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arXiv 2024年

作者： Smith, Conor Chen, Yixiao Levy, Ryan Yang, Yubo Morales, Miguel A. Zhang, Shiwei Center for Computational Quantum Physics Flatiron Institute New YorkNY10010 United States Department of Electrical and Computer Engineering University of New Mexico AlbuquerqueNM87131 United States Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States

The two-dimensional electron gas (2DEG) is a fundamental model, which is drawing increasing interest because of recent advances in experimental and theoretical studies of 2D materials. Current understanding of the ground state of the 2DEG relies on quantum Monte Carlo calculations, based on variational comparisons of different ansatze for different phases. We use a single variational ansatz, a general backflow-type wave function using a message-passing neural quantum state architecture, for a unified description across the entire density range. The variational optimization consistently leads to lower ground-state energies than previous best results. Transition into a Wigner crystal (WC) phase occurs automatically at rs = 37±1, a density lower than currently believed. Between the liquid and WC phases, the same ansatz and variational search strongly suggest the existence of intermediate states in a broad range of densities, with enhanced short-range nematic spin correlations. Copyright © 2024, The Authors. All rights reserved.

关键词： Message passing

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Camera-based Motion Correction for PET/MR Brain Imaging

Camera-based Motion Correction for PET/MR Brain Imaging

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2022 IEEE Nuclear science Symposium, Medical Imaging Conference, and Room Temperature Semiconductor Detector Conference, IEEE NSS MIC RTSD 2022

作者： Fisher, Jonathan Groll, Andrew Kim, Chris C. Innes, Derek Levin, Craig S. Stanford University Department of Electrical Engineering CA United States Molecular Imaging Program Stanford University Department of Radiology CA United States Stanford University Department of Computer Science CA United States Stanford University Physics Electrical Engineering and Bioengineering Department of Radiology CA United States

ISBN: (纸本)9781665488723

In this work, we evaluated the performance of a camera-based rigid body motion correction solution in PET studies. We compared the image quality obtained by reconstructing a static phantom scan to those obtained by reconstructing a moving phantom scan with and without applying motion correction. Our suggested solution uses a camera to track a 3D marker attached to the object to be imaged (in this work, a resolution phantom). This data was incorporated in the multiple acquisition frames (MAF) image reconstruction algorithm to compensate for motion. While we got multiple spatially shifted replicas of the resolution phantom in the motion study's reconstructed image when motion correction was not applied, the motion-corrected image was comparable to the static image, with some degradation in spatial resolution (3.2-4.2 vs. 2.8-3.2 mm) and lower peak to valley ratio (indicating lower contrast to noise ratio). The context of the results presented is in PET/MR imaging, but in principle, this motion compensation method could be used in any type of medical imaging modality. © 2022 IEEE.

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Utilizing probabilistic entanglement between sensors in quantum networks

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Physical Review applied 2024年第6期22卷 064085-064085页

作者： Emily A. Van Milligen Christos N. Gagatsos Eneet Kaur Don Towsley Saikat Guha Department of Physics The University of Arizona 1630 East University Boulevard Tucson Arizona 85721 USA Department of Electrical and Computer Engineering The University of Arizona 1630 East University Boulevard Tucson Arizona 85721 USA Wyant College of Optical Sciences The University of Arizona 1630 East University Boulevard Tucson Arizona 85721 USA Program in Applied Mathematics The University of Arizona Tucson Arizona 85721 USA Cisco Quantum Lab Los Angeles USA College of Computer Science University of Massachusetts Amherst Massachusetts USA Department of Electrical and Computer Engineering The University of Maryland College Park Maryland 20742 USA

One of the most promising applications of quantum networks is entanglement-assisted sensing. The field of quantum metrology exploits quantum correlations to improve the precision bound for applications such as precision timekeeping, field sensing, and biological imaging. When measuring multiple spatially distributed parameters, current literature focuses on quantum entanglement in the discrete-variable case and quantum squeezing in the continuous-variable case, distributed amongst all of the sensors in a given network. However, it can be difficult to ensure that all sensors preshare entanglement of sufficiently high fidelity. This work probes the space between fully entangled and fully classical sensing networks by modeling a star network with probabilistic entanglement generation that is attempting to estimate the average of local parameters. The quantum Fisher information is used to determine which protocols best utilize entanglement as a resource for different network conditions. It is shown that without entanglement distillation there is a threshold fidelity below which classical sensing is preferable. For a network with a given number of sensors and links characterized by a certain initial fidelity and probability of success, this work outlines when and how to use entanglement, when to store it, and when it needs to be distilled.

关键词： Quantum entanglement

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Real-space and reciprocal-space topology in the Eu(Ga1−xAlx)4 square net system

arXiv

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arXiv 2023年

作者： Moya, Jaime M. Huang, Jianwei Lei, Shiming Allen, Kevin Gao, Yuxiang Sun, Yan Yi, Ming Morosan, E. Applied Physics Graduate Program Rice University HoustonTX77005 United States Department of Physics and Astronomy Rice University HoustonTX77005 United States Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences China

Magnetotransport measurements on the centrosymetric square-net Eu(Ga1−xAlx)4 compounds reveal evidence for both reciprocal- and real-space topology. For compositions 0.50 ≤ x ≤ 0.90, several intermediate field phases are found by magnetization measurements when H || c, where a maximum in the topological Hall effect (THE) is observed, pointing to the existence of topological (real-space topology) or non-coplanar spin textures. For 0.25 ≤ x ≤ 0.39, magnetization measurements reveal an intermediate field state, but no transition is visible in the Hall measurements. For x = 0.15, only one magnetic transition occurs below the Néel temperature TN, and no intermediate field spin reorientations are observed. The Hall effect varies smoothly before the spin-polarized (SP) state. However, in the SP state, Hall measurements reveal a large anomalous Hall effect (AHE) for all compositions, a consequence of reciprocal-space topology. Density functional theory calculations in the paramagnetic state indeed reveal a Dirac point that lies very near the Fermi energy, which is expected to split into Weyl nodes in the SP state, thereby explaining the observed AHE. These results suggest the Eu(Ga1−xAlx)4 family is a rare material platform where real- and reciprocal-space topology exist in a single material platform. © 2023, CC BY.

关键词： Topology

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Metallization of colloidal crystals

arXiv

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arXiv 2021年

作者： Ehlen, Ali Lopez-Rios, Hector de la Cruz, Monica Olvera Applied Physics Program Northwestern University Department of Materials Science and Engineering Northwestern University

Colloidal crystals formed by size-asymmetric binary particles co-assemble into a wide variety of colloidal compounds with lattices akin to ionic crystals. Recently, a transition from a compound phase with a sublattice of small particles to a metal-like phase in which the small particles are delocalized has been predicted computationally and observed experimentally. In this colloidal metallic phase, the small particles roam the crystal maintaining the integrity of the lattice of large particles, as electrons do in metals. A similar transition also occurs in superionic crystals, termed sublattice melting. Here, we use energetic principles and a generalized molecular dynamics (MD) model of a binary system of functionalized nanoparticles (NPs) to analyze the transition to sublattice delocalization in different co-assembled crystal phases as a function of temperature (T), number of grafted chains on the small particles, and number ratio between the small and large particles ns:nl. We find that ns:nl is the primary determinant of crystal type due to energetic interactions and interstitial site filling, while the number of grafted chains per small particle determines the stability of these crystals. We observe first-order sublattice delocalization transitions as T increases, in which the host lattice transforms from low- to high-symmetry crystal structures, including A20 → BCT → BCC, Ad → BCT → BCC, and BCC → BCC/FCC → FCC transitions and lattices. Analogous sublattice transitions driven primarily by lattice vibrations have been seen in some atomic materials exhibiting an insulator-metal transition also referred to as metallization. We also find minima in the lattice vibrations and diffusion coefficient of small particles as a function of ns:nl, indicating enhanced stability of certain crystal structures for ns:nl values that form compounds. © 2021, CC BY.

关键词： Molecular dynamics

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Oxygen-Incorporated Lithium-Rich Iron Sulfide Cathodes for Li-Ion Batteries with Boosted Material Stability and Electrochemical Performance

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Chemistry of Materials 2024年第19期36卷 9370-9379页

作者： Hailemariam, Adane G. Syum, Zeru Mamo, Tadios T. Qorbani, Mohammad Hsing, Cheng-Rong Sabbah, Amr Quadir, Shaham Bayikadi, Khasim S. Wu, Heng-Liang Wei, Ching-Ming Chen, Li-Chyong Chen, Kuei-Hsien Institute of Atomic and Molecular Sciences Academia Sinica Taipei10617 Taiwan Sustainable Chemical Science and Technology Taiwan International Graduate Program Academia Sinica Nangang Taipei11529 Taiwan Institute of Chemistry Academia Sinica Nangang Taipei11529 Taiwan Department of Applied Chemistry National Yang-Ming Chiao Tung University Hsinchu30010 Taiwan Department of Chemistry College of Natural Science Dire Dawa University Dire Dawa1362 Ethiopia Center of Atomic Initiative for New Materials National Taiwan University Taipei10617 Taiwan Department of Chemistry National Taiwan University Taipei10617 Taiwan Institute of Physics Academia Sinica Taipei11529 Taiwan Nano Science and Technology Taiwan International Graduate Program Academia Sinica Nangang Taipei11529 Taiwan Center for Condensed Matter Sciences National Taiwan University Taipei10617 Taiwan Division of Natural Science Center for General Education Chang Gung University Taoyuan City33302 Taiwan Tabbin Institute for Metallurgical Studies Tabbin Helwan 109 Cairo11421 Egypt GoldenCO80401 United States Department of Chemistry Northwestern University EvanstonIL60208 United States National Synchrotron Radiation Research Center Hsinchu30092 Taiwan Department of Physics National Taiwan University Taipei10617 Taiwan

Affordable and environmentally friendly electrode materials with multielectron redox reactions are imperative for the advancement of next-generation Li-ion batteries. In this context, the Li-rich layered iron sulfide cathode material (i.e., Li2FeS2) stands out as a promising candidate due to its unique multielectron cationic and anionic redox features. However, its practical application is hampered by inherent limitations in terms of poor structural stability and cycling performance. Herein, we conduct a systematic investigation into the impact of anionic substitution, where sulfur is partially replaced with oxygen, on the structural stability, intrinsic conductivity, and electrochemical properties of the Li2FeS2 cathode. First-principle calculations confirm that an optimum amount of oxygen incorporation is beneficial to stabilize the crystal structure and improve Li ion diffusion. Furthermore, cathodes with oxygen incorporation exhibit significant structural stability even when exposed to air for 24 h, demonstrating resistance against moisture. The Li2FeS1.8O0.2 cathode achieves a higher Coulombic efficiency of ∼100%, charge-discharge capacity of 310 mA h g-1 after 100 cycles, and a remarkable capacity recovery of around 94% following rate capability tests spanning 75 cycles. These findings introduce an innovative anion substitution approach for the development of Li-rich layered sulfide cathode materials, effectively mitigating structural deterioration. © 2024 American Chemical Society.

关键词： Cathodes

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To Sharpen or not to Sharpen? On the Effect of Sharpening Filters applied to Magnified Images 14

To Sharpen or not to Sharpen? On the Effect of Sharpening Fi...

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14th International Conference on Digital Image Processing, ICDIP 2022

作者： Emmendorfer, Leonardo R. de Olviveira, Vinicius Menezes Schein, Tatiana T. de Jesus, Junior C. Rodriguez, Bárbara D.A. Electrical Energy Processing Department Federal University of Santa Maria 97105-340 Brazil Center for Computational Science Federal University of Rio Grande 96201-900 Brazil Computational Modeling PhD Program Federal University of Rio Grande 96201-900 Brazil Computer Engineering Graduate Program Federal University of Rio Grande 96201-900 Brazil Institute of Mathematics Statistics and Physics Federal University of Rio Grande 96201-900 Brazil

ISBN: (纸本)9781510657564

Super-resolution algorithms aim to produce magnified high-resolution versions from low-resolution images. Some methods, however, are prone to generate blur during the process. Simple sharpening filters are adopted to alleviate this type of artifact. However, the actual effectiveness of this approach is not clear-cut in the literature. This work evaluates the effect of three simple sharpening filters on the quality of images obtained from super-resolution methods. Two metrics were considered in the evaluation: the Peak signal-to-noise ratio (PSNR) metric, and the Learned Perceptual Image Patch Similarity (LPIPS). One of the filters could consistently improve the LPIPS metric of magnified images from diverse benchmark sets on top of seven super-resolution methods. The increments obtained for the perceptual metric seem to occur due to the sharpening effect. Improvements on PSNR values were not as consistent. © 2022 SPIE.

关键词： Quality control

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Enhancement of Photocurrent Stability in Oxidation-Resistant WSe1.95Te0.05Nanosheets

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ACS Omega 2025年第24期10卷 26079-26089页

作者： Shiu-Ming Huang Ankush Saxena Pin-Cing Wang Tzu-Yueh Tu Ruei-San Chen Mitch M. C. Chou Department of Physics National Sun Yat-Sen University Kaohsiung 804 Taiwan (R.O.C.) Department of Physics National Sun Yat-Sen University Kaohsiung 804 Taiwan (R.O.C.)；Program on Key Materials Academy of Innovative Semiconductor and Sustainable Manufacturing National Cheng-Kung University Tainan 70101 Taiwan (R.O.C.) Graduate Institute of Applied Science and Technology National Taiwan University of Science and Technology Taipei 10607 Taiwan (R.O.C.) Program on Key Materials Academy of Innovative Semiconductor and Sustainable Manufacturing National Cheng-Kung University Tainan 70101 Taiwan (R.O.C.)

The electrical and optical characteristics of semimetallic WSe1.95Te0.05nanosheets have been comprehensively studied. The current–voltage measurements reveal a linear response when they are interfaced with platinum (Pt) electrodes, confirming the establishment of an ohmic contact between the WSe1.95Te0.05nanosheets and the Pt contacts. Additionally, the observed photocurrent demonstrates a direct linear correlation with the applied voltage and scales proportionally with the intensity of the incident light. Remarkably, the device achieves an exceptional photoresponsivity of 108 A/W at 0.5 V without requiring surface modifications. Furthermore, the electrical resistivity and photocurrent exhibit admirable stability, remaining unaffected by air exposure under ambient conditions for more than six months. These results underscore the inherent capabilities of WSe1.95Te0.05nanosheets and their potential as highly reliable materials for advanced photodetection applications.

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Prediction of Post-COVID-19 Pandemic Learning Mode Preferences Using Machine Learning

Prediction of Post-COVID-19 Pandemic Learning Mode Preferenc...

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International Conference on Computing and Networking Technology (ICCNT)

作者： Agus Pratondo Astri Novianty Budi Laksono Putro Siska Komala Sari Department of Multimedia Engineering School of Applied Sciences Telkom University Bandung Indonesia Department of Computer Engineering School of Electrical Engineering Telkom University Bandung Indonesia Department of Computer Science Education Indonesia University of Education Bandung Indonesia Diploma Program of Information System School of Applied System Telkom University Bandung Indonesia

The COVID-19 epidemic has had a huge impact on the educational landscape, prompting the adoption of online and remote learning as viable alternatives to conventional in-person instruction. In order to create effective educational methods as institutions prepare for the post-pandemic period, it is essential to understand students' preferences for various learning modes. With the aid of machine learning techniques, this study seeks to forecast preferences for learning styles in post-pandemic higher education. The study made use of a dataset compiled from a wide range of college students, which included information on the institution type (public or private), program type (bachelor's or diploma), academic discipline (science or humanities), gender, year of study, internet use, communication costs, comorbidity status, vaccination history, gadget and laptop ownership, and preferred learning mode (online, in-person, or both). For the aim of prediction, a Support Vector Machine (SVM) was used. Its kernel functions included linear, polynomial, radial basis function (RBF), and sigmoid. Performance criteria like accuracy, precision, recall, and F1 score were used to assess the models after the dataset was randomly partitioned into training and testing sets. The findings showed that for identifying the preferred mode of learning, SVM with the RBF kernel had the highest prediction accuracy (91.67%). Further proving the RBF kernel's efficacy, the confusion matrix analysis showed that high values in the diagonal represented accurate predictions for each of the three classes (both online and onsite). The results imply that machine learning approaches, in particular SVM with the RBF kernel, may accurately forecast students' preferences for learning modes in the post-pandemic situation. In a post-pandemic society, the findings provide insightful information that may be used to build adaptable and inclusive learning models and put them into practice.

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Investigating Cases and Clusters-Based Reuse Policies for Card-Playing Agents

Investigating Cases and Clusters-Based Reuse Policies for Ca...

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IEEE Symposium on Computational Intelligence and Games, CIG

作者： Gustavo B. Paulus Daniel P. Vargas Joaquim V. C. Assunção Luis A. L. Silva Federal Institute of Education Science and Technology of Rio Grande do Sul Ibirubá Brazil Graduate Program in Computer Science Federal University of Santa Maria Santa Maria Brazil Applied Computing Department Federal University of Santa Maria Santa Maria Brazil

computer games continue to present challenging experimental fields for developing Artificial Intelligence (AI) models. With Case-Based Reasoning and Clustering, this work proposes novel cases and clusters-based reuse criteria for implementing card-playing agents with diversified playing skills. Using the game of Truco, a common game in South America, we detail how game actions are reused from past cases selected as query answers for given game problems. In doing so, the majority rule, the probability-based lottery, the probability of victory, and the number of points won reuse policies are used to select a cluster of cases. Then these policies are also used to select game actions from the cases within the selected cluster. Investigating the combined exploration of reuse policies, experiments of different natures evaluate the performance of implemented Truco bots disputing matches against each other. Players in these tournaments are equipped with varied policies and use case bases constructed differently.

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