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arXiv 2025年

作者： Balgley, Jesse Park, Jinho Chu, Xuanjing Arnault, Ethan G. Gustafsson, Martin V. Ranzani, Leonardo Holbrook, Madisen Watanabe, Kenji Taniguchi, Takashi Perebeinos, Vasili Hone, James Fong, Kin Chung Department of Mechanical Engineering Columbia University New YorkNY10027 United States Department of Applied Physics and Mathematics Columbia University New YorkNY10027 United States Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA02139 United States RTX BBN Technologies Quantum Engineering and Computing Group CambridgeMA02138 United States Department of Physics Columbia University New YorkNY10027 United States National Institute for Materials Science 1-2-1 Sengen Ibaraki Tsukuba305-0044 Japan Department of Electrical Engineering University at Buffalo The State University of New York BuffaloNY14260 United States

The narrow bandgap of semiconductors allows for thick, uniform Josephson junction barriers, potentially enabling reproducible, stable, and compact superconducting qubits. We study vertically stacked van der Waals Josephson junctions with semiconducting weak links, whose crystalline structures and clean interfaces offer a promising platform for quantum devices. We observe robust Josephson coupling across 2–12 nm (3–18 atomic layers) of semiconducting WSe2 and, notably, a crossover from proximity- to tunneling-type behavior with increasing weak link thickness. Building on these results, we fabricate a prototype all-crystalline merged-element transmon qubit with transmon frequency and anharmonicity closely matching design parameters. We demonstrate dispersive coupling between this transmon and a microwave resonator, highlighting the potential of crystalline superconductor-semiconductor structures for compact, tailored superconducting quantum devices. Copyright © 2025, The Authors. All rights reserved.

关键词： Josephson junction devices

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Enhanced efficiency in bottom tunnel junction InGaN blue LEDs 25

Enhanced efficiency in bottom tunnel junction InGaN blue LED...

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Light-Emitting Devices, Materials, and Applications XXV 2021

作者： Van Deurzen, Len Bharadwaj, Shyam Lee, Kevin Protasenko, Vladimir Turski, Henryk Xing, Huili [Grace] Jena, Debdeep Department of Applied and Engineering Physics Cornell University IthacaNY14853 United States Department of Electrical and Computer Engineering Cornell University IthacaNY14853 United States Institute of High Pressure Physics Sokolowska 29/37 WarsawPL-01-142 Poland Department of Materials Science and Engineering Cornell University IthacaNY14853 United States

ISBN: (纸本)9781510642478

The physics of the bottom tunnel junction (BTJ) and its improvement over standard p-up geometry in InGaN blue LEDs is quantified through pulsed power measurements. It is found that the peak external quantum efficiency (EQE) and wall-plug efficiency (WPE) for a p-down BTJ LED is about threefold that of its counterpart, the p-up top tunnel junction (TTJ) LED. This is contributed to increased radiative recombination and reduced electron overflow. Further, the peaks occur at lower current densities for the BTJ device, suggesting earlier saturation of Shockley-Read-Hall traps. In the droop regime, where electron overflow, device heating, and 3-particle interactions are significant, the performance of the BTJ is found to be consistently better than that of the TTJ, converging at large current densities where the polarization fields are screened. © 2021 SPIE.

关键词： Tunnel junctions

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Distinguishing erbium dopants in Y2O3 by site symmetry: Ab initio theory of two spin-photon interfaces

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Physical Review Materials 2023年第12期7卷 126201-126201页

作者： Churna Bhandari Cüneyt Şahin Durga Paudyal Michael E. Flatté Ames National Laboratory Iowa State University Ames Iowa 50011 USA UNAM–National Nanotechnology Research Center and Institute of Materials Science and Nanotechnology Bilkent University Ankara Turkey Department of Physics and Astronomy University of Iowa Iowa City Iowa 52242 USA Department of Electrical and Computer Engineering Iowa State University Ames Iowa 50011 USA Department of Applied Physics Eindhoven University of Technology Eindhoven The Netherlands

We present a first-principles study of the defect formation and electronic structure of erbium (Er)–doped yttria (Y2O3). This is an emerging material for spin-photon interfaces in quantum information science due to the narrow-linewidth optical emission from Er dopants at standard telecommunication wavelengths and their potential for quantum memories and transducers. We calculate formation energies of neutral and negatively and positively charged Er dopants and find the charge-neutral configuration to be the most stable, consistent with experiment. Of the two substitutional sites of Er for Y, the C2 (more relevant for quantum memories) and C3i (more relevant for quantum transduction), we identify the former as possessing the lowest formation energy. The electronic properties are calculated using the Perdew-Burke-Ernzerhof functional along with the Hubbard U parameter and spin-orbit coupling, which yields a ∼6μB orbital and a ∼3μB spin magnetic moment, and 11 electrons in the Er 4f shell, confirming the formation of charge-neutral Er3+. This standard density functional theory approach underestimates the band gap of the host and lacks a first-principles justification for U. To overcome these issues we performed screened hybrid functional calculations, including a negative U for the 4f orbitals, with mixing (α) and screening (w) parameters. These produced robust electronic features with slight modifications in the band gap and the 4f splittings depending on the choice of tuning parameters. We also computed the many-particle electronic excitation energies and compared them with experimental values from photoluminescence.

关键词： First-principles calculations

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A Comprehensive Review on Big Data Challenges

A Comprehensive Review on Big Data Challenges

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Business Analytics for Technology and Security (ICBATS), International Conference on

作者： Salil Bharany Nasser Taleb M. Tariq Sadiq Nayab Kanwal Mohamed Abdelhakim Taher M. Ghazal Manas Pradhan Ateeq Ur Rehman CET Department Tech Amritsar India UK Faculty of Management Canadian University Dubai Dubai UAE School of Architecture Engineering University of Brighton School of Computer Science NCBA&E Lahore Pakistan Applied Science Research Center Applied Science Private University Amman Jordan College of Engineering and IT University of Dubai School of Information Technology Skyline University College Sharjah UAE

Increased hardware capability has allowed many businesses to store massive amounts of data in the previous few years. Streams of data may go on forever, so they are used in so many different applications. Analyzing and querying these streams is challenging for a stream of dynamic information. The term "big data" refers to a collection of methods and tools that must be combined in novel ways to unearth the vast amounts of previously unseen information buried within vast, diverse, and intricate databases. There are several ways to obtain, organize and analyze data in the big data world. In order to deal with streaming data, efficient data mining procedures must be in place. In this article, we examine a variety of Big Data-related concerns and challenges. This paper introduces the features, and challenges of managing big data.

关键词： Planets Transforms Big Data Media Telecommunications Security Surges

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Exciton-Exciton Interactions in Van der Waals Heterobilayers

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Physical Review X 2024年第3期14卷 031025-031025页

作者： Alexander Steinhoff Edith Wietek Matthias Florian Tommy Schulz Takashi Taniguchi Kenji Watanabe Shen Zhao Alexander Högele Frank Jahnke Alexey Chernikov Institut für Theoretische Physik Bremen Center for Computational Materials Science Institute of Applied Physics and Würzburg-Dresden Cluster of Excellence ct.qmat Department of Electrical Engineering and Computer Science Research Center for Materials Nanoarchitectonics Research Center for Electronic and Optical Materials Fakultät für Physik Munich Quantum Center and Center for NanoScience (CeNS) Munich Center for Quantum Science and Technology (MCQST) 80799 München Germany

Exciton-exciton interactions are key to understanding nonlinear optical and transport phenomena in van der Waals heterobilayers, which emerged as versatile platforms to study correlated electronic states. We present a combined theory-experiment study of excitonic many-body effects based on first-principle band structures and Coulomb interaction matrix elements. Key to our approach is the explicit treatment of the fermionic substructure of excitons and dynamical screening effects for density-induced energy renormalization and dissipation. We demonstrate that dipolar blueshifts are almost perfectly compensated by many-body effects, mainly by screening-induced self-energy corrections. Moreover, we identify a crossover between attractive and repulsive behavior at elevated exciton densities. Theoretical findings are supported by experimental studies of spectrally narrow, mobile interlayer excitons in atomically reconstructed, h-BN-encapsulated MoSe2/WSe2 heterobilayers. Both theory and experiment show energy renormalization on a scale of a few meV even for high injection densities in the vicinity of the Mott transition. Our results revise the established picture of dipolar repulsion dominating exciton-exciton interactions in van der Waals heterostructures and open up opportunities for their external design.

关键词： Excitons First-principles calculations Luminescence 2-dimensional systems Quantum many-body systems Many-body techniques

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Mimicking synaptic plasticity with wedged Pt/Co/Pt spin-orbit torque device

arXiv

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arXiv 2024年

作者： Chen, Shiwei Mishra, Rahul Chen, Huanjian Yang, Hyunsoo Qiu, Xuepeng Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology School of Physics Science and Engineering Tongji University Shanghai200092 China Department of Electrical and Computer Engineering National University of Singapore 117576 Singapore Centre for Applied Research in Electronics Indian Institute of Technology Delhi New Delhi110016 India

We fabricated a wedge shape of Pt/Co/Pt device with perpendicular magnetic anisotropy and manifested that the Co magnetization can be solely switched by spin-orbit torque without any magnetic field. Similar to the synaptic weight, we observed that the state of Co magnetization (presented by the anomalous Hall resistance RH) of wedged Pt/Co/Pt device can be tuned continuously with a large number of nonvolatile levels by applied pulse currents. Furthermore, we have studied the synaptic plasticity of wedged Pt/Co/Pt device, including the excitatory postsynaptic potentials (EPSP) or inhibitory postsynaptic potentials (IPSP) and spiking-time-dependent plasticity (STDP). The work elucidates the promise of wedged Pt/Co/Pt device as a candidate for new type of artificial synaptic devices induced by spin current and paving a substantial pathway towards the combination of spintronics and synaptic devices. Copyright © 2024, The Authors. All rights reserved.

关键词： Magnetic anisotropy

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Secrecy Outage Probability of Full-Duplex Relaying Vehicular Networks

Secrecy Outage Probability of Full-Duplex Relaying Vehicular...

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Japan-Egypt International Conference on Electronics, Communications and computers (JEC-ECC)

作者： Mohamed G. Abd El Ghafour Ahmed H. Abd El-Malek Ola E. Hassan Mohammed Abo-Zahhad Department of Engineering Mathematics and Physics Faculty of Engineering Alexandria University Alexandria Egypt School of Electronics Communications & Computer Engineering Egypt-Japan University of Science & Technology Alexandria Egypt Basic and Applied Science Department Arab Academy For Science Technology & Maritime Transport Smart Village Campus Giza Egypt Electrical Engineering Department Faculty of Engineering Assiut University Assiut Egypt

ISBN: (纸本)9781665464642

This paper investigates the secrecy performance of full-duplex cooperative vehicular relaying networks under passive eavesdropping attacks in the presence of co-channel interference. In the considered system model, a static source communicates with a static destination through a mobile full-duplex relay in the presence of a mobile passive eavesdropper and a static co-channel interferer. A closed-form expression for the exact secrecy outage probability of the system is derived for the Nakagami-m fading environment. Hence, the asymptotic secrecy outage probability is obtained at high signal-to-noise values. Numerical and Simulation results are obtained to validate the derived analytical expressions.

关键词： Fading channels Wireless communication Closed-form solutions Interference cancellation Simulation Full-duplex system Probability

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Atom Search Optimization with the Deep Transfer Learning-Driven Esophageal Cancer Classification Model

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Computational Intelligence and Neuroscience 2022年 2022卷 4629178页

作者： Alharbe, Nawaf R. Munshi, Raafat M. Khayyat, Manal M. Khayyat, Mashael M. Abdalaha Hamza, Saadia Hassan Aljohani, Abeer A. Applied College Taibah University Medina Saudi Arabia Faculty of Applied Medical Sciences King Abdulaziz University Rabigh Saudi Arabia Department of Information Systems College of Computers and Information Systems Umm Al-Qura University Makkah Saudi Arabia Department of Information Systems and Technology Faculty of Computer Science and Engineering University of Jeddah Jeddah Saudi Arabia Department of Computer Science College of Science and Humanities in Al-Sulail Prince Sattam Bin Abdulaziz University Saudi Arabia

Esophageal cancer (EC) is a commonly occurring malignant tumor that significantly affects human health. Earlier recognition and classification of EC or premalignant lesions can result in highly effective targeted intervention. Accurate detection and classification of distinct stages of EC provide effective precision therapy planning and improve the 5-year survival rate. Automated recognition of EC can aid physicians in improving diagnostic performance and accuracy. However, the classification of EC is challenging due to identical endoscopic features, like mucosal erosion, hyperemia, and roughness. The recent developments of deep learning (DL) and computer-aided diagnosis (CAD) models have been useful for designing accurate EC classification models. In this aspect, this study develops an atom search optimization with a deep transfer learning-driven EC classification (ASODTL-ECC) model. The presented ASODTL-ECC model mainly examines the medical images for the existence of EC in a timely and accurate manner. To do so, the presented ASODTL-ECC model employs Gaussian filtering (GF) as a preprocessing stage to enhance image quality. In addition, the deep convolution neural network- (DCNN-) based residual network (ResNet) model is applied as a feature extraction approach. Besides, ASO with an extreme learning machine (ELM) model is utilized for identifying the presence of EC, showing the novelty of the work. The performance of the ASODTL-ECC model is assessed and compared with existing models under several medical images. The experimental results pointed out the improved performance of the ASODTL-ECC model over recent approaches. © 2022 Nawaf R. Alharbe et al.

关键词： Diseases

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Data Dams: A Novel Framework for Regulating and Managing Data Flow in Large-Scale Systems

arXiv

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arXiv 2025年

作者： Bouke, Mohamed Aly Abdullah, Azizol Cengiz, Korhan Ivković, Nikola Mihaljević, Ivan Mohamud, Mudathir Ahmed Kowrina, Ahmed Department of Communication Technology and Network Faculty of Computer Science and Information Technology Universiti Putra Malaysia Serdang43400 Malaysia Department of Electrical-Electronics Engineering Biruni University Istanbul Turkey Faculty of Organization and Informatics University of Zagreb Pavlinska 2 Varaždin42000 Croatia Faculty of Computing SIMAD University Mogadishu252 Somalia Department of Computer Science Faculty of Computer Science and Information Technology Universiti Putra Malaysia Selangor Serdang43400 Malaysia Département d’Informatique et Mathématiques Faculté des Sciences et Techniques Université de Nouakchott Al Aasriya Nouakchott880 Mauritania

In the era of big data, managing dynamic data flows efficiently is crucial as traditional storage models struggle with real-time regulation and risk overflow. This paper introduces Data Dams, a novel framework designed to optimize data inflow, storage, and outflow by dynamically adjusting flow rates to prevent congestion while maximizing resource utilization. Inspired by physical dam mechanisms, the framework employs intelligent sluice controls and predictive analytics to regulate data flow based on system conditions such as bandwidth availability, processing capacity, and security constraints. Simulation results demonstrate that the Data Dam significantly reduces average storage levels (371.68 vs. 426.27 units) and increases total outflow (7999.99 vs. 7748.76 units) compared to static baseline models. By ensuring stable and adaptive outflow rates under fluctuating data loads, this approach enhances system efficiency, mitigates overflow risks, and outperforms existing static flow control strategies. The proposed framework presents a scalable solution for dynamic data management in large-scale distributed systems, paving the way for more resilient and efficient real-time processing architectures. © 2025, CC BY.

关键词： Queueing theory

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Automating the Practice of science – Opportunities, Challenges, and Implications

arXiv

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arXiv 2024年

作者： Musslick, Sebastian Bartlett, Laura K. Chandramouli, Suyog H. Dubova, Marina Gobet, Fernand Griffiths, Thomas L. Hullman, Jessica King, Ross D. Nathan Kutz, J. Lucas, Christopher G. Mahesh, Suhas Pestilli, Franco Sloman, Sabina J. Holmes, William R. Institute of Cognitive Science Osnabrück University Osnabrück49090 Germany Department of Cognitive Linguistic & Psychological Sciences Brown University ProvidenceRI02912 United States Centre for Philosophy of Natural and Social Science London School of Economics Lakatos Building Houghton Street LondonWC2A 2AE United Kingdom AaltoFI-00076 Finland Department of Computing Science University of Alberta 8900 114 St NW EdmontonABT6G 2S4 Canada Cognitive Science Program Indiana University 1101 E 10th St BloomingtonIN47405 United States School of Psychology University of Roehampton LondonSW15 4JD United Kingdom Departments of Psychology and Computer Science Princeton University PrincetonNJ United States Department of Computer Science Northwestern University IL United States Department of Chemical Engineering and Biotechnology University of Cambridge CambridgeCB3 0AS United Kingdom Department of Computer Science and Engineering Chalmers University of Technology Gothenburg412 96 Sweden Department of Applied Mathematics and Electrical and Computer Engineering University of Washington Seattle98195 United States School of Informatics University of Edinburgh 10 Crichton St. EH8 9AB United Kingdom Department of Materials Science and Engineering University of Toronto Canada Department of Psychology Department of Neuroscience The University of Texas AustinTX United States Department of Computer Science University of Manchester M13 9PL United Kingdom

Automation transformed various aspects of our human civilization, revolutionizing industries and streamlining processes. In the domain of scientific inquiry, automated approaches emerged as powerful tools, holding promise for accelerating discovery, enhancing reproducibility, and overcoming the traditional impediments to scientific progress. This article evaluates the scope of automation within scientific practice and assesses recent approaches. Furthermore, it discusses different perspectives to the following questions: Where do the greatest opportunities lie for automation in scientific practice?;What are the current bottlenecks of automating scientific practice?;and What are significant ethical and practical consequences of automating scientific practice? By discussing the motivations behind automated science, analyzing the hurdles encountered, and examining its implications, this article invites researchers, policymakers, and stakeholders to navigate the rapidly evolving frontier of automated scientific practice. © 2024, CC BY.

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