged simulations. On an NCSA Delta node with 4 NVIDIA A100 GPUs, we observe a speedup 16-fold compared to a 64-core AMD Milan CPU. The ensemble-averaged model offers additional reductions in computational cost by solving a single set of averaged equations, rather than multiple
stochastic realizations. However, the volume-averaged model enables the interrogation of individual bubble dynamics, rather than the averaged statistics of the bubble dynamics. Weak and strong scaling tests demonstrate good scalability across both CPU and GPU platforms. These results show the proposed method is robust, accurate, and efficient for the multiscale simulation of acoustically driven dilute bubbly flows.
Read the full abstract ▾
All authors Diego Vaca-Revelo, Benjamin Wilfong, Spencer H. Bryngelson, Aswin Gnanaskandan
Optics
Accelerated Coupled Mode Model for Fiber Laser Amplifiers as an Averaged Dynamical System
Rebecca Bryant, Jacob Grosek and Jay Gopalakrishnan
We apply a known
theorem for simplifying dynamical systems with bounded error to a specific optical fiber waveguide problem, supplementing the physical intuition and heuristics used in the optics community with proper mathematical justification. Using techniques from averaging theory of dynamical systems, a reliable accelerated model based on the coupled mode theory (CMT) approach for a common fiber
laser amplifier application is derived. Computational testing reveals that this accelerated model achieves an ${\sim}4000$x increase in computational speed compared to the CMT model while preserving a high accuracy in key figures-of-merit such as output power and amplification efficiency. Further, we argue that by adopting our recommended approximations within the reduced model framework enables the model to be applied a wider set of amplifier types and configurations than can the current (comparable) reduced models found in the literature.
Read the full abstract ▾
Instrumentation and Detectors
A Hands-On Workshop for Constructing a Low-Field MRI System in Three Days
Ivan Etoku Oiye, Ajay Sharma, Zinia Mohanta et al. (+20 more)
Access to
Magnetic Resonance Imaging system assembly knowledge can be expanded by leveraging open-source hardware and software, simplified installation requirements, and collaborative training initiatives. To this end, we conducted a three-day workshop to construct an operational 0.27T MRI scanner. The workshop hosted 16 participants, including faculty, postdoctoral fellows, trainers, and students, who collaborated to build the scanner using open-source hardware and software components. Teams were designated to focus on various subsystems, including the magnet, passive shimming, radiofrequency (RF) coils, gradient coils, data acquisition, and reconstruction. Pre-workshop preparation involved simulation-based design processes and fabrication techniques, which incorporated configuring MaRCoS and PyPulseq libraries, CNC machining, and 3D printing. During the workshop, participants assembled an H-shaped magnet, which achieved a peak
magnetic field strength of 0.269T. Passive shimming effectively reduced the field inhomogeneity from 3mT to 2mT. A 3 cm diameter RF solenoid was built and tuned to 11.4 MHz. The gradients exhibited less than 5% non-linearity in simulations and were fabricated by CNC machining copper plates. The assembled system was used to acquire a 2D
spin echo of a water phantom. Following the workshop, the system was further optimized to scan relaxometry phantoms. A post-workshop survey was carried out, revealing over 87% satisfaction. The constructed scanner represents a valuable platform for educational initiatives, pulse sequence development, and preclinical research imaging efforts.
Read the full abstract ▾
All authors Ivan Etoku Oiye, Ajay Sharma, Zinia Mohanta, Dinil Sasi Sankaralayam, Yuto Uchida, Teni Akinwale, Kexin Wang, Zechen Xu, Yifan Shuai, Vu Dinh, Sun Yuanqi, Aruna Singh, Dillip K. Senapati, Luke Ikard, Sandeep K. Ganji, Joseph Reilly, Michael Mcmahon, Hanzhang Lu, Peter Barker, Jennifer Morrison, Steven M. Ross, Zaver Bhujwalla, Sairam Geethanath
Physics and Society
AI4X Roadmap: Artificial Intelligence for the advancement of scientific pursuit and its future directions
Stephen G. Dale, Nikita Kazeev, Alastair J. A. Price et al. (+65 more)
Artificial intelligence and machine learning are reshaping how we approach scientific discovery, not by replacing established methods but by extending what researchers can probe, predict, and design. In this roadmap we provide a forward-looking view of AI-enabled science across biology, chemistry,
climate science, mathematics, materials science, physics, self-driving laboratories and unconventional computing. Several shared themes emerge: the need for diverse and trustworthy data, transferable electronic-structure and interatomic models, AI systems integrated into end-to-end scientific workflows that connect simulations to experiments and generative systems grounded in synthesisability rather than purely idealised phases. Across domains, we highlight how large foundation models, active learning and self-driving laboratories can close loops between prediction and validation while maintaining reproducibility and physical interpretability. Taken together, these perspectives outline where AI-enabled science stands today, identify bottlenecks in data, methods and infrastructure, and chart concrete directions for building AI systems that are not only more powerful but also more transparent and capable of accelerating discovery in complex real-world environments.
Read the full abstract ▾
All authors Stephen G. Dale, Nikita Kazeev, Alastair J. A. Price, Victor Posligua, Stephan Roche, O. Anatole von Lilienfeld, Konstantin S. Novoselov, Xavier Bresson, Gianmarco Mengaldo, Xudong Chen, Terence J. O'Kane, Emily R. Lines, Matthew J. Allen, Amandine E. Debus, Clayton Miller, Jiayu Zhou, Hiroko H. Dodge, David Rousseau, Andrey Ustyuzhanin, Ziyun Yan, Mario Lanza, Fabio Sciarrino, Ryo Yoshida, Zhidong Leong, Teck Leong Tan, Qianxiao Li, Adil Kabylda, Igor Poltavsky, Alexandre Tkatchenko, Sherif Abdulkader Tawfik, Prathami Divakar Kamath, Theo Jaffrelot Inizan, Kristin A. Persson, Bryant Y. Li, Vir Karan, Chenru Duan, Haojun Jia, Qiyuan Zhao, Hiroyuki Hayashi, Atsuto Seko, Isao Tanaka, Omar M. Yaghi, Tim Gould, Bun Chan, Stefan Vuckovic, Tianbo Li, Min Lin, Zehcen Tang, Yang Li, Yong Xu, Amrita Joshi, Xiaonan Wang, Leonard W.T. Ng, Sergei V. Kalinin, Mahshid Ahmadi, Jiyizhe Zhang, Shuyuan Zhang, Alexei Lapkin, Ming Xiao, Zhe Wu, Kedar Hippalgaonkar, Limsoon Wong, Lorenzo Bastonero, Nicola Marzari, Dorye Luis Esteras Cordoba, Andrei Tomut, Alba Quinones Andrade, Jose-Hugo Garcia
Atmospheric and Oceanic Physics
Crowdsourcing the Frontier: Advancing Hybrid Physics-ML Climate Simulation via a $50,000 Kaggle Competition
Jerry Lin, Zeyuan Hu, Tom Beucler et al. (+24 more)
Subgrid machine-learning (ML) parameterizations have the potential to introduce a new generation of
climate models that incorporate the effects of higher-resolution physics without incurring the prohibitive computational cost associated with more explicit physics-based simulations. However, important issues, ranging from online instability to inconsistent online performance, have limited their operational use for long-term
climate projections. To more rapidly drive progress in solving these issues, domain scientists and machine learning researchers opened up the offline aspect of this problem to the broader machine learning and data science community with the release of ClimSim, a NeurIPS
Datasets and
Benchmarks publication, and an associated Kaggle competition. This paper reports on the downstream results of the Kaggle competition by coupling emulators inspired by the winning teams' architectures to an interactive
climate model (including full cloud microphysics, a regime historically prone to online instability) and systematically evaluating their online performance. Our results demonstrate that online stability in the low-resolution, real-geography setting is reproducible across multiple diverse architectures, which we consider a key milestone. All tested architectures exhibit strikingly similar offline and online biases, though their responses to architecture-agnostic design choices (e.g., expanding the list of input variables) can differ significantly. Multiple Kaggle-inspired architectures achieve state-of-the-art (SOTA) results on certain metrics such as zonal mean bias patterns and global RMSE, indicating that crowdsourcing the essence of the offline problem is one path to improving online performance in hybrid physics-AI
climate simulation.
Read the full abstract ▾
All authors Jerry Lin, Zeyuan Hu, Tom Beucler, Katherine Frields, Hannah Christensen, Walter Hannah, Helge Heuer, Peter Ukkonnen, Laura A. Mansfield, Tian Zheng, Liran Peng, Ritwik Gupta, Pierre Gentine, Yusef Al-Naher, Mingjiang Duan, Kyo Hattori, Weiliang Ji, Chunhan Li, Kippei Matsuda, Naoki Murakami, Shlomo Ron, Marec Serlin, Hongjian Song, Yuma Tanabe, Daisuke Yamamoto, Jianyao Zhou, Mike Pritchard
Plasma Physics
Isotope Production in Muon-Catalyzed-Fusion Systems
J. F. Parisi and A. Rutkowski
Producing valuable isotopes with high-flux high-energy
neutrons generated by
muon-catalyzed fusion ($\mu$CF) reactions could substantially improve the economic prospects for
muon-catalyzed fusion. Because no external heating is required for $\mu$CF, heat flux constraints are significantly relaxed compared with fusion systems requiring external heating. This could allow $\mu$CF to attain much higher
neutron flux without breaching material heat flux limits. If
muon production rates can be increased, $\mu$CF systems employing transmutation could be viable well before energy breakeven is possible. For $\mu$CF systems transmuting valuable isotopes, the required number of catalyzed fusion events per
muon and
muon energy generation cost can be relaxed by several orders of magnitude relative to electricity-generating systems, making $\mu$CF an attractive high-flux
neutron source. We show an example $\mu$CF system with a 10 gram ${}^{226}\mathrm{Ra}$ feedstock and a steady-state
muon rate of $10^{12}$
muons / second - roughly half a kilowatt of fusion power - could produce 20 mg of ${}^{225}\mathrm{Ac}$ per year - comparable to 400 times global supply in 2024. As higher
muon rate sources become available, many other radioisotope transmutation pathways become viable. These findings motivate the accelerated development of $\mu$CF systems for
neutron-driven isotope production far before net energy generation is possible.
Read the full abstract ▾