Showing 1–50 of 112 results for author: Peng, Z

PocketCaBER and PocketDoS: Low-cost open-source tools for teaching and learning advanced topics in fluid mechanics

Authors: Zhaofeng Peng, Lucas Warwaruk, Thomas Livesay, Benjamin M. Yavitt, Randy H. Ewoldt, Gareth H. McKinley, Laurel Kroo

Abstract: We describe two open-source, 3D-printable, flexure-based tools for the quantitative measurement of extensional properties of viscoelastic fluids. These low-cost, portable, and scalable devices (which we have termed ``PocketCaBER'' and ``PocketDoS'') are particularly applicable for use in the field and in graduate-level teaching environments due to their low cost, printability on hobby 3D printers,… ▽ More We describe two open-source, 3D-printable, flexure-based tools for the quantitative measurement of extensional properties of viscoelastic fluids. These low-cost, portable, and scalable devices (which we have termed ``PocketCaBER'' and ``PocketDoS'') are particularly applicable for use in the field and in graduate-level teaching environments due to their low cost, printability on hobby 3D printers, compatibility with cell phone cameras, portability and user-friendly operation. We characterize and benchmark each device's performance against its lab-equivalent counterpart and provide downloadable STL files for rapid fabrication. We discuss experimental limitations of these devices compared with their bench-top counterparts. Finally, we illustrate the use of such tools in facilitating student engagement in polymer science and complex fluids classes---specifically, how progress in learning goals can be uniquely and effectively accelerated by providing the necessary rheological instruments directly to each individual student (especially for advanced modules such as nonlinear extensional rheology). By giving students personal, indefinite access to laboratory-level instrumentation through these open-source frugal science tools, we discuss our efforts to expand participation and engagement within the field of nonlinear rheology. △ Less

Submitted 12 August, 2026; originally announced August 2026.

AlgoPlasma: Open Algorithms for Plasma Modeling

Authors: Yinjian Zhao, Zhongping Zhao, Zhe Liu, Baisheng Wang, Zilong Peng, Xin Luo, Lihuan Xie, Xi Chen, Zhijun Zhou, Kunpeng Zhong, Yingjie Chen, Changzheng Hu

Abstract: AlgoPlasma is an open-source library in which core numerical algorithms for plasma modeling are implemented as modular, well-documented, and independently testable components. Rather than offering a complete simulation code, it allows researchers to select, adapt, and assemble the required components into application-specific workflows. The current release is centered on particle-based simulation,… ▽ More AlgoPlasma is an open-source library in which core numerical algorithms for plasma modeling are implemented as modular, well-documented, and independently testable components. Rather than offering a complete simulation code, it allows researchers to select, adapt, and assemble the required components into application-specific workflows. The current release is centered on particle-based simulation, while AlgoPlasma is designed to encompass a broader range of approaches to plasma modeling. It provides components for particle initialization and advancement, particle--grid coupling, field solution, collision modeling, parallel data exchange, input/output, and selected fluid updates. Documentation links mathematical formulations to source implementations, interfaces, and usage, while verification and validation cases evaluate numerical accuracy and physical behavior. AlgoPlasma thus establishes a shared algorithmic foundation for plasma modeling, transforming repeatedly reimplemented numerical methods into open, reusable, tested, and explainable components for research, verification, education, and collaborative development. △ Less

Submitted 15 August, 2026; originally announced August 2026.

All-optical switching of nonlinear structured light in crystal-engineered van der Waals materials

Authors: Paolo Valisa, Marc Richstaetter, Bianca Sanfilippo, Benedikt Ursprung, Zhi Hao Peng, Victoria Quiros-Cordero, Francesco Gucci, Xiaoyang Zhu, P. James Schuck, Giulio Cerullo, Luca Carletti, Chiara Trovatello

Abstract: The orbital angular momentum (OAM) of light is a discrete, unbounded degree of freedom that underpins mode-multiplexed communications and high-dimensional quantum photonics. Yet, dynamic OAM control remains dependent on bulky free-space optics or cascaded architectures that separate switching from wavefront shaping, hindering nanoscale integration. Here, we engineer artificial van der Waals crysta… ▽ More The orbital angular momentum (OAM) of light is a discrete, unbounded degree of freedom that underpins mode-multiplexed communications and high-dimensional quantum photonics. Yet, dynamic OAM control remains dependent on bulky free-space optics or cascaded architectures that separate switching from wavefront shaping, hindering nanoscale integration. Here, we engineer artificial van der Waals crystals from rhombohedrally stacked (3R) MoS$_2$, in which spatial control of the local crystal orientation imprints a nonlinear geometric phase onto the second-harmonic (SH) field, enabling background-free generation of SH vortex beams in an ultrathin (46 nm) van der Waals platform. Leveraging the C$_{3v}$ symmetry of 3R-MoS$_2$, we demonstrate monolithic, all-optical switching with sub-optical-cycle precision between Hermite-Gauss-like and Laguerre-Gaussian vortex SH beams with opposite topological charges ($l=\pm1$). Our results establish artificial 3R-MoS$_2$ crystals as a monolithic platform for the generation and all-optical reconfiguration of nonlinear structured light at the nanoscale, advancing active nanophotonic sources for integrated classical and quantum photonic technologies. △ Less

Submitted 13 August, 2026; originally announced August 2026.

Final assessment of radioactive impurities in the JUNO detector

Authors: Thomas Adam, Fengpeng An, Costas Andreopoulos, Giuseppe Andronico, Nikolay Anfimov, Vito Antonelli, Tatiana Antoshkina, João Pedro Athayde Marcondes de André, Didier Auguste, Nikita Balashov, Andrea Barresi, Davide Basilico, Eric Baussan, Marco Beretta, Antonio Bergnoli, Nikita Bessonov, Daniel Bick, Lukas Bieger, Svetlana Biktemerova, Thilo Birkenfeld, Simon Blyth, Manuel Böhles, Anastasia Bolshakova, Mathieu Bongrand, Matteo Borghesi , et al. (549 additional authors not shown)

Abstract: The Jiangmen Underground Neutrino Observatory (JUNO) collaboration has completed the construction of the 20,000-ton liquid scintillator detector and the associated muon veto detector system. To meet the physics objectives, the materials used in the detector must exhibit low radioactive contamination. The single-event rate in the fiducial volume (R $<$ 17.2 m) of the scintillator is required to be… ▽ More The Jiangmen Underground Neutrino Observatory (JUNO) collaboration has completed the construction of the 20,000-ton liquid scintillator detector and the associated muon veto detector system. To meet the physics objectives, the materials used in the detector must exhibit low radioactive contamination. The single-event rate in the fiducial volume (R $<$ 17.2 m) of the scintillator is required to be approximately 7 Hz for energies above 0.7 MeV, resulting in an accidental coincidence background of about 1 event per day for reactor neutrino physics analyses. Since the beginning of the construction phase, we have screened the natural radioactivity content of thousands of materials, to select those that meet the design background budget. The radioactive impurity concentrations of the materials ultimately used in the JUNO detector are summarized in this paper. The construction of the entire detector and the subsequent filling of the liquid scintillator were completed in August 2025. From the initial data, the total count rate of natural radioactivity within the detector's fiducial volume has met the requirements and is sufficient to support the reactor antineutrino analysis. △ Less

Submitted 19 July, 2026; originally announced July 2026.

Impact of Residual Angular Chirp in a Petawatt-class Laser System on Laser-driven Proton Acceleration

Authors: Qingfan Wu, Minjian Wu, Jiarui Zhao, Ying Gao, Haoran Chen, Tan Song, Zhongshuai Zhang, Zhangyi Wu, Tianhao Liang, Shirui Xu, Ziyang Peng, Hui Zhang, Tianqi Xu, Qihang Han, Chenghao Hua, Ke Chen, Pengcheng Fan, Yuntian Xie, Xianduo Li, Peiqiang Liu, Xiangyu Nong, Shengxuan Xu, Liyong Ma, Yixing Geng, Chen Lin , et al. (3 additional authors not shown)

Abstract: Laser-driven proton acceleration has attracted considerable interest owing to its appealing potential in versatile applications including cancer therapy. Proton energies depend critically on the on-target intensities, yet the detrimental impact of focal spot degradation induced by spatiotemporal couplings on the acceleration remains insufficiently elucidated. In this study, we demonstrate that res… ▽ More Laser-driven proton acceleration has attracted considerable interest owing to its appealing potential in versatile applications including cancer therapy. Proton energies depend critically on the on-target intensities, yet the detrimental impact of focal spot degradation induced by spatiotemporal couplings on the acceleration remains insufficiently elucidated. In this study, we demonstrate that residual angular chirp (AC), stemming from minor misalignments of the grating compressor in a Petawatt-class laser system, acts as a critical bottleneck for proton acceleration. Experimental results reveal that even around 100 microradians of grating misalignment induces substantial focal-spot elongation and a pronounced reduction in peak intensity. By implementing an in situ spectral-blocking diagnostic, we effectively eliminated the residual AC and restored a near-diffraction-limited focus. This optimization led to a significant recovery of the on-target intensity, resulting in a twofold increase in the proton cutoff energy. Our work presents a successful demonstration of diagnosing and eliminating residual AC. This provides a practical reference for generating high-energy proton beams and supporting their diverse applications in a PW-class laser. △ Less

Submitted 14 July, 2026; originally announced July 2026.

Comments: Accepted by Matter and Radiation at Extremes (MRE)

Droplet Fusion as a Relaxation Process: Comparison with Shape Recovery of Newtonian and Viscoelastic Droplets

Authors: Mohammad Moein Naderi, Zhangli Peng, Huan-Xiang Zhou

Abstract: Biomolecular condensates formed by phase separation often exhibit viscoelastic behavior, yet their shape recovery and fusion dynamics are frequently interpreted using purely viscous models. Here, we develop a unified theoretical and computational framework to quantify how viscoelasticity governs these two processes. We combine analytical theory for small-deformation shape recovery with axisymmetri… ▽ More Biomolecular condensates formed by phase separation often exhibit viscoelastic behavior, yet their shape recovery and fusion dynamics are frequently interpreted using purely viscous models. Here, we develop a unified theoretical and computational framework to quantify how viscoelasticity governs these two processes. We combine analytical theory for small-deformation shape recovery with axisymmetric finite-element simulations based on the Oldroyd-B constitutive model to systematically investigate both shape recovery and droplet fusion under comparable conditions. Our results show that, although both processes are driven by capillary forces, they are fundamentally distinct in their underlying physics. Shape recovery is governed by global viscocapillary relaxation of a single connected interface and follows single- or multi-exponential decay depending on the relative magnitude of the viscocapillary timescale and the stress relaxation time. In contrast, droplet fusion is intrinsically a multistage process involving localized curvature-driven neck formation, rapid bridge expansion, and a transition to global relaxation. We demonstrate that viscoelasticity introduces an additional intrinsic timescale that governs the competition between capillary driving and stress relaxation, characterized by the Deborah number. This leads to enhanced intermediate-stage fusion dynamics and modified relaxation behavior compared to Newtonian droplets. Furthermore, we show that the presence of an exterior fluid introduces additional hydrodynamic dissipation, significantly slowing the fusion process. Finally, we compare the computationally predicted droplet fusion in the Newtonian and viscoelastic cases with a stretched-exponential empirical formula. Deviations observed in viscoelastic regimes highlight the limitations of purely viscous descriptions and the need for models incorporating stress relaxation. △ Less

Submitted 24 June, 2026; originally announced June 2026.

Comments: 16 pages, 10 figures

Accurate identification and measurement of the precipitate area by two-stage deep neural networks in novel chromium-based alloys

Authors: Zeyu Xia, Kan Ma, Sibo Cheng, Thomas Blackburn, Ziling Peng, Kewei Zhu, Weihang Zhang, Dunhui Xiao, Alexander J Knowles, Rossella Arcucci

Abstract: The performance of advanced materials for extreme environments is underpinned by their microstructure, including the size and distribution of reinforcing phases. Chromium-based superalloys are a recently proposed alternative to conventional face-centred-cubic superalloys for high-temperature applications, such as Concentrated Solar Power, and their development requires efficient measurement of pre… ▽ More The performance of advanced materials for extreme environments is underpinned by their microstructure, including the size and distribution of reinforcing phases. Chromium-based superalloys are a recently proposed alternative to conventional face-centred-cubic superalloys for high-temperature applications, such as Concentrated Solar Power, and their development requires efficient measurement of precipitate volume fraction and size distribution from electron microscopy images. Traditional fixed-threshold image processing is sensitive to background noise, generalises poorly across materials, and requires substantial manual measurement effort. To address these bottlenecks, this study proposes DT-SegNet, an end-to-end two-stage deep learning scheme based on YOLOv5 and SegFormer for object detection and segmentation in electron microscopy images. The approach combines the training efficiency of convolutional neural networks at the detection stage with the segmentation accuracy of a Vision Transformer. Numerical experiments show that DT-SegNet substantially outperforms state-of-the-art segmentation tools offered by Weka and ilastik across metrics including accuracy, precision, recall, and F1-score. The model provides a useful tool for alloy-development microstructure examinations and helps address the large datasets associated with high-throughput alloy development. △ Less

Submitted 20 June, 2026; originally announced June 2026.

Comments: 18 pages, 11 figures. Published in Phys. Chem. Chem. Phys

Journal ref: Phys. Chem. Chem. Phys. 25, 15970-15987 (2023)

Test of the JUNO 20-inch PMTs during Installation

Authors: Haojie Dong, Zhaoyuan Peng, Zhonghua Qin, Wan Xie, Haoqi Lu, Jun Hu, Lei Fan, Xiaoshan Jiang, Chao Chen, Xiaolu Ji, Fei Li, Shenghui Liu, Xiaochuan Xie, Mei Ye, Hongzhao Yu, Zeyuan Yu

Abstract: Photomultiplier tubes (PMTs) are widely used in neutrino experiments. As a new-generation neutrino observatory, JUNO requires an excellent energy resolution of 3% at 1 MeV. This will be realized with a 20 kton liquid scintillator detector instrumented with more than 20000 20-inch PMTs and 25600 3-inch PMTs. These PMTs were successfully installed in JUNO from October 2022 to December 2024. During t… ▽ More Photomultiplier tubes (PMTs) are widely used in neutrino experiments. As a new-generation neutrino observatory, JUNO requires an excellent energy resolution of 3% at 1 MeV. This will be realized with a 20 kton liquid scintillator detector instrumented with more than 20000 20-inch PMTs and 25600 3-inch PMTs. These PMTs were successfully installed in JUNO from October 2022 to December 2024. During the installation, seven test campaigns were performed to validate the PMT functionality, including measurements dark count rate, gain, waveform, and charge spectrum. In this paper, we present the implementation of these tests and the corresponding results for the 20-inch PMTs throughout the installation process. △ Less

Submitted 19 June, 2026; originally announced June 2026.

Comments: 14 pages, 16 figures, accepted by Radiation Detection Technology and Methods

Plateau Gaps of Poisson Correctors Encode Metastable Reaction Rates

Authors: Sang Yang, Zhixin Peng

Abstract: Metastable reaction rates are commonly inferred from transition-state fluxes, mean first-passage times, or fitted kinetic models. We show that they are directly encoded in the plateau gap of an occupation-time Poisson corrector. For a centered basin-occupation observable, the Poisson corrector develops metastable plateaus in the reactant and product basins, and their separation determines the forw… ▽ More Metastable reaction rates are commonly inferred from transition-state fluxes, mean first-passage times, or fitted kinetic models. We show that they are directly encoded in the plateau gap of an occupation-time Poisson corrector. For a centered basin-occupation observable, the Poisson corrector develops metastable plateaus in the reactant and product basins, and their separation determines the forward and backward transition rates. This construction requires only the generator, stationary measure, and metastable partition, and therefore does not rely on a predefined transition-state surface. In overdamped and underdamped double-well dynamics, the plateau-gap rate recovers the Kramers, Grote-Hynes, and Pollak-Grabert-Hänggi hierarchy. The same corrector-martingale decomposition yields a reactive-noise density, revealing where stochastic forcing contributes to transitions in configuration or phase space. Thus, reaction rates and their fluctuation sources emerge from a single corrector field. △ Less

Submitted 10 June, 2026; originally announced June 2026.

Comments: 11pages, 5figures

Scaling native entanglement generation in layered semiconductors with quasi-phase matching

Authors: Benjamin Braun, Andrea Alessandrini, Josip Bajo, Philipp K. Jenke, Leone di Mauro Villari, Birui Yang, Zhi Hao Peng, P. James Schuck, Cory R. Dean, Andrea Marini, Philip Walther, Chiara Trovatello, Lee A. Rozema

Abstract: Efficient generation of entangled photons typically relies on spontaneous parametric down-conversion (SPDC) in phase-matched macroscopic nonlinear media. However, generating entanglement under phase-matching constraints requires additional bulk optics or interferometers. In contrast, ultrathin van der Waals semiconductors - such as transition metal dichalcogenides (TMDs) - exhibit strong enough op… ▽ More Efficient generation of entangled photons typically relies on spontaneous parametric down-conversion (SPDC) in phase-matched macroscopic nonlinear media. However, generating entanglement under phase-matching constraints requires additional bulk optics or interferometers. In contrast, ultrathin van der Waals semiconductors - such as transition metal dichalcogenides (TMDs) - exhibit strong enough optical nonlinearities for SPDC to be observed from subwavelength-thick media, thereby bypassing conventional phase-matching constraints. In this microscopic domain, the intrinsic crystal symmetry governs the nonlinear optical response, enabling the native generation of polarization-entangled photon pairs. However, generating these states efficiently has been fundamentally restricted by the material's coherence length ($L_c$), which limits the attainable conversion efficiency. Here, we investigate periodically-poled TMDs (PPTMDs) designed to scale up this interaction via quasi-phase matching. We demonstrate that mechanically flipping the sign of the nonlinearity at precise intervals of $L_c$ introduces quasi-phase matching, that scales the pair-production rate while preserving the pristine, symmetry-generated polarization entanglement, with fidelities exceeding 99%. Backed by a rigorous theoretical model, our work clarifies the interplay between crystal symmetry and propagation effects in thin nonlinear media, providing a new avenue for engineering quantum light in nanophotonic systems. △ Less

Submitted 12 June, 2026; originally announced June 2026.

Comments: 7 pages, 3 figures, and an Appendix

Likelihood topology and applicability limits of spatial anti-aliasing inversion for folded electron drift instability dispersion in Hall thrusters

Authors: Zilong Peng, Baisheng Wang, Zhongping Zhao, Daren Yu, Yinjian Zhao

Abstract: The electron drift instability (EDI) is widely recognized as the leading mechanism for anomalous electron transport in Hall thrusters, but its millimeter and sub-millimeter wavelength makes conventional wave-probe analysis strongly limited by spatial aliasing. A multi-geometry spatial anti-aliasing algorithm provides a route for wave-probe diagnostics to break the spatial Nyquist limit, but its ef… ▽ More The electron drift instability (EDI) is widely recognized as the leading mechanism for anomalous electron transport in Hall thrusters, but its millimeter and sub-millimeter wavelength makes conventional wave-probe analysis strongly limited by spatial aliasing. A multi-geometry spatial anti-aliasing algorithm provides a route for wave-probe diagnostics to break the spatial Nyquist limit, but its effectiveness for nonmonotonic, folded, multi-resonance EDI dispersion has not been quantified. Using the numerically solved linear kinetic EDI dispersion relation under typical Hall-thruster discharge parameters as a benchmark, this work evaluates two-dimensional maximum-likelihood spatial anti-aliasing inversion based on two-probe synthetic signals generated for 25 simulated angle-spacing configurations. For a sampling frequency fs = 100 MHz and signal-to-noise ratio SNR = 10, the method breaks the conventional Nyquist wavenumber limit of about 1 krad/m, extends the accessible range to about 22 krad/m, and recovers the dominant likelihood ridges associated with the first- to fifth-order EDI branches. Parameter scans further show that the statistical realization count L mainly determines the suppression of spurious alias peaks, whereas the frequency resolution delta f mainly determines local branch separation near folded extrema. These results provide benchmark sampling and segmentation constraints for multi-geometry wave-probe diagnosis of EDI dispersion under the present synthetic conditions and can guide future experiments. △ Less

Submitted 2 June, 2026; originally announced June 2026.

Two-dimensional alternating ferrimagnetism with strain-controlled half-metallic state and valley polarization

Authors: W. Z. Zhuo, Z. H. Guan, Z. L. Peng, Y. N. Pan, J. Chen, Y. Yang, M. H. Qin

Abstract: The discovery of altermagnetism offers new opportunities for exploring novel quantum states and developing spintronic devices for enabling momentum dependent spin splitting in compensated systems, while zero net magnetization limit its manipulability using conventional magnetic method. Here, we propose 2D alternating ferrimagnetism,a phase merging alternating momentum dependent spin splitting with… ▽ More The discovery of altermagnetism offers new opportunities for exploring novel quantum states and developing spintronic devices for enabling momentum dependent spin splitting in compensated systems, while zero net magnetization limit its manipulability using conventional magnetic method. Here, we propose 2D alternating ferrimagnetism,a phase merging alternating momentum dependent spin splitting with a finite net magnetization. A tight binding model reveals that alternating ferrimagnetism originates from uncompensated magnetization in altermagnets, facilitating concurrent net magnetization and alternating spin splitting. First principles calculations and Monte Carlo simulations demonstrate stable alternating ferrimagnetism in strained and Cr substiting V2Te2O, which exhibit strain tunable net magnetization, reversable half metallicity and valley polarization, accompanied by long range magnetic order above room temperature. By combining altermagnetic and ferromagnetic properties, alternating ferrimagnetism expand the 2D magnetism landscape and offer pathways for energy efficient spintronic applications. △ Less

Submitted 21 May, 2026; originally announced May 2026.

AIMBio-Mat: An AI-Native FAIR Platform for Closed-Loop Materials Discovery and Biomedical Translation

Authors: D. -M. Mei, K. Acharya, C. M. Adhikari, M. Adhikari, S. Aryal, B. V. Benson, K. Bhatta, S. Bhattarai, N. Budhathoki, A. M. Castillo, D. Chakraborty, S. Chhetri, S. Choudhury, T. A. Chowdhury, R. D. Cruz, B. Cui, S. Dhital, K. -M. Dong, R. Gapuz, A. Ghasemi, E. Z. Gnimpieba, B. D. S. Gurung, H. A. Hashim, R. I. Harry, K. -E. Hasin , et al. (29 additional authors not shown)

Abstract: Materials discovery and biomedical translation increasingly require models that can reason across composition, processing, structure, biological response, manufacturability, safety, and governance constraints. Existing materials and biomedical data ecosystems are powerful but remain poorly coupled for AI-guided discovery. Here we present AIMBio, a conceptual framework for an AI-native, FAIR, and g… ▽ More Materials discovery and biomedical translation increasingly require models that can reason across composition, processing, structure, biological response, manufacturability, safety, and governance constraints. Existing materials and biomedical data ecosystems are powerful but remain poorly coupled for AI-guided discovery. Here we present AIMBio, a conceptual framework for an AI-native, FAIR, and governance-aware decision layer that links materials provenance, biomedical context, knowledge graphs, uncertainty-aware machine learning, and human-in-the-loop active learning. The framework formulates biomedical-materials discovery as constrained multi-objective optimization under uncertainty and introduces practical requirements for metadata, model documentation, risk-tiered governance, evaluation metrics, and phased implementation. To make the roadmap testable, we add a minimum viable prototype specification and a worked pilot for AI-guided nanomaterials for drug delivery. AIMBio is positioned as exploratory and preclinical discovery infrastructure, not as clinical decision-support software; any clinical or regulated-device use would require separate validation, change control, and regulatory review. The central contribution is a publishable platform blueprint for converting fragmented materials and biomedical records into auditable, experimentally actionable, and translationally responsible discovery workflows. △ Less

Submitted 20 May, 2026; originally announced May 2026.

Comments: 35 pages, 4 figures, and 12 tables

HotLoop Optimization of Petawatt Laser Focal Spot via a Twin-Focus Scheme

Authors: Qingfan Wu, Ying Gao, Minjian Wu, Jiarui Zhao, Shiyou Chen, Tianhao Liang, Haoran Chen, Tan Song, Zhongshuai Zhang, Zhangyi Wu, Shirui Xu, Ziyang Peng, Tianqi Xu, Zhuo Pan, Yujia Zhang, Qihang Han, Ke Chen, Chenghao Hua, Pengcheng Fan, Yuntian Xie, Yifei Shen, Shengxuan Xu, Liyong Ma, Yixing Geng, Chen Lin , et al. (3 additional authors not shown)

Abstract: Achieving diffraction-limited focusing of high-power laser pulses to generate ultra-high intensities is crucial for developing compact laser-driven particle accelerators and exploring strong-field quantum electrodynamics. However, accurately diagnosing and optimizing the focal spots of petawatt (PW) laser pulses remains a significant challenge. In this work, we present an experimental methodology… ▽ More Achieving diffraction-limited focusing of high-power laser pulses to generate ultra-high intensities is crucial for developing compact laser-driven particle accelerators and exploring strong-field quantum electrodynamics. However, accurately diagnosing and optimizing the focal spots of petawatt (PW) laser pulses remains a significant challenge. In this work, we present an experimental methodology utilizing a twin-focus scheme to precisely characterize the intensity distribution and wavefront of focused PW femtosecond laser pulses, and employ it to elucidate their power-dependent evolution. Furthermore, we optimized the focal spots at full power via our in-situ wavefront correction method termed ``HotLoop', achieving a Strehl ratio of 0.80 for 1 PW laser pulses. Consequently, the cutoff proton energies in laser proton acceleration experiments were significantly enhanced. The success of this approach underscores the necessity of in-situ high-energy wavefront correction for ultra-high intensity laser-matter interactions. △ Less

Submitted 19 May, 2026; originally announced May 2026.

Comments: Accepted by Matter and Radiation at Extremes (MRE)

Building a Regional Data-Centric Materials Science Ecosystem for Processing-Rich Materials Innovation in the Great Plains

Authors: D. -M. Mei, K. Acharya, C. M. Adhikari, M. Adhikari, S. Aryal, B. V. Benson, K. Bhatta, S. Bhattarai, N. Budhathoki, A. M. Castillo, D. Chakraborty, S. Chhetri, S. Choudhury, T. A. Chowdhury, R. D. Cruz, B. Cui, S. Dhital, K. -M. Dong, R. Gapuz, A. Ghasemi, E. Z. Gnimpieba, B. D. S. Gurung, H. A. Hashim, R. I. Harry, K. -E. Hasin , et al. (30 additional authors not shown)

Abstract: Data-centric materials science is changing how materials are discovered, optimized, manufactured, and qualified, yet many deployment-limiting materials problems still depend on experimental, processing-rich, device-level, and field-relevant data that are difficult to capture in conventional materials databases. This perspective argues that the Great Plains and adjacent interior research corridor c… ▽ More Data-centric materials science is changing how materials are discovered, optimized, manufactured, and qualified, yet many deployment-limiting materials problems still depend on experimental, processing-rich, device-level, and field-relevant data that are difficult to capture in conventional materials databases. This perspective argues that the Great Plains and adjacent interior research corridor can make a distinctive national contribution by organizing distributed experimental assets into a trusted regional materials-data ecosystem. The proposed model emphasizes FAIR metadata, provenance, persistent sample identifiers, uncertainty-aware modeling, semi-closed-loop workflows, stackable workforce training, and tiered governance for academic, public, controlled-access, and industry-protected data. We identify five coupled barriers -- fragmented data, weak algorithm--laboratory translation, uneven access to cyberinfrastructure and technical staff, workforce gaps at the materials--data interface, and insufficient incentives for sharing and reuse -- and propose a staged roadmap for addressing them. A high-purity germanium pilot illustrates how regional strengths can be converted into reusable datasets, benchmark models, trained personnel, and decision-improving workflows. The broader message is that regional leadership in data-centric materials science will depend less on geographic concentration than on trustworthy data practices, interoperable infrastructure, cross-trained people, and application-driven materials challenges. △ Less

Submitted 19 May, 2026; originally announced May 2026.

Comments: 33 pages, 6 figures, and 8 tables

Embedded underwater front-end electronics for the 3-inch photomultipliers in the JUNO experiment

Authors: Cédric Cerna, Miao He, Xiaoshan Jiang, Juan Pedro Ochoa-Ricoux, Frédéric Perrot, Angel Abusleme, Thomas Adam, Fengpeng An, Costas Andreopoulos, Giuseppe Andronico, João Pedro Athayde Marcondes de André, Nikolay Anfimov, Vito Antonelli, Tatiana Antoshkina, Didier Auguste, Nikita Balashov, Andrea Barresi, Davide Basilico, Eric Baussan, Marco Beretta, Antonio Bergnoli, Nikita Bessonov, Daniel Bick, Lukas Bieger, Svetlana Biktemerova , et al. (576 additional authors not shown)

Abstract: The Jiangmen Underground Neutrino Observatory (JUNO) is a 20-kton liquid scintillator-based, low-radioactivity, multi-purpose neutrino detector located 693 meters (1800 m.w.e.) underground in the Guangdong province, China. To detect scintillation light produced in the target, the detector is equipped with 17,612 20-inch photomultipliers (PMTs), forming the Large PMT system (LPMT). In addition, 25,… ▽ More The Jiangmen Underground Neutrino Observatory (JUNO) is a 20-kton liquid scintillator-based, low-radioactivity, multi-purpose neutrino detector located 693 meters (1800 m.w.e.) underground in the Guangdong province, China. To detect scintillation light produced in the target, the detector is equipped with 17,612 20-inch photomultipliers (PMTs), forming the Large PMT system (LPMT). In addition, 25,600 3-inch photomultipliers (the Small Photomultiplier System or SPMT) are deployed in the gaps between the LPMTs. This paper presents the design and performance of the underwater front-end electronics developed for the SPMT system. It details the individual electronics boards and their key components, the inter-board interfaces, the system-level design, and the firmware architecture that supports data acquisition and control. It also outlines mechanical and thermal integration, board validation procedures, and system performance metrics. The readout chain includes digitization of 128 PMT channels per unit, synchronized time-stamping, charge measurement, event packaging, and bandwidth management. Comprehensive validation confirms the system's readiness to meet JUNO's stringent physics goals. The underwater electronics achieve noise levels as low as 0.04 photoelectrons with minimal crosstalk (below 0.4%) and a bandwidth of 57 MB/s, ensuring reliable single photo-electron detection and operation under high-rate conditions. The SPMT system has now been fully integrated and installed in JUNO. Its commissioning and physics performance will be reported in a future publication. △ Less

Submitted 1 June, 2026; v1 submitted 28 April, 2026; originally announced April 2026.

Comments: Submitted to Nucl. Instrum. Methods Phys. Res. A

A Spatial-Resolved Proton Energy Spectrometer Based on a Scintillation-Fiber Cube

Authors: Tan Song, Ying Gao, Di Wang, Yujia Zhang, Jiarui Zhao, Qingfan Wu, Zhuo Pan, Shirui Xu, Ziyang Peng, Yulan Liang, Tianqi Xu, Zihao Zhang, Haoran Chen, Qihang Han, Xuan Liu, Ye Yang, Maocheng Wang, Siguang Wang, Yihua Yan, Zhongming Wang, Wenjun Ma

Abstract: Advanced particle acceleration methods have produced high-peak-current ion beams with broad energy spread and complex spatial distribution. There is an urgent need to develop online spatial-resolved energy spectrometers for high-energy pulsed ions. This paper introduces a novel spectrometer based on a scintillation-fiber cube for online diagnosis of proton beams with broadband energy spread and co… ▽ More Advanced particle acceleration methods have produced high-peak-current ion beams with broad energy spread and complex spatial distribution. There is an urgent need to develop online spatial-resolved energy spectrometers for high-energy pulsed ions. This paper introduces a novel spectrometer based on a scintillation-fiber cube for online diagnosis of proton beams with broadband energy spread and complex spatial distribution. We present its working principles, experimental setup, and comprehensive calibration using monoenergetic and spatially uniform proton beams generated by a synchrotron accelerator. Calibration results confirm an energy measurement range of 6-93 MeV, a relative energy uncertainty of 0.6% at 80 MeV, and a pixel size of 0.5 mm for beam profile reconstruction. By exploiting a custom-designed energy degrader, we generated a complex proton beam and measured it with the scintillation-fiber cube spectrometer (SFICS). The results demonstrate the spectrometer's potential for online measurement of the energy spectrum and spatial distribution of complex proton beams. △ Less

Submitted 22 April, 2026; originally announced April 2026.

Comments: 21 pages, 12 figures

Data-driven ensemble prediction of the global ocean

Authors: Qiusheng Huang, Xiaohui Zhong, Anboyu Guo, Ziyi Peng, Lei Chen, Hao Li

Abstract: Data-driven models have advanced deterministic ocean forecasting, but extending machine learning to probabilistic global ocean prediction remains an open challenge. Here we introduce FuXi-ONS, the first machine-learning ensemble forecasting system for the global ocean, providing 5-day forecasts on a global 1° grid up to 365 days for sea-surface temperature, sea-surface height, subsurface temperatu… ▽ More Data-driven models have advanced deterministic ocean forecasting, but extending machine learning to probabilistic global ocean prediction remains an open challenge. Here we introduce FuXi-ONS, the first machine-learning ensemble forecasting system for the global ocean, providing 5-day forecasts on a global 1° grid up to 365 days for sea-surface temperature, sea-surface height, subsurface temperature, salinity and ocean currents. Rather than relying on repeated integration of computationally expensive numerical models, FuXi-ONS learns physically structured perturbations and incorporates an atmospheric encoding module to stabilize long-range forecasts. Evaluated against GLORYS12 reanalysis, FuXi-ONS improves both ensemble-mean skill and probabilistic forecast quality relative to deterministic and noise-perturbed baselines, and shows competitive performance against established seasonal forecast references for SST and Niño3.4 variability, while running orders of magnitude faster than conventional ensemble systems. These results provide a strong example of machine learning advancing a core problem in ocean science, and establish a practical path toward efficient probabilistic ocean forecasting and climate risk assessment. △ Less

Submitted 19 March, 2026; originally announced March 2026.

Low-cost cross-correlation noise setup for measuring the Boltzmann constant and the elementary charge

Authors: Zitong Peng, Jie Zheng, Xiaokai Yue

Abstract: We present a low-cost experimental setup to measure the Boltzmann constant (kB) and the elementary charge (e) through thermal and shot noise, achieving relative accuracies of up to 1%. The system utilizes a cost-effective ADC module integrated with a carefully selected low-noise audio operational amplifier, resulting in a simple and compact circuit design that better satisfies experimental require… ▽ More We present a low-cost experimental setup to measure the Boltzmann constant (kB) and the elementary charge (e) through thermal and shot noise, achieving relative accuracies of up to 1%. The system utilizes a cost-effective ADC module integrated with a carefully selected low-noise audio operational amplifier, resulting in a simple and compact circuit design that better satisfies experimental requirements. Furthermore, the approach employs a dual-channel sampling method to measure cross-correlation noise, thereby significantly reducing the uncorrelated background noise of the device and improving the signal-to-noise ratio. The noise measurement methodology offers an intuitive demonstration of microscopic fluctuations, making it a valuable teaching tool. In addition, the experimental setup employs standard electronic components, is low cost and robust, making it well-suited for widespread adoption in university and even high school laboratories. △ Less

Submitted 16 March, 2026; originally announced March 2026.

Multimodal Modular Chain of Thoughts in Energy Performance Certificate Assessment

Authors: Zhen Peng, Peter J. Bentley

Abstract: Accurate evaluation of building energy performance remains challenging in regions where scalable Energy Performance Certificate (EPC) assessments are unavailable. This paper presents a cost-efficient framework that leverages Vision-Language models for automated EPC pre-assessment from limited visual information. The proposed Multimodal Modular Chain of Thoughts (MMCoT) architecture decomposes EPC… ▽ More Accurate evaluation of building energy performance remains challenging in regions where scalable Energy Performance Certificate (EPC) assessments are unavailable. This paper presents a cost-efficient framework that leverages Vision-Language models for automated EPC pre-assessment from limited visual information. The proposed Multimodal Modular Chain of Thoughts (MMCoT) architecture decomposes EPC estimation into intermediate reasoning stages and explicitly propagates inferred attributes across tasks using structured prompting. Experiments on a multimodal dataset of 81 residential properties in the United Kingdom show that MMCoT achieves statistically significant improvements over instruction-only prompting for EPC estimation. Analysis based on accuracy, recall, mean absolute error, and confusion matrices indicate that the proposed approach captures the ordinal structure of EPC ratings, with most errors occurring between adjacent classes. These results suggest that modular prompt-based reasoning offers a promising direction for low-cost EPC pre-assessment in data-scarce settings. △ Less

Submitted 20 February, 2026; originally announced March 2026.

Enhancing Microwave Heating Uniformity in Cavities Using a 2-bit Coding Metasurface

Authors: Zhongyin Peng, Chengrong Wang, Changjun Liu, Xiang Zhao, Liping Yan

Abstract: A novel method for enhancing microwave heating uniformity using a 2-bit coding metasurface is proposed. This metasurface is specially designed to scatter incident waves into multiple directions at 2.45 GHz rather than just one, significantly improving the electric field distribution uniformity within a cavity, and eliminating the need to redesign the cavity itself or modify the power excitation. S… ▽ More A novel method for enhancing microwave heating uniformity using a 2-bit coding metasurface is proposed. This metasurface is specially designed to scatter incident waves into multiple directions at 2.45 GHz rather than just one, significantly improving the electric field distribution uniformity within a cavity, and eliminating the need to redesign the cavity itself or modify the power excitation. Simulated results demonstrate a reduction in the coefficient of variation (COV) of potato temperature from 0.694 to 0.461, indicating enhanced heating uniformity while maintaining efficiency. Additionally, the measured potato temperatures show excellent agreement with the simulated results, validating the effectiveness of the proposed method. △ Less

Submitted 26 December, 2025; originally announced December 2025.

Journal ref: IEEE Microwave and Wireless Technology Letters ( Volume: 35, Issue: 1, January 2025)

Particle Builder A Board Game for the Teaching of the Standard Model of Particle Physics at a Secondary Level

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

Abstract: 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. 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. △ Less

Submitted 26 November, 2025; originally announced November 2025.

Initial performance results of the JUNO detector

Authors: Angel Abusleme, Thomas Adam, Kai Adamowicz, David Adey, Shakeel Ahmad, Rizwan Ahmed, Timo Ahola, Sebastiano Aiello, Fengpeng An, Guangpeng An, Costas Andreopoulos, Giuseppe Andronico, João Pedro Athayde Marcondes de André, Nikolay Anfimov, Vito Antonelli, Tatiana Antoshkina, Burin Asavapibhop, Didier Auguste, Margherita Buizza Avanzini, Andrej Babic, Jingzhi Bai, Weidong Bai, Nikita Balashov, Roberto Barbera, Andrea Barresi , et al. (1114 additional authors not shown)

Abstract: The Jiangmen Underground Neutrino Observatory (JUNO) started physics data taking on 26 August 2025. JUNO consists of a 20-kton liquid scintillator central detector, surrounded by a 35 kton water pool serving as a Cherenkov veto, and almost 1000 m$^2$ of plastic scintillator veto on top. The detector is located in a shallow underground laboratory with an overburden of 1800 m.w.e. This paper present… ▽ More The Jiangmen Underground Neutrino Observatory (JUNO) started physics data taking on 26 August 2025. JUNO consists of a 20-kton liquid scintillator central detector, surrounded by a 35 kton water pool serving as a Cherenkov veto, and almost 1000 m$^2$ of plastic scintillator veto on top. The detector is located in a shallow underground laboratory with an overburden of 1800 m.w.e. This paper presents the performance results of the detector, extensively studied during the commissioning of the water phase, the subsequent liquid scintillator filling phase, and the first physics runs. The liquid scintillator achieved an attenuation length of 20.6 m at 430 nm, while the high coverage PMT system and scintillator together yielded about 1785 photoelectrons per MeV of energy deposit at the detector centre, measured using the 2.223 MeV $γ$ from neutron captures on hydrogen with an Am-C calibration source. The reconstructed energy resolution is 3.4% for two 0.511 MeV $γ$ at the detector centre and 2.9% for the 0.93 MeV quenched Po-214 alpha decays from natural radioactive sources. The energy nonlinearity is calibrated to better than 1%. Intrinsic contaminations of U-238 and Th-232 in the liquid scintillator are below 10$^{-16}$ g/g, assuming secular equilibrium. The water Cherenkov detector achieves a muon detection efficiency better than 99.9% for muons traversing the liquid scintillator volume. During the initial science runs, the data acquisition duty cycle exceeded 97.8%, demonstrating the excellent stability and readiness of JUNO for high-precision neutrino physics. △ Less

Submitted 18 November, 2025; originally announced November 2025.

Comments: 38 pages, 23 figures

Dual slow-light enhanced photothermal gas spectroscopy on a silicon chip

Authors: Kaiyuan Zheng, Zihang Peng, Hanyu Liao, Yijun Huang, Haihong Bao, Shuangxiang Zhao, Yu Zhang, Chuantao Zheng, Yiding Wang, Wei Jin

Abstract: Integrated photonic sensors have attracted significant attention recently for their potential for high-density integration. However, they face challenges in sensing gases with high sensitivity due to weak light-gas interaction. Slow light, which dramatically intensifies light-matter interaction through spatial compression of optical energy, provides a promising solution. Herein, we demonstrate a d… ▽ More Integrated photonic sensors have attracted significant attention recently for their potential for high-density integration. However, they face challenges in sensing gases with high sensitivity due to weak light-gas interaction. Slow light, which dramatically intensifies light-matter interaction through spatial compression of optical energy, provides a promising solution. Herein, we demonstrate a dual slow-light scheme for enhancing the sensitivity of photothermal spectroscopy (PTS) with a suspended photonic crystal waveguide (PhCW) on a CMOS-compatible silicon platform. By tailoring the dispersion of the PhCW to generate structural slow light to enhance pump absorption and probe phase modulation, we achieve a photothermal efficiency of 3.6x10-4 rad cm ppm-1 mW-1 m-1, over 1-3 orders of magnitude higher than the strip waveguides and optical fibers. With a 1-mm-long sensing PhCW incorporated in a stabilized on-chip Mach-Zehnder interferometer with a footprint of 0.6 mm2, we demonstrate acetylene detection with a sensitivity of 1.4x10-6 in terms of noise-equivalent absorption and length product (NEAL), the best among the reported photonic waveguide gas sensors to our knowledge. The dual slow-light enhanced PTS paves the way for integrated photonic gas sensors with high sensitivity, miniaturization, and cost-effective mass production. △ Less

Submitted 10 November, 2025; originally announced November 2025.

Prospects for geoneutrino detection with JUNO

Authors: Thomas Adam, Shakeel Ahmad, Rizwan Ahmed, Fengpeng An, João Pedro Athayde Marcondes de André, Costas Andreopoulos, Giuseppe Andronico, Nikolay Anfimov, Vito Antonelli, Tatiana Antoshkina, Didier Auguste, Marcel Büchner, Weidong Bai, Nikita Balashov, Andrea Barresi, Davide Basilico, Eric Baussan, Marco Beretta, Antonio Bergnoli, Nikita Bessonov, Daniel Bick, Lukas Bieger, Svetlana Biktemerova, Thilo Birkenfeld, Simon Blyth , et al. (605 additional authors not shown)

Abstract: Geoneutrinos, which are antineutrinos emitted during the decay of long-lived radioactive elements inside Earth, serve as a unique tool for studying the composition and heat budget of our planet. The Jiangmen Underground Neutrino Observatory (JUNO) experiment in China, which has recently completed construction, is expected to collect a sample comparable in size to the entire existing world geoneutr… ▽ More Geoneutrinos, which are antineutrinos emitted during the decay of long-lived radioactive elements inside Earth, serve as a unique tool for studying the composition and heat budget of our planet. The Jiangmen Underground Neutrino Observatory (JUNO) experiment in China, which has recently completed construction, is expected to collect a sample comparable in size to the entire existing world geoneutrino dataset in less than a year. This paper presents an updated estimation of sensitivity to geoneutrinos of JUNO using the best knowledge available to date about the experimental site, the surrounding nuclear reactors, the detector response uncertainties, and the constraints expected from the TAO satellite detector. To facilitate comparison with present and future geological models, our results cover a wide range of predicted signal strengths. Despite the significant background from reactor antineutrinos, the experiment will measure the total geoneutrino flux with a precision comparable to that of existing experiments within its first few years, ultimately achieving a world-leading precision of about 8% over ten years. The large statistics of JUNO will also allow separation of the Uranium-238 and Thorium-232 contributions with unprecedented precision, providing crucial constraints on models of formation and composition of Earth. Observation of the mantle signal above the lithospheric flux will be possible but challenging. For models with the highest predicted mantle concentrations of heat-producing elements, a 3-sigma detection over six years requires knowledge of the lithospheric flux to within 15%. Together with complementary measurements from other locations, the geoneutrino results of JUNO will offer cutting-edge, high-precision insights into the interior of Earth, of fundamental importance to both the geoscience and neutrino physics communities. △ Less

Submitted 10 November, 2025; originally announced November 2025.

Comments: 32 pages, with 13 figures and 5 tables

Electrochemical properties of solid oxide fuel cells under the coupling effect of airflow pattern and airflow velocity

Authors: Wang Hao, Xie Jiamiao, Hao Wenqian, Li Jingyang, Zhang Peng, Ma Xiaofan, Liu Fu, Wang Xu

Abstract: Under the dual background of deep adjustment of global energy pattern and severe challenges of environmental problems, solid oxide fuel cell (SOFC) has become the focus of research on efficient and clean energy conversion technology due to its many excellent characteristics. The electrochemical performance of SOFC is affected by various factors such as gas flow pattern (co-flow, counter-flow, cros… ▽ More Under the dual background of deep adjustment of global energy pattern and severe challenges of environmental problems, solid oxide fuel cell (SOFC) has become the focus of research on efficient and clean energy conversion technology due to its many excellent characteristics. The electrochemical performance of SOFC is affected by various factors such as gas flow pattern (co-flow, counter-flow, cross-flow), flow rate (cathode and anode channel gases), and operating voltage. Accurately analysing the variation of electrochemical indexes with each factor is the basis for proposing the design scheme of high efficiency reaction of the cell. Therefore, a three-dimensional multi-field coupling model of SOFC is established in this study, and the model parameters and boundary conditions covering electrochemistry, gas flow, substance diffusion, etc. are set to study the influence of the coupling between factors on the electrochemical performance of the cell. These results show that with the decrease of operating voltage, the electrochemical reaction rate of the cell increases significantly, the gas mole fraction gradient increases, and the inhomogeneity of the electrolyte current density distribution is enhanced. Under low-voltage operating conditions, the cross-flow flow pattern shows better electrochemical performance advantages, and its power density profile takes the lead in different current density intervals. With the increase of the flow rate of the flow channel gas, the output power density curve of the cell shows an overall upward trend, and then the driving effect of the flow rate increase on the power density increase is gradually weakened due to the saturated cathodic reaction. This study reveals the influence of the coupling of flow pattern, flow rate and voltage on the electrochemical performance of SOFC, and provides guidance for the commercial application of SOFC. △ Less

Submitted 1 November, 2025; originally announced November 2025.

Comments: 28 pages,14 figures

Journal ref: Acta Phys. Sin., 2025, 74(11): 118201

Photonic scattering in 2D waveguide QED: Quantum Goos-Hänchen shift

Authors: Yongguan Ke, Zhenzhi Peng, Muhib Ullah, Chaohong Lee

Abstract: Quantum emitters coupled to traveling photons in waveguides, known as waveguide quantum electrodynamics (WQED), offer a powerful platform for understanding light-matter interactions and underpinning emergent quantum technologies. While WQED has been extensively studied in one dimension, two-dimensional (2D) WQED remains largely unexplored, where novel photonic scattering phenomena unique to higher… ▽ More Quantum emitters coupled to traveling photons in waveguides, known as waveguide quantum electrodynamics (WQED), offer a powerful platform for understanding light-matter interactions and underpinning emergent quantum technologies. While WQED has been extensively studied in one dimension, two-dimensional (2D) WQED remains largely unexplored, where novel photonic scattering phenomena unique to higher dimensions are expected. Here, we present a comprehensive scattering theory for 2D WQED based on the Green function method. We show that the mean displacement between emitted and injected photons serves as a quantum analogue of the Goos-Hänchen shift. When a photon is injected into a single off-centered port, the quantum Goos-Hänchen (QGH) shift can be enhanced in backward scattering under resonant conditions with subradiant states. When a photon is injected into the center port, there is no QGH shift due to the mirror symmetry of structure. However, for multiple-port injection with transverse momentum, the QGH shift is recovered and proportional to the derivative of phase with respect to transverse momentum. Unlike the classical Goos-Hänchen shift, these effects can be flexibly tuned by the injected photon's frequency. Our work provides a general framework for exploring and manipulating photonic scattering in complex WQED networks. △ Less

Submitted 22 October, 2025; originally announced October 2025.

Comments: Any comments and suggestions are welcome

Enabling High-Quality In-the-Wild Imaging from Severely Aberrated Metalens Bursts

Authors: Debabrata Mandal, Zhihan Peng, Yujie Wang, Praneeth Chakravarthula

Abstract: We tackle the challenge of robust, in-the-wild imaging using ultra-thin nanophotonic metalens cameras. Meta-lenses, composed of planar arrays of nanoscale scatterers, promise dramatic reductions in size and weight compared to conventional refractive optics. However, severe chromatic aberration, pronounced light scattering, narrow spectral bandwidth, and low light efficiency continue to limit their… ▽ More We tackle the challenge of robust, in-the-wild imaging using ultra-thin nanophotonic metalens cameras. Meta-lenses, composed of planar arrays of nanoscale scatterers, promise dramatic reductions in size and weight compared to conventional refractive optics. However, severe chromatic aberration, pronounced light scattering, narrow spectral bandwidth, and low light efficiency continue to limit their practical adoption. In this work, we present an end-to-end solution for in-the-wild imaging that pairs a metalens several times thinner than conventional optics with a bespoke multi-image restoration framework optimized for practical metalens cameras. Our method centers on a lightweight convolutional network paired with a memory-efficient burst fusion algorithm that adaptively corrects noise, saturation clipping, and lens-induced distortions across rapid sequences of extremely degraded metalens captures. Extensive experiments on diverse, real-world handheld captures demonstrate that our approach consistently outperforms existing burst-mode and single-image restoration techniques.These results point toward a practical route for deploying metalens-based cameras in everyday imaging applications. △ Less

Submitted 11 October, 2025; originally announced October 2025.

A Simultaneous Synergistic Protection Mechanism in Hybrid Perovskite-Organic Multi-junctions Enables Long-Term Stable and Efficient Tandem Solar Cells

Authors: Chao Liu, Kaicheng Zhang, Xin Zhou, Mingjian Wu, Paul Weitz, Shudi Qiu, Andrej Vincze, Yuchen Bai, Michael A. Anderson, Johannes Frisch, Regan G. Wilks, Marcus Bar, Zijian Peng, Chaohui Li, Jingjing Tian, Jiyun Zhang, Jianchang Wu, Jonas Englhard, Thomas Heumuller, Jens Hauch, Yixing Huang, Ning Li, Julien Bachmann, Erdmann Spiecker, Christoph J. Brabec

Abstract: Perovskite-organic tandem solar cells (P-O TSCs) hold great promise for next-generation thin-film photovoltaics, with steadily improving power conversion efficiency (PCE). However, the development of optimal interconnecting layers (ICLs) remains one major challenge for further efficiency gains, and progress in understanding the improved long-term stability of P-O tandem configuration has been lagg… ▽ More Perovskite-organic tandem solar cells (P-O TSCs) hold great promise for next-generation thin-film photovoltaics, with steadily improving power conversion efficiency (PCE). However, the development of optimal interconnecting layers (ICLs) remains one major challenge for further efficiency gains, and progress in understanding the improved long-term stability of P-O tandem configuration has been lagging. In this study, we experimentally investigate the enhanced stability of p-i-n P-O TSCs employing a simplified C60/atomic-layer-deposition (ALD) SnOx/PEDOT: PSS ICL without an additional charge recombination layer (CRL), which achieve an averaged efficiency of 25.12% and a hero efficiency of 25.5%. Our finding discovers that the recrystallization of C60, a widely used electron transport layer in perovskite photovoltaics, leads to the formation of grain boundaries during operation, which act as migration channels for the interdiffusion of halide and Ag ions. Critically, we demonstrate for the first time that the tandem device architecture, incorporating organic semiconductor layers, effectively suppresses the bi-directional ion diffusion and mitigates electrode corrosion. Thus, the P-O TSC establishes a mutual protection system: the organic layers stabilize the perovskite sub-cell by suppressing ion diffusion-induced degradation, and the perovskite layer shields the organic sub-cell from spectrally induced degradation. The simultaneous synergistic protection mechanism enables P-O TSCs to achieve exceptional long-term operational stability, retaining over 91% of their initial efficiency after 1000 hours of continuous metal-halide lamp illumination, and to exhibit minimal fatigue after 86 cycles (2067 hours) of long-term diurnal (12/12-hour) testing. These results demonstrate that tandem cells significantly outperform their single-junction counterparts in both efficiency and stability. △ Less

Submitted 9 October, 2025; originally announced October 2025.

Design, waterproofing, and mass production of the 3-inch PMT frontend system of JUNO

Authors: Jilei Xu, Miao He, Cédric Cerna, Yongbo Huang, Thomas Adam, Shakeel Ahmad, Rizwan Ahmed, Fengpeng An, Costas Andreopoulos, Giuseppe Andronico, João Pedro Athayde Marcondes de André, Nikolay Anfimov, Vito Antonelli, Tatiana Antoshkina, Didier Auguste, Weidong Bai, Nikita Balashov, Andrea Barresi, Davide Basilico, Eric Baussan, Marco Beretta, Antonio Bergnoli, Nikita Bessonov, Daniel Bick, Lukas Bieger , et al. (609 additional authors not shown)

Abstract: Over 25,600 3-inch photomultiplier tubes (PMTs) have been instrumented for the central detector of the Jiangmen Underground Neutrino Observatory. Each PMT is equipped with a high-voltage divider and a frontend cable with waterproof sealing. Groups of sixteen PMTs are connected to the underwater frontend readout electronics via specialized multi-channel waterproof connectors. This paper outlines th… ▽ More Over 25,600 3-inch photomultiplier tubes (PMTs) have been instrumented for the central detector of the Jiangmen Underground Neutrino Observatory. Each PMT is equipped with a high-voltage divider and a frontend cable with waterproof sealing. Groups of sixteen PMTs are connected to the underwater frontend readout electronics via specialized multi-channel waterproof connectors. This paper outlines the design and mass production processes for the high-voltage divider, the cable and connector, as well as the waterproof potting of the PMT bases. The results of the acceptance tests of all the integrated PMTs are also presented. △ Less

Submitted 22 January, 2026; v1 submitted 7 October, 2025; originally announced October 2025.

Complex Band Structure and Bound States in the Continuum: A Unified Theoretical Framework

Authors: Jie Liu, Ziyun Peng, Qianju Song, Ang Chen, Liping Yang, Chunxiong Zheng, Dezhuan Han

Abstract: Band structure analysis is central to understanding wave propagation in periodic media; however, it becomes challenging in open systems owing to energy leakage. Photonic crystal (PhC) slabs exemplify such systems, featuring periodicity in the $x$-$y$ plane and finite extent in the $z$-direction, and supporting diverse guided-mode resonances whose interactions give rise to phenomena such as bound s… ▽ More Band structure analysis is central to understanding wave propagation in periodic media; however, it becomes challenging in open systems owing to energy leakage. Photonic crystal (PhC) slabs exemplify such systems, featuring periodicity in the $x$-$y$ plane and finite extent in the $z$-direction, and supporting diverse guided-mode resonances whose interactions give rise to phenomena such as bound states in the continuum (BICs), exceptional points (EPs), and circular polarisation states. Although numerical simulations can reveal these effects, effective non-Hermitian Hamiltonians are often employed to elucidate the underlying physical mechanisms. This approach, however, relies on manually selected resonant modes and may suffer from basis incompleteness. Here, a systematic first-principles approach is presented to derive the complex band structure. The minimal channels in the scattering matrix, either open or closed, are determined by the number of propagating bulk Bloch waves. The interactions between these waves fully reveal the complex band structure. For instance, two Bloch waves predict the leading-order imaginary frequency $ω''$ and identify accidental BICs, each associated with a dual Fabry--Pérot mode, whereas three waves reveal robust Friedrich--Wintgen and symmetry-protected BICs together with the associated linewidth behaviours. Orthogonally polarised waves are further incorporated to characterise far-field polarisation and EPs. When extended to a two-dimensional periodic structure, this framework accurately predicts $ω''$, encompasses all known BICs, and tracks their evolution with system parameters. Overall, this first-principles approach provides a unified foundation for studying complex band structure and facilitates the exploration of light confinement in periodic media. △ Less

Submitted 19 March, 2026; v1 submitted 3 September, 2025; originally announced September 2025.

Comments: Accepted for publication in Reports on Progress in Physics

Journal ref: Rep. Prog. Phys. 89 037901 (2026)

A Novel Nonlinear IP$_3$R State Transition Model and Calcium Oscillation

Authors: Zhao-Yu Peng, Han-Yu Jiang, Jun He

Abstract: We present a novel nonlinear state transition model for inositol 1,4,5-trisphosphate receptors (IP$_3$Rs) that incorporates a pre-activated state, as suggested by electron microscopy observations. Our model provides a theoretical framework for the biphasic Ca$^{2+}$ dependence of IP$_3$Rs and accurately reproduces their experimentally observed state distribution under saturating IP$_3$ conditions.… ▽ More We present a novel nonlinear state transition model for inositol 1,4,5-trisphosphate receptors (IP$_3$Rs) that incorporates a pre-activated state, as suggested by electron microscopy observations. Our model provides a theoretical framework for the biphasic Ca$^{2+}$ dependence of IP$_3$Rs and accurately reproduces their experimentally observed state distribution under saturating IP$_3$ conditions. By integrating receptor dynamics with cytoplasmic and endoplasmic reticulum (ER) calcium exchange, we simulate IP$_3$R-mediated Ca$^{2+}$ oscillations governed by six key conformational states. A pivotal finding is that IP$_3$ regulates these oscillations in a switch-like manner: once a critical IP$_3$ concentration is reached, the system abruptly transitions to sustained, constant-amplitude oscillations that quickly terminate when the concentration exceeds a secondary threshold. These results underscore the crucial role of the pre-activated state in modulating calcium signaling. △ Less

Submitted 18 August, 2025; originally announced August 2025.

Comments: 9 pages, 4 figures

Dispersion of active particles in oscillatory Poiseuille flow

Authors: Vhaskar Chakraborty, Pankaj Mishra, Mingfeng Qiu, Zhiwei Peng

Abstract: Active particles exhibit complex transport dynamics in flows through confined geometries such as channels or pores. In this work, we employ a generalized Taylor dispersion (GTD) theory to study the long-time dispersion behavior of active Brownian particles (ABPs) in an oscillatory Poiseuille flow within a planar channel. We quantify the time-averaged longitudinal dispersion coefficient as a functi… ▽ More Active particles exhibit complex transport dynamics in flows through confined geometries such as channels or pores. In this work, we employ a generalized Taylor dispersion (GTD) theory to study the long-time dispersion behavior of active Brownian particles (ABPs) in an oscillatory Poiseuille flow within a planar channel. We quantify the time-averaged longitudinal dispersion coefficient as a function of the flow speed, flow oscillation frequency, and particle activity. In the weak-activity limit, asymptotic analysis shows that activity can either enhance or hinder the dispersion compared to the passive case. For arbitrary activity levels, we numerically solve the GTD equations and validate the results with Brownian dynamics simulations. We show that the dispersion coefficient could vary non-monotonically with both the flow speed and particle activity. Furthermore, the dispersion coefficient shows an oscillatory behavior as a function of the flow oscillation frequency, exhibiting distinct minima and maxima at different frequencies. The observed oscillatory dispersion results from the interplay between self-propulsion and oscillatory flow advection -- a coupling absent in passive or steady systems. Our results show that time-dependent flows can be used to tune the dispersion of active particles in confinement. △ Less

Submitted 11 May, 2026; v1 submitted 22 July, 2025; originally announced July 2025.

Comments: 28 pages, 12 figures

Journal ref: Journal of Fluid Mechanics 1034 (2026): A59

Purcell enhancement of photogalvanic currents in a van der Waals plasmonic self-cavity

Authors: Xinyu Li, Jesse Hagelstein, Gunda Kipp, Felix Sturm, Kateryna Kusyak, Yunfei Huang, Benedikt F. Schulte, Alexander M. Potts, Jonathan Stensberg, Victoria Quirós-Cordero, Chiara Trovatello, Zhi Hao Peng, Chaowei Hu, Jonathan M. DeStefano, Michael Fechner, Takashi Taniguchi, Kenji Watanabe, P. James Schuck, Xiaodong Xu, Jiun-Haw Chu, Xiaoyang Zhu, Angel Rubio, Marios H. Michael, Matthew W. Day, Hope M. Bretscher , et al. (1 additional authors not shown)

Abstract: Cavities provide a means to manipulate the optical and electronic responses of quantum materials by selectively enhancing light-matter interaction at specific frequencies and momenta. While cavities typically involve external structures, exfoliated flakes of van der Waals (vdW) materials can form intrinsic self-cavities due to their small finite dimensions, confining electromagnetic fields into pl… ▽ More Cavities provide a means to manipulate the optical and electronic responses of quantum materials by selectively enhancing light-matter interaction at specific frequencies and momenta. While cavities typically involve external structures, exfoliated flakes of van der Waals (vdW) materials can form intrinsic self-cavities due to their small finite dimensions, confining electromagnetic fields into plasmonic cavity modes, characterized by standing-wave current distributions. While cavity-enhanced phenomena are well-studied at optical frequencies, the impact of self-cavities on nonlinear electronic responses--such as photogalvanic currents--remains largely unexplored, particularly in the terahertz regime, critical for emerging ultrafast optoelectronic technologies. Here, we report a self-cavity-induced Purcell enhancement of photogalvanic currents in the vdW semimetal WTe$_2$. Using ultrafast optoelectronic circuitry, we measured coherent near-field THz emission resulting from nonlinear photocurrents excited at the sample edges. We observed enhanced emission at finite frequencies, tunable via excitation fluence and sample geometry, which we attribute to plasmonic interference effects controlled by the cavity boundaries. We developed an analytical theory that captures the cavity resonance conditions and spectral response across multiple devices. Our findings establish WTe$_2$ as a bias-free, geometry-tunable THz emitter and demonstrate the potential of self-cavity engineering for controlling nonlinear, nonequilibrium dynamics in quantum materials. △ Less

Submitted 10 July, 2025; originally announced July 2025.

JUNO 20-inch PMT and electronics system characterization using large pulses of PMT dark counts at the Pan-Asia testing platform

Authors: Caimei Liu, Min Li, Narongkiat Rodphai, Zhimin Wang, Jun Hu, Nikolay Anfimov, Lei Fan, Alberto Garfagnini, Guanghua Gong, Shaojing Hou, Xiaolu Ji, Xiaoshan Jiang, Denis Korablev, Tobias Lachenmaier, Si Ma, Xiaoyan Ma, Zhe Ning, Alexander G. Olshevskiy, Zhaoyuan Peng, Zhonghua Qin, Tobias Sterr, Yunhua Sun, Alexander Felix Tietzsch, Jun Wang, Wei Wang , et al. (13 additional authors not shown)

Abstract: The main goal of the JUNO experiment is to determine the neutrino mass ordering with a 20kt liquid-scintillator detector. The 20-inch PMT and its 1F3 (one for three) electronics are crucial to realize the excellent energy resolution of at least 3% at 1MeV. The knowledge on the PMT and 1F3 electronics response is critical for detector performance understanding. A study of the JUNO 20-inch PMT and 1… ▽ More The main goal of the JUNO experiment is to determine the neutrino mass ordering with a 20kt liquid-scintillator detector. The 20-inch PMT and its 1F3 (one for three) electronics are crucial to realize the excellent energy resolution of at least 3% at 1MeV. The knowledge on the PMT and 1F3 electronics response is critical for detector performance understanding. A study of the JUNO 20-inch PMT and 1F3 electronics system characterization is presented using large pulses of PMT dark count at the Pan-Asia testing platform in China. Thanks to its broad amplitude range and high rate, the large pulse signals are also used to investigate the PMT after pulse response. △ Less

Submitted 14 September, 2025; v1 submitted 26 June, 2025; originally announced June 2025.

Dark Count Rate Stability of JUNO 20-inch PMTs in Mass Testing

Authors: Min Li, Narongkiat Rodphai, Caimei Liu, Zhimin Wang, Zhaoyuan Peng, Jun Wang, Nikolay Anfimov, Denis Korablev, Tobias Lachenmaier, Alexander G. Olshevskiy, Zhonghua Qin, Tobias Sterr, Alexander Felix Tietzsch, Rong Zhao, Wei Wang, Kaile Wen, Bjoern Soenke Wonsak, Wan Xie, Meihang Xu, Yu Zhang

Abstract: The Jiangmen Underground Neutrino Observatory (JUNO) is an ambitious multipurpose neutrino experiment designed to determine the neutrino mass ordering, with an impressive energy resolution goal of at least 3% at 1 MeV. To achieve a photon detection coverage of approximately 75%, JUNO will utilize two types of 20-inch photomultiplier tubes (PMTs): the large PMT (LPMT) and the microchannel plate PMT… ▽ More The Jiangmen Underground Neutrino Observatory (JUNO) is an ambitious multipurpose neutrino experiment designed to determine the neutrino mass ordering, with an impressive energy resolution goal of at least 3% at 1 MeV. To achieve a photon detection coverage of approximately 75%, JUNO will utilize two types of 20-inch photomultiplier tubes (PMTs): the large PMT (LPMT) and the microchannel plate PMT (MCP-PMT). A significant concern in high-precision neutrino measurements is the dark count rate (DCR) of PMTs, which introduces noise that can adversely affect energy measurement accuracy. During the mass testing phase of the JUNO 20-inch PMTs, comprehensive measurements of the DCR were undertaken. These measurements not only captured the DCR values of individual PMTs but also examined the stability and temperature dependence of the DCR at an operating gain of (1x10^7). This paper presents a detailed characterization of the DCR of the JUNO 20-inch PMTs, investigating factors such as cooling time, temperature variations, and long-term stability using the JUNO Pan-Asia PMT testing facilities. The results reveal distinct DCR characteristics between the two types of PMTs, providing valuable insights into the nature of DCR and its implications for JUNO's scientific objectives. In addition to performance characterization, we implemented a monitoring system to track DCR stability over time. Notably, several spikes in DCR were identified, prompting a preliminary investigation into their causes. Potential factors contributing to these spikes, such as flasher events, were explored using coincidence rate analysis and complementary imaging techniques. The findings from this study are crucial for optimizing the performance of PMTs in JUNO, ultimately aiding the experiment in achieving its goals related to neutrino physics. △ Less

Submitted 11 August, 2025; v1 submitted 18 June, 2025; originally announced June 2025.

Comments: 24 pages, 19 figures

Particle Builder -- Learn about the Standard Model while playing against an AI

Authors: Mohammad Attar, Andrew Carse, Yeming Chen, Thomas Green, Jeong-Yeon Ha, Yanbai Jin, Amy McWilliams, Theirry Panggabean, Zhengyu Peng, Lujin Sun, Jing Ru, Jiacheng She, Jialin Wang, Zilun Wei, Jiayuan Zhu, Lachlan McGinness

Abstract: Particle Builder Online is a web-based education game designed for high school physics students. Students can play against an AI opponent or peers to familiarise themselves with the Standard Model of Particle Physics. The game is aimed at a high school level and tailored to the International Baccalaureate and the Australian Curriculum. Students from four schools in Canberra took pre/post-tests and… ▽ More Particle Builder Online is a web-based education game designed for high school physics students. Students can play against an AI opponent or peers to familiarise themselves with the Standard Model of Particle Physics. The game is aimed at a high school level and tailored to the International Baccalaureate and the Australian Curriculum. Students from four schools in Canberra took pre/post-tests and a survey while completing a lesson where they played Particle Builder. Students' understanding of particle physics concepts improved significantly. Students found the game more enjoyable and effective than regular classroom lessons. △ Less

Submitted 27 May, 2025; originally announced June 2025.

Comments: This demo has been accepted for presentation at the AIED 2025 Interactive Events Track

Adaptive and hybrid reduced order models to mitigate Kolmogorov barrier in a multiscale kinetic transport equation

Authors: Tianyu Jin, Zhichao Peng, Yang Xiang

Abstract: In this work, we develop reduced order models (ROMs) to predict solutions to a multiscale kinetic transport equation with a diffusion limit under the parametric setting. When the underlying scattering effect is not sufficiently strong, the system governed by this equation exhibits transport-dominated behavior. Suffering from the Kolmogorov barrier for transport-dominant problems, classical linear… ▽ More In this work, we develop reduced order models (ROMs) to predict solutions to a multiscale kinetic transport equation with a diffusion limit under the parametric setting. When the underlying scattering effect is not sufficiently strong, the system governed by this equation exhibits transport-dominated behavior. Suffering from the Kolmogorov barrier for transport-dominant problems, classical linear ROMs may become inefficient in this regime. To address this issue, we first develop a piecewise linear ROM by introducing a novel goal-oriented adaptive time partitioning strategy. To avoid local over-refinement or under-refinement, we propose an adaptive coarsening and refinement strategy that remains robust with various initial empirical partitions. Additionally, for problems where a local linear approximation is not sufficiently efficient, we further develop a hybrid ROM, which combines autoencoder-based nonlinear ROMs and piecewise linear ROMs. Compared to previous autoencoder-based ROMs, this hybridized method reduces the offline autoencoder's training cost by only applying it to time intervals that are adaptively identified as the most challenging. Numerical experiments demonstrate that our proposed approaches successfully predict full-order solutions at unseen parameter values with both efficiency and accuracy. To the best of our knowledge, this is the first attempt to address the Kolmogorov barrier for multiscale kinetic transport problems with the coexistence of both transport- and diffusion-dominant behaviors. △ Less

Submitted 13 May, 2025; originally announced May 2025.

Elucidating Ion Capture and Transport Mechanisms of Preyssler Anions in Aqueous Solutions Using Biased MACE-Accelerated MD Simulations

Authors: Quadri O. Adewuyi, Suchona Akter, Md Omar Faruque, Dil K. Limbu, Zhonghua Peng, Praveen K. Thallapally, Mohammed R. Momeni

Abstract: Equilibrium and biased MACE accelerated MD simulations in aqueous solutions are performed to investigate the ion capture and transport mechanisms of the {P5W30} Preyssler anion (PA) as the smallest representative member of the extended polyoxometalate (POM) family with an internal cavity. The unique interatomic interactions present in the internal cavity vs. exterior of PA are carefully investigat… ▽ More Equilibrium and biased MACE accelerated MD simulations in aqueous solutions are performed to investigate the ion capture and transport mechanisms of the {P5W30} Preyssler anion (PA) as the smallest representative member of the extended polyoxometalate (POM) family with an internal cavity. The unique interatomic interactions present in the internal cavity vs. exterior of PA are carefully investigated using equilibrium MACE MD simulations for two representative Na(H2O)@PA and Na@PA complexes. Our careful analyses of radial distribution functions and coordination numbers show that the presence of confined water in Na(H2O)@PA has profound modulating effects on the nature of the interactions of the encapsulated ion with the oxygens of the PA cavity. Using well-converged MACE-accelerated multiple walker well-tempered metadynamics simulations, two different associative and dissociative ion transport mechanisms were carefully investigated for Na+ as one of the most abundant and representative ions present in seawater and saline solutions. By comparing systems with and without confined water, it was found that the presence of only one pre-encapsulated confined water in Na(H2O)@PA dramatically changes the free energy landscape of ion transport processes. It was also found that the contraction and dilation of the two windows present in PA directly influence the Na+ and H2O transport. Results from this work are helpful as they show a viable path toward tuning the ion exchange and transport phenomena in aqueous solutions of POM molecular clusters and frameworks. △ Less

Submitted 5 May, 2025; originally announced May 2025.

Journal ref: J. Chem. Phys. 163, 064502 (2025)

Photonic Crystal Microring Resonators on a Hybrid Silicon Nitride-on-Lithium Niobate Platform

Authors: Zhongdi Peng, Rakesh Krishna, Xi Wu, Amir H. Hosseinnia, Tianren Fan, Ali Adibi

Abstract: Photonic-crystal resonators (PhCRs) have been widely used in nonlinear integrated photonics for frequency engineering applications. A microwave-assisted frequency converter based on PhCRs highlights its precise control of frequency (enabled by creation of a pair of supermodes by a corrugated PhCR) and bidirectional frequency conversion. In this paper, we demonstrate a high-quality PhCR on a hybrid… ▽ More Photonic-crystal resonators (PhCRs) have been widely used in nonlinear integrated photonics for frequency engineering applications. A microwave-assisted frequency converter based on PhCRs highlights its precise control of frequency (enabled by creation of a pair of supermodes by a corrugated PhCR) and bidirectional frequency conversion. In this paper, we demonstrate a high-quality PhCR on a hybrid silicon nitride-on-lithium niobate-on-insulator (SiN-on-LNOI) platform for the first time for voltage-driven flexible frequency conversion using the electro-optic effect (0.85 pm/V). The fabricated PhCR has a large supermode splitting bandwidth = 14.6 GHz and an intrinsic quality factor (Q) = 147,000. Using different periodic corrugation amplitudes in the fabricated PhCRs enables the precise control of mode splitting with a ratio of 93.5 MHz/nm between the mode splitting bandwidth and the corrugation amplitude. △ Less

Submitted 1 May, 2025; originally announced May 2025.

Comments: 4 pages, 5 figures

Frequency Comb-based Wavelength Division Multiplexing and Detection without Wavelength Demultiplexers

Authors: Di Che, Zhongdi Peng, Mikael Mazur, Nicolas Fontaine

Abstract: We demonstrate a wavelength division multiplexing (WDM) concept using demultiplexer-free frequency combs at both transmitter and receiver in a 4-wavelength 200-GHz-grid WDM system with flexible symbol rates, aiming to avoid the power-hungry wavelength control on demultiplexers. We demonstrate a wavelength division multiplexing (WDM) concept using demultiplexer-free frequency combs at both transmitter and receiver in a 4-wavelength 200-GHz-grid WDM system with flexible symbol rates, aiming to avoid the power-hungry wavelength control on demultiplexers. △ Less

Submitted 21 April, 2025; originally announced April 2025.

Comments: Published in ECOC'2024, PDP Th3A.6

Hot-electron-injection-induced symmetry breaking in bilayer MoS$_2$ probed by second-harmonic generation

Authors: Zhizi Guan, Zhiwei Peng, David J. Srolovitz, Jacob Khurgin, Dangyuan Lei

Abstract: Symmetry governs the selection rules of light-matter interactions in crystalline materials, making symmetry manipulation a powerful tool for tuning their optical properties. Here, we demonstrate that the hot-electron injection from a plasmonic resonator breaks the centrosymmtry of an adjacent transition metal dichalcogenide bilayer, probed via second-harmonic generation (SHG) in a Au-nanoparticle@… ▽ More Symmetry governs the selection rules of light-matter interactions in crystalline materials, making symmetry manipulation a powerful tool for tuning their optical properties. Here, we demonstrate that the hot-electron injection from a plasmonic resonator breaks the centrosymmtry of an adjacent transition metal dichalcogenide bilayer, probed via second-harmonic generation (SHG) in a Au-nanoparticle@bilayer-MoS$_2$@Au-film hybrid system. Power-dependent SHG measurements exhibit saturation behavior, consistent with a capacitor model where interfacial charge accumulation creates a dynamic barrier limiting further electron injection. Polarization-resolved SHG measurements reveal anisotropic second-order susceptibility response under hot-electron injection, where the contrast between different susceptibility components provides a quantitative measure of symmetry-breaking anisotropy. First-principles calculations elucidate the nonlinear optical responses evolution in bilayer MoS$_2$ and comfirm the anisotropic modification of susceptibility components under hot-electron injection, modeled by a perpendicular electric field. Our work establishes SHG as an effective probe of hot-electron-induced symmetry breaking in 2D materials, demonstrating a promising approach for ultrafast manipulation of material properties through controlled charge injection at the nanoscale. △ Less

Submitted 1 April, 2025; v1 submitted 27 March, 2025; originally announced March 2025.

Nuclear Physics at BRIF

Authors: Wei Nan, Bing Guo, Jie Chen, Baoqun Cui, Wei Fu, Xianlu Jia, Chaoxin Kan, Jiayinghao Li, Yunju Li, Chengjian Lin, Yihui Liu, Nanru Ma, Zhaohua Peng, Yangping Shen, Guofang Song, Jun Su, Bing Tang, Haorui Wang, Youbao Wang, Lei Yang, Xiaofei Yang, Zhiguo Yin, Yun Zheng, Tianjue Zhang, Weiping Liu

Abstract: The Beijing Radioactive Ion-beam Facility (BRIF), which is based on Isotope Separation On-Line (ISOL) technique, consists of a 100 MeV proton cyclotron as the driving accelerator, a two-stage ISOL system for ion separation, a 13-MV tandem accelerator for post-acceleration, a superconducting linac for further boosting beam energies. It is capable of providing ISOL beams in the energy range from 60… ▽ More The Beijing Radioactive Ion-beam Facility (BRIF), which is based on Isotope Separation On-Line (ISOL) technique, consists of a 100 MeV proton cyclotron as the driving accelerator, a two-stage ISOL system for ion separation, a 13-MV tandem accelerator for post-acceleration, a superconducting linac for further boosting beam energies. It is capable of providing ISOL beams in the energy range from 60 to 300 keV, and post-accelerated beams in the energy range from 3 to 10 MeV/u for nuclei with mass numbers of A < 80 by Isotope Separation On-Line (ISOL) technique. For nuclei with A up to 170, energies are still able to reach 3 MeV/u. This facility offers opportunities to address key questions of current interest in nuclear astrophysics, nuclear structure and reactions of unstable nuclei. In this review we present a comprehensive introduction to the BRIF and the typical experimental instruments installed on it, and then summarize current experimental results on unstable Na and Rb isotopes and future plan for further development of the BRIF to improve its performance. △ Less

Submitted 27 June, 2025; v1 submitted 16 March, 2025; originally announced March 2025.

Comments: 82 pages, 77 figures

Hybrid quantum surface acoustic wave with skyrmion qubit for quantum information processing

Authors: Yu-Yuan Chen, Zhihui Peng, Yu-xi Liu

Abstract: Surface acoustic wave (SAW) devices are key components of classical communication systems and recently studied for quantum information processing. We here propose and study a hybrid quantum system composed of skyrmion qubit and a SAW cavity, which supports a number of long-lived phononic modes. The results show that the system allows for strong coupling between skyrmion qubit and single phonon of… ▽ More Surface acoustic wave (SAW) devices are key components of classical communication systems and recently studied for quantum information processing. We here propose and study a hybrid quantum system composed of skyrmion qubit and a SAW cavity, which supports a number of long-lived phononic modes. The results show that the system allows for strong coupling between skyrmion qubit and single phonon of different modes. By manipulating the qubit(s) through a static magnetic field and a time-dependent modulation magnetic field, we further study the interaction between skyrmion qubit and individual phononic modes, phonon-phonon interaction, and qubit-qubit interaction, which operates in strong-coupling regime. The controllability of nanoscale skyrmion qubit and the dense phononic modes of single SAW cavity would make our system have promising applications in large-scale quantum communication and computing. △ Less

Submitted 9 March, 2025; originally announced March 2025.

Comments: 7 pages, 5 figures

Journal ref: Phys. Rev. Lett. 136, 013801 (2026)

Chemically resolved nuclear magnetic resonance spectroscopy by longitudinal magnetization detection with a diamond magnetometer

Authors: Janis Smits, Yaser Silani, Zaili Peng, Bryan A. Richards, Andrew F. McDowell, Joshua T. Damron, Maxwell D. Aiello, Maziar Saleh Ziabari, Andrey Jarmola, Victor M. Acosta

Abstract: Non-inductive magnetometers based on solid-state spins offer a promising solution for small-volume nuclear magnetic resonance (NMR) detection. A remaining challenge is to operate at a sufficiently high magnetic field to resolve chemical shifts at the part-per-billion level. Here, we demonstrate a Ramsey-M_z protocol that uses Ramsey interferometry to convert an analyte's transverse spin precession… ▽ More Non-inductive magnetometers based on solid-state spins offer a promising solution for small-volume nuclear magnetic resonance (NMR) detection. A remaining challenge is to operate at a sufficiently high magnetic field to resolve chemical shifts at the part-per-billion level. Here, we demonstrate a Ramsey-M_z protocol that uses Ramsey interferometry to convert an analyte's transverse spin precession into a longitudinal magnetization (M_z), which is subsequently modulated and detected with a diamond magnetometer. We record NMR spectra at B0=0.32 T with a fractional spectral resolution of ~350 ppb, limited by the stability of the electromagnet bias field. We perform NMR spectroscopy on a ~1 nL detection volume of ethanol and resolve the chemical shift structure with negligible distortion. Through simulation, we show that the protocol can be extended to fields up to B0=3 T, with minimal spectral distortion, using composite nuclear-spin inversion pulses. For sub-nanoliter analyte volumes, we estimate a resolution of ~1 ppb and concentration sensitivity of ~40 mM s^{1/2} is feasible with improvements to the sensor design. Our results establish diamond magnetometers as high-resolution NMR detectors in the moderate magnetic field regime, with potential applications in metabolomics and pharmaceutical research. △ Less

Submitted 3 March, 2025; originally announced March 2025.

Comments: Main text: 5 figures, 7 pages; Total including Appendices: 20 pages, 13 figures, 2 tables, 62 references

Simulation of the Background from $^{13}$C$(α, n)^{16}$O Reaction in the JUNO Scintillator

Authors: JUNO Collaboration, Thomas Adam, Kai Adamowicz, Shakeel Ahmad, Rizwan Ahmed, Sebastiano Aiello, Fengpeng An, Costas Andreopoulos, Giuseppe Andronico, Nikolay Anfimov, Vito Antonelli, Tatiana Antoshkina, João Pedro Athayde Marcondes de André, Didier Auguste, Weidong Bai, Nikita Balashov, Andrea Barresi, Davide Basilico, Eric Baussan, Marco Beretta, Antonio Bergnoli, Nikita Bessonov, Daniel Bick, Lukas Bieger, Svetlana Biktemerova , et al. (608 additional authors not shown)

Abstract: Large-scale organic liquid scintillator detectors are highly efficient in the detection of MeV-scale electron antineutrinos. These signal events can be detected through inverse beta decay on protons, which produce a positron accompanied by a neutron. A noteworthy background for antineutrinos coming from nuclear power reactors and from the depths of the Earth (geoneutrinos) is generated by ($α, n$)… ▽ More Large-scale organic liquid scintillator detectors are highly efficient in the detection of MeV-scale electron antineutrinos. These signal events can be detected through inverse beta decay on protons, which produce a positron accompanied by a neutron. A noteworthy background for antineutrinos coming from nuclear power reactors and from the depths of the Earth (geoneutrinos) is generated by ($α, n$) reactions. In organic liquid scintillator detectors, $α$ particles emitted from intrinsic contaminants such as $^{238}$U, $^{232}$Th, and $^{210}$Pb/$^{210}$Po, can be captured on $^{13}$C nuclei, followed by the emission of a MeV-scale neutron. Three distinct interaction mechanisms can produce prompt energy depositions preceding the delayed neutron capture, leading to a pair of events correlated in space and time within the detector. Thus, ($α, n$) reactions represent an indistinguishable background in liquid scintillator-based antineutrino detectors, where their expected rate and energy spectrum are typically evaluated via Monte Carlo simulations. This work presents results from the open-source SaG4n software, used to calculate the expected energy depositions from the neutron and any associated de-excitation products. Also simulated is a detailed detector response to these interactions, using a dedicated Geant4-based simulation software from the JUNO experiment. An expected measurable $^{13}$C$(α, n)^{16}$O event rate and reconstructed prompt energy spectrum with associated uncertainties, are presented in the context of JUNO, however, the methods and results are applicable and relevant to other organic liquid scintillator neutrino detectors. △ Less

Submitted 2 May, 2025; v1 submitted 2 March, 2025; originally announced March 2025.

Comments: 25 pages, 14 figures, 4 tables

A Test System for the JUNO 20-inch PMTs Prior to Installation

Authors: Zhaoyuan Peng, Haojie Dong, Kaile Wen, Xinzhou Guo, Yanfeng Li, Songyi Li, Zeyuan Feng, Wan Xie, Shenghui Liu, Chao Chen, Xiaochuan Xie, Jun Hu, Lei Fan, Zhonghua Qin

Abstract: The JUNO experiment requires an excellent energy resolution of 3\% at 1 MeV. To achieve this objective, a total of 20,012 20-inch photomultiplier tubes (PMTs) will be deployed for JUNO, comprising 15,012 multi-channel plate (MCP) PMTs and 5,000 dynode PMTs. Currently, JUNO is in the process of detector installation, with PMTs being installed from the top to the bottom of the stainless-steel struct… ▽ More The JUNO experiment requires an excellent energy resolution of 3\% at 1 MeV. To achieve this objective, a total of 20,012 20-inch photomultiplier tubes (PMTs) will be deployed for JUNO, comprising 15,012 multi-channel plate (MCP) PMTs and 5,000 dynode PMTs. Currently, JUNO is in the process of detector installation, with PMTs being installed from the top to the bottom of the stainless-steel structure located in the underground experimental hall. In order to validate the functionality of the PMTs and ensure there are no malfunctions prior to installation, a test system has been established at the JUNO site, and testing is being conducted. This paper presents an overview of the test system and reports on the initial test results. △ Less

Submitted 22 February, 2025; originally announced February 2025.

Universality of the complete-graph Potts model with $0< q \leq 2$

Authors: Zirui Peng, Sheng Fang, Hao Hu, Youjin Deng

Abstract: Universality is a fundamental concept in modern physics. For the $q$-state Potts model, the critical exponents are merely determined by the order-parameter symmetry $S_q$, spatial dimensionality and interaction range, independent of microscopic details. In a simplest and mean-field treatment--i.e., the Potts model on complete graph (CG), the phase transition is further established to be of percola… ▽ More Universality is a fundamental concept in modern physics. For the $q$-state Potts model, the critical exponents are merely determined by the order-parameter symmetry $S_q$, spatial dimensionality and interaction range, independent of microscopic details. In a simplest and mean-field treatment--i.e., the Potts model on complete graph (CG), the phase transition is further established to be of percolation universality for the range of $0 < q <2$. By simulating the CG Potts model in the random-cluster representation, we numerically demonstrate such a hyper-universality that the critical exponents are the same for $0< q <2$ and, moreover, the Ising system ($q = 2$) exhibits a variety of critical geometric properties in percolation universality. On the other hand, many other universal properties in the finite-size scaling (FSS) theory, including Binder-like ratios and distribution function of the order parameter, are observed to be $q$-dependent. Our finding provides valuable insights for the study of critical phenomena in finite spatial dimensions, particularly when the FSS theory is utilized. △ Less

Submitted 28 January, 2025; originally announced January 2025.

Journal ref: Phys. Rev. E 111, 054134 (2025)

Spatiotemporal imaging of nonlinear optics in van der Waals waveguides

Authors: Ding Xu, Zhi Hao Peng, Chiara Trovatello, Shan-Wen Cheng, Xinyi Xu, Aaron Sternbach, Dmitri N. Basov, P. James Schuck, Milan Delor

Abstract: Van der Waals (vdW) semiconductors have emerged as promising platforms for efficient nonlinear optical conversion, including harmonic and entangled photon generation. Although major efforts are devoted to integrating vdW materials in nanoscale waveguides for miniaturization, the realization of efficient, phase-matched conversion in these platforms remains challenging. To address this challenge, we… ▽ More Van der Waals (vdW) semiconductors have emerged as promising platforms for efficient nonlinear optical conversion, including harmonic and entangled photon generation. Although major efforts are devoted to integrating vdW materials in nanoscale waveguides for miniaturization, the realization of efficient, phase-matched conversion in these platforms remains challenging. To address this challenge, we develop a far-field ultrafast imaging method to track the propagation of both fundamental and harmonic waves within vdW waveguides with extreme spatiotemporal resolution. Our approach allows systematic optimization of nonlinear conversion by determining the phase-matching angles, mode profiles, and losses in waveguides without a priori knowledge of material properties. We focus on light propagation in slab waveguides of rhombohedral-stacked MoS2, an emerging vdW semiconductor with giant nonlinear susceptibility. Our results reveal that these waveguides support birefringent phase-matching, demonstrating the material's potential for efficient on-chip nonlinear optics. This work establishes spatiotemporal imaging of light propagation in waveguides as an incisive and general method to identify new materials and architectures for efficient nonlinear nanophotonics. △ Less

Submitted 10 December, 2024; originally announced December 2024.

AAROC: Reduced Over-Collocation Method with Adaptive Time Partitioning and Adaptive Enrichment for Parametric Time-Dependent Equations

Authors: Lijie Ji, Zhichao Peng, Yanlai Chen

Abstract: Nonlinear and nonaffine terms in parametric partial differential equations can potentially lead to a computational cost of a reduced order model (ROM) that is comparable to the cost of the original full order model (FOM). To address this, the Reduced Residual Reduced Over-Collocation method (R2-ROC) is developed as a hyper-reduction method within the framework of the reduced basis method in the co… ▽ More Nonlinear and nonaffine terms in parametric partial differential equations can potentially lead to a computational cost of a reduced order model (ROM) that is comparable to the cost of the original full order model (FOM). To address this, the Reduced Residual Reduced Over-Collocation method (R2-ROC) is developed as a hyper-reduction method within the framework of the reduced basis method in the collocation setting. R2-ROC greedily selects two sets of reduced collocation points based on the (generalized) empirical interpolation method for both solution snapshots and residuals, thereby avoiding the computational inefficiency. The vanilla R2-ROC method can face instability when applied to parametric fluid dynamic problems. To address this, an adaptive enrichment strategy has been proposed to stabilize the ROC method. However, this strategy can involve in an excessive number of reduced collocation points, thereby negatively impacting online efficiency. To ensure both efficiency and accuracy, we propose an adaptive time partitioning and adaptive enrichment strategy-based ROC method (AAROC). The adaptive time partitioning dynamically captures the low-rank structure, necessitating fewer reduced collocation points being sampled in each time segment. Numerical experiments on the parametric viscous Burgers' equation and lid-driven cavity problems demonstrate the efficiency, enhanced stability, and accuracy of the proposed AAROC method. △ Less

Submitted 2 December, 2024; originally announced December 2024.

Comments: 25 pages, 10 figures