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High-entropy magnetism of murunskite

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arXiv 2024年

作者： Tolj, D. Reddy, P. Živković, I. Akšamović, L. Soh, J.R. Komedera, K. Bialo, I. Kumar, C.M.N. Ivšić, T. Novak, M. Zaharko, O. Ritter, C. La Grange, T. Tabiś, W. Batistić, I. Forró, L. Rønnow, H.M. Sunko, D.K. Barišić, N. William H. Miller III Department of Physics and Astronomy Johns Hopkins University Baltimore United States Laboratory for Quantum Magnetism École Polytechnique Fédérale de Lausanne LausanneCH-1015 Switzerland Department of Physics Faculty of Science University of Zagreb Croatia Institute of Solid State Physics TU Wien Vienna1040 Austria Agency for Science Technology and Research Singapore138634 Singapore AGH University of Krakow Faculty of Physics and Applied Computer Science Kraków30-059 Poland Mössbauer Spectroscopy Laboratory Institute of Technology University of the National Education Commission Kraków30-084 Poland Physik-Institut Universität Zürich ZürichCH-8057 Switzerland Institute of Nuclear Physics PAN Kraków31-342 Poland Department of Physical Chemistry Ruđer Bošković Institute Zagreb10000 Croatia Paul Scherrer Institut VilligenCH-5232 Switzerland Institut Laue-Langevin Grenoble38000 France Laboratory for Ultrafast Microscopy and Electron Scattering École Polytechnique Fédérale de Lausanne LausanneCH-1015 Switzerland Stavropoulos Center for Complex Quantum Matter University of Notre Dame United States

Murunskite (K2FeCu3S4) is a bridging compound between the only two known families of high-temperature superconductors. It is a semiconductor like the parent compounds of cuprates, yet isostructural to metallic iron-pnictides. Moreover, like both families, it has an antiferromagnetic (AF)-like response with an ordered phase occurring below ≈ 100 K. Through comprehensive neutron, Mössbauer, and XPS measurements on single crystals, we unveil AF with a nearly commensurate quarter-zone wave vector. Intriguingly, the only identifiable magnetic atoms, iron, are randomly distributed over one-quarter of available crystallographic sites in 2D planes, while the remaining sites are occupied by closed-shell copper. Notably, any interpretation in terms of a spin-density wave is challenging, in contrast to the metallic iron-pnictides where Fermi-surface nesting can occur. Our findings align with a disordered-alloy picture featuring magnetic interactions up to second neighbors. Moreover, in the paramagnetic state, iron ions are either in Fe3+ or Fe2+ oxidation states, associated with two distinct paramagnetic sites identified by Mössbauer spectroscopy. Upon decreasing the temperature below the appearance of magnetic interactions, these two signals merge completely into a third, implying an orbital transition. It completes the cascade of (local) transitions that transform iron atoms from fully orbitally and magnetically disordered to homogeneously ordered in inverse space, but still randomly distributed in real space. © 2024, CC BY.

关键词： Iron compounds

Quantum Random Access Codes Implementation for Resource Allocation and Coexistence with Classical Telecommunication

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arXiv 2024年

作者： Ribezzo, Domenico Salazar, Roberto Czartowski, Jakub Segur, Flora Lemmi, Gianmarco Petitjean, Antoine Farrugia, Noel Xuereb, André Bacco, Davide Zavatta, Alessandro Firenze50125 Italy Università degli Studi di Napoli Federico II Napoli Italy Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University Kraków30-348 Poland Doctoral School of Exact and Natural Sciences Jagiellonian University ul. L ojasiewicza 11 Kraków30-348 Poland Merqury Cybersecurity Limited Malta Department of Physics University of Malta MsidaMSD 2080 Malta Department of Physics and Astronomy University of Florence Sesto Fiorentino50019 Italy QTI S.r.l. Firenze50125 Italy

In a world where Quantum Networks are rapidly becoming a reality, the development of the Quantum Internet is gaining increasing interest. Nevertheless, modern quantum networks are still in the early stages of development and have limited capacity to distribute resources among different users – a constraint that needs to be taken into account. In this work we aim to investigate these constraints, using a novel setup for implementing Quantum Random Access Codes (QRACs), communication protocols known for their quantum advantage over their classical counterparts and semi- device-independent self-testing applications. Our QRAC states, made for the first time using weak coherent pulses instead of entangled single photons, allow us to experimentally test our encoding and decoding strategy from the resource allocation perspective. Moreover, by emulating a coexistent classical communication, we test the resilience of our implementation in presence of noise. The achieved results represent a significant milestone both for theoretical studies of quantum resource allocation and for the implementation of quantum infrastructures capable of coexisting with regular telecommunication networks. Copyright © 2024, The Authors. All rights reserved.

关键词： Resource allocation

Scalable method for Bayesian experimental design without integrating over posterior distribution

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arXiv 2023年

作者： Hoang, Vinh Espath, Luis Krumscheid, Sebastian Tempone, Raúl Mathematics for Uncertainty Quantification RWTH Aachen University Germany Faculty of Science University of Nottingham United Kingdom Steinbuch Center for Computing Institute for Applied and Numerical Mathematics Karlsruhe Institute of Technology Karlsruhe76131 Germany Computer Electrical and Mathematical Sciences and Engineering KAUST Alexander von Humboldt professor in Mathematics of Uncertainty Quantification RWTH Aachen University Germany

We address the computational efficiency in solving the A-optimal Bayesian design of experiments problems for which the observational map is based on partial differential equations and, consequently, is computationally expensive to evaluate. A-optimality is a widely used and easy-to-interpret criterion for Bayesian experimental design. This criterion seeks the optimal experimental design by minimizing the expected conditional variance, which is also known as the expected posterior variance. This study presents a novel likelihood-free approach to the A-optimal experimental design that does not require sampling or integrating the Bayesian posterior distribution. Our proposed approach is developed based on two properties of the conditional expectation: the law of total variance and the property of orthogonal projection. The expected conditional variance is obtained via the variance of the conditional expectation using the law of total variance, and we take advantage of the orthogonal projection property to approximate the conditional expectation. We derive an asymptotic error estimation for the proposed estimator of the expected conditional variance and show that the intractability of the posterior distribution does not affect the performance of our approach. We use an artificial neural network (ANN) to approximate the nonlinear conditional expectation in the implementation of our method. We then extend our approach for dealing with the case that the domain of experimental design parameters is continuous by integrating the training process of the ANN into minimizing the expected conditional variance. Specifically, we propose a nonlocal approximation of the conditional expectation and apply transfer learning to reduce the number of evaluations of the observation model. Through numerical experiments, we demonstrate that our method greatly reduces the number of observation model evaluations compared with widely used importance sampling-based approaches. This reduction is c

关键词： Design of experiments

Low mechanical loss and high refractive index in amorphous Ta2O5 films grown by magnetron sputtering

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Physical Review Materials 2024年第3期8卷 035603-035603页

作者： M. Molina-Ruiz K. Shukla A. Ananyeva G. Vajente M. R. Abernathy T. H. Metcalf X. Liu A. Markosyan R. Bassiri M. M. Fejer M. Fazio L. Yang C. S. Menoni F. Hellman Department of Physics University of California Berkeley Berkeley California 94720 USA Department of Materials Science and Engineering University of California Berkeley Berkeley California 94720 USA LIGO Laboratory California Institute of Technology Pasadena California 91125 USA Naval Research Laboratory Washington DC 20375 USA Edward L. Ginzton Laboratory Stanford University Stanford California 94305 USA Department of Applied Physics Stanford University Stanford California 94305 USA Department of Electrical and Computer Engineering Colorado State University Fort Collins Colorado 80523 USA Department of Chemistry Colorado State University Fort Collins Colorado 80523 USA

The ability to observe astronomical events through the detection of gravitational waves relies on the quality of multilayer coatings used on the optical mirrors of interferometers. Amorphous Ta2O5 (including TiO2:Ta2O5) currently limits detector sensitivity due to high mechanical loss. In this paper, mechanical loss measured at both cryogenic and room temperatures of amorphous Ta2O5 films grown by magnetron sputtering and annealed in air at 500 ∘C is shown to decrease for elevated growth temperature. Films grown at 310 ∘C and annealed yield a mechanical loss of 3.1×10−4 at room temperature, the lowest value reported for pure amorphous Ta2O5 grown by magnetron sputtering to date, and comparable to the lowest values obtained for films grown by ion beam sputtering. Additionally, the refractive index n increases 6% for elevated growth temperature, which could lead to improved sensitivity of gravitational-wave detectors by allowing a thickness reduction in the mirrors' coatings. Structural characterization suggests that the observed mechanical loss reduction in amorphous Ta2O5 films with increasing growth temperature correlates with a reduction in the coordination number between oxygen and tantalum atoms, consistent with TaOx polyhedra with increased corner-sharing and reduced edge- and face-sharing structures.

关键词： Structural properties Amorphous materials Film deposition Gravitational wave detectors Physical vapor deposition

Roadmap for phase change materials in photonics and beyond (vol 26, 107946, 2023)

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Iscience 2023年第12期26卷 107946页

作者： Prabhathan, Patinharekandy Sreekanth, Kandammathe Valiyaveedu Teng, Jinghua Ko, Joo Hwan Yoo, Young Jin Jeong, Hyeon-Ho Lee, Yubin Zhang, Shoujun Cao, Tun Popescu, Cosmin-Constantin Mills, Brian Gu, Tian Fang, Zhuoran Chen, Rui Tong, Hao Wang, Yi He, Qiang Lu, Yitao Liu, Zhiyuan Yu, Han Mandal, Avik Cui, Yihao Ansari, Abbas Sheikh Bhingardive, Viraj Kang, Myungkoo Lai, Choon Kong Merklein, Moritz Mueller, Maximilian J. Song, Young Min Tian, Zhen Hu, Juejun Losurdo, Maria Majumdar, Arka Miao, Xiangshui Chen, Xiao Gholipour, Behrad Richardson, Kathleen A. Eggleton, Benjamin J. Sharda, Kanudha Wuttig, Matthias Singh, Ranjan Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University 21 Nanyang Link Singapore 637371 Singapore Centre for Disruptive Photonic Technologies The Photonic Institute 50 Nanyang Avenue Singapore 639798 Singapore Institute of Materials Research and Engineering (IMRE) Agency for Science Technology and Research (A∗STAR) 2 Fusionopolis Way Innovis #08-03 Singapore 138634 Republic of Singapore School of Electrical Engineering and Computer Science Gwangju Institute of Science and Technology Gwangju 61005 Republic of Korea School of Materials Science and Engineering Gwangju Institute of Science and Technology Gwangju 61005 Republic of Korea DELL Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering Key Laboratory of Optoelectronic Information Technology (Ministry of Education of China) Tianjin University Tianjin 300072 China DELL School of Optoelectronic Engineering and Instrumentation Science Dalian University of Technology Dalian 116024 China Department of Materials Science &amp Engineering Massachusetts Institute of Technology Cambridge MA USA Materials Research Laboratory Massachusetts Institute of Technology Cambridge MA USA Department of Electrical &amp Computer Engineering University of Washington Washington Seattle USA Wuhan National Research Center for Optoelectronics School of Optical and Electronic Information Huazhong University of Science and Technology Wuhan China Institute of Advanced Materials Beijing Normal University Beijing 100875 China Nanoscale Optics Lab ECE Department University of Alberta Edmonton Canada CREOL College of Optics and Photonics University of Central Florida Orlando FL USA Institute of Photonics and Optical Science (IPOS) School of Physics The University of Sydney New South Wales NSW 2006 Australia The University of Sydney Nano Institute (Sydney Nano) The University of Sydney New South Wales NSW 2006 Australia Insti

Phase Change Materials (PCMs) have demonstrated tremendous potential as a platform for achieving diverse functionalities in active and reconfigurable micro-nanophotonic devices across the electromagnetic spectrum, ranging from terahertz to visible frequencies. This comprehensive roadmap reviews the material and device aspects of PCMs, and their diverse applications in active and reconfigurable micro-nanophotonic devices across the electromagnetic spectrum. It discusses various device configurations and optimization techniques, including deep learning-based metasurface design. The integration of PCMs with Photonic Integrated Circuits and advanced electric-driven PCMs are explored. PCMs hold great promise for multifunctional device development, including applications in non-volatile memory, optical data storage, photonics, energy harvesting, biomedical technology, neuromorphic computing, thermal management, and flexible electronics.

关键词： physics applied physics Materials application

Optimization of the performance parameters of the Giga passive optical networks for high transmission data rates with various modulation schemes

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Journal of Optical Communications 2024年第0期45卷 s941-s953页

作者： Khodaei, Amin Jahan, Kausar Babu, Gade Harish Ahammad, Shaik Hasane Sharma, Jyotsna Hossain, Md. Amzad Rashed, Ahmed Nabih Zaki Nabil, Ashraf Ali Faculty of Engineering Fiber Optics Research Centre Multimedia University Jalan Multimedia Cyberjaya63100 Malaysia Department of ECE Dadi Institute of Engineering and Technology Andhra Pradesh Anakapalle India Department of ECE CVR College of Engineering Hyderabad India Department of ECE Koneru Lakshmaiah Education Foundation Andhra Pradesh Vaddeswaram522302 India Department of Physics Amity School of Applied Sciences Amity University Manesar Haryana Gurugram122051 India Faculty of Electrical Engineering and Information Technology Institute of Theoretical Electrical Engineering Ruhr University Bochum Bochum44801 Germany Department of Electrical and Electronic Engineering Jashore University of Science and Technology Jashore7408 Bangladesh Electronics and Electrical Communications Engineering Department Faculty of Electronic Engineering Menoufia University Menouf32951 Egypt

This article has demonstrated the performance parameters optimization of the Giga passive optical networks (PONs) can enhanced with high transmission data rates with various modulation schemes. These modulation schemes are Mach-Zehnder modulator (MZM), electroabsorption modulator (EAM), amplitude modulator (AM), dual drive MZM measured (DDMZMM), electroabsorption modulator measured (EAMM), and LiNb MZM. The network reach can be extended to 30 km with 20 Gb/s. Maxi Q and mini bit error rate can be measured at both PIN and APD receivers. The study has emphasized AM modulation scheme is the best candidate modulation scheme for upgrading the network performance efficiency. LiNb MZM is the worst modulation scheme for the estimation of PONs performance. Optical power signals after fiber optic channel based different modulation schemes are clarified. EAM modulation scheme is the best technique for upgrading optical power signal through the network reach. © 2022 Walter de Gruyter GmbH, Berlin/Boston.

关键词： Passive optical networks

Thermodynamics of Black Holes with Rényi Entropy from Classical Gravity

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arXiv 2022年

作者： Nakarachinda, Ratchaphat Promsiri, Chatchai Tannukij, Lunchakorn Wongjun, Pitayuth Department of Mathematics and Computer Science Faculty of Science Chulalongkorn University Bangkok10330 Thailand Naresuan University 99 Moo 9 Tah Poe Mueang Phitsanulok Phitsanulok65000 Thailand Bangkok Thailand KMUTT Thailand Department of Physics School of Science King Mongkut’s Institute of Technology Ladkrabang 1 Chalong Krung 1 Alley Lat Krabang Bangkok10520 Thailand

The nonextensive nature of black holes is one of the most intriguing discoveries. In fact, the black hole entropy is a nonextensive quantity that scales by its surface area at the event horizon. In our work, we extend the thermodynamic phase space of black holes by treating the nonextensive parameter analyzed via the Rényi entropy as the thermodynamic variable. Using Euler’s theorem for a homogeneous function of the black holes’ mass, the compatible Smarr formula and the first law of black hole thermodynamics can be obtained. It is also demonstrated that, by keeping the same form of the black hole mass, the Rényi temperature is straightforwardly defined as proposed in the literature. Since many different types of black holes can indeed be successfully treated with such a procedure, our consideration is fairly general. It is worthwhile to argue that the black hole thermodynamics in Rényi statistics is rooted from the relation among geometric quantities in the same way as the standard approach corresponding to the Gibbs–Boltzmann statistics. Even though our results are based on classical gravity, they may pave the way to derive the Rényi temperature using the notion of quantum field in curved spacetime. © 2022, CC BY.

关键词： Black holes

Genetic Algorithms for Swarm UAV-Assisted Edge Content Delivery Optimisation Problem

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Genetic Algorithms for Swarm UAV-Assisted Edge Content Deliv...

IEEE International Conference on Research, Innovation and Vision for the Future

作者： Thuong C. Lam Nguyen-Son Vo Minh-Phung Bui De-Thu Huynh Thanh-Dung Tran Ha Duy Hung HUTECH Institute of Engineering HUTECH University Ho Chi Minh City Vietnam Institute of Fundamental and Applied Sciences Duy Tan University Ho Chi Minh City Vietnam Faculty of Information Technology School of Technology Van Lang University Ho Chi Minh City Vietnam School of Computer Science & Engineering The Saigon International University Ho Chi Minh City Vietnam Wireless Communications Research Group Faculty of Electrical and Electronics Engineering Ton Duc Thang University Ho Chi Minh City Vietnam

ISBN: (数字)9798331505073

ISBN: (纸本)9798331505080

Swarm unmanned aerial vehicles (UAV) have been increasingly studied for delivering the contents in 6G networks. In this paper, we propose an energy-aware capacity and trajectory (ECT) optimisation solution for swarm UAV-assisted edge content delivery networks (eCDN). The ECT optimisation solution enables a swarm UAV system to cooperatively fly 1) to the optimal set of stops and serve the user equipments in different clusters at maximum content delivery capacity and 2) in the optimal trajectory planning at minimum distance, under the constraint of energy resource. However, the ECT optimisation problem is challenging due to multiple objectives with respect to different optimisation variable types and complicated constraints. Genetic algorithms (GA) are therefore modified to address the challenge of solving the so-called multi-objective optimisation problem feasibly. Simulation results are shown to demonstrate the feasibility of GA and the benefits of ECT method for swarm UAV-assisted eCDN.

关键词： 6G mobile communication Trajectory planning Energy resources Content distribution networks Simulation Autonomous aerial vehicles Trajectory Time complexity Optimization Genetic algorithms

Gate simulation study of the 24-module J-PET scanner: Data analysis and image reconstruction

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Gate simulation study of the 24-module J-PET scanner: Data a...

作者： Dadgar, M. Kowalski, P. Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University Kraków30-348 Poland Department of Complex Systems National Centre for Nuclear Research Otwock-Świerk05-400 Poland

The Jagiellonian Positron Emission Tomograph (J-PET) is a novel PET device that, in contrast to commercial PET scanners, is based on plastic scintillator strips. Modular J-PET is the latest prototype that consists of 24 modules arranged in a cylinder. In this study, 6 point-like sources defined in the NEMA spatial resolution standard were simulated twice with total activities of 60 kBq and 60 MBq, respectively. Results of simulations were processed with the GOJA software and reconstructed with the QETIR package. © 2020 Jagellonian University. All rights reserved.

关键词： Image reconstruction