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Raman Signatures of Single Point Defects in Hexagonal Boron Nitride Quantum Emitters

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arXiv 2025年

作者： Cholsuk, Chanaprom Çakan, Aslı Deckert, Volker Suwanna, Sujin Vogl, Tobias Department of Computer Engineering TUM School of Computation Information and Technology Technical University of Munich Munich80333 Germany Munich80799 Germany Institute of Physical Chemistry Friedrich-Schiller University Jena07743 Germany Leibniz Institute of Photonic Technology Jena07745 Germany Abbe Center of Photonics Institute of Applied Physics Friedrich Schiller University Jena Jena07745 Germany Optical and Quantum Physics Laboratory Department of Physics Faculty of Science Mahidol University Bangkok10400 Thailand

Point defects in solid-state quantum systems are vital for enabling single-photon emission at specific wavelengths, making their precise identification essential for advancing applications in quantum technologies. However, pinpointing the microscopic origins of these defects remains a challenge. In this work, we propose Raman spectroscopy as a robust strategy for defect identification. Using density functional theory, we systematically characterize the Raman signatures of 100 defects in hexagonal boron nitride (hBN) spanning periodic groups III to VI, encompassing around 30,000 phonon modes. Our findings reveal that the local atomic environment plays a pivotal role in shaping the Raman lineshape, enabling the narrowing of potential defect candidates. Furthermore, we demonstrate that Raman spectroscopy can differentiate defects based on their spin and charge states as well as strain-induced variations, implying the versatility of this approach. Therefore, this study not only provides a comprehensive theoretical database of Raman spectra for hBN defects but also establishes a novel experiment framework for using tip-enhanced Raman spectroscopy to identify point defects. More broadly, our approach offers a universal method for defect identification in any quantum materials. Copyright © 2025, The Authors. All rights reserved.

关键词： Point defects

Channel nonlocality under decoherence

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arXiv 2024年

作者： Rico, Albert Morán, Moisés Bermejo Shahbeigi, Fereshte Życzkowski, Karol Faculty of Physics Astronomy and Applied Computer Science Institute of Theoretical Physics Jagiellonian University Kraków30-348 Poland Laboratoire d’Information Quantique Université libre de Bruxelles Belgium RCQI Institute of Physics Slovak Academy of Sciences Dúbravská cesta 9 Bratislava84511 Slovakia Center for Theoretical Physics Polish Academy of Science Warszawa02-668 Poland

The implementation of realistic quantum devices requires a solid understanding of the nonlocal resources present in quantum channels, and the effects of decoherence on them. Here we quantify nonlocality of bipartite quantum channels and identify its component resisting the effects of dephasing noise. Despite its classical nature, we demonstrate that the latter plays a relevant role in performing quantum protocols, such as state transformations and quantum coding for noisy communication. In the converse direction, we show that simulating certain stochastic processes with quantum channels undergoing decoherence has a communication advantage with respect to their classical simulation. Copyright © 2024, The Authors. All rights reserved.

关键词： Stochastic systems

Machine Learning based Beamwidth Adaptation for mmWave Vehicular Communications 16

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Machine Learning based Beamwidth Adaptation for mmWave Vehic...

16th IEEE Malaysia International Conference on Communication, MICC 2023

作者： Manic, Setinder Foh, Chuan Heng Kose, Abdulkadir Lee, Haeyoung Leow, Chee Yen Chatzimisios, Periklis Moessner, Klaus Suthaputchakun, Chakkaphong University of Surrey 5GIC & 6GIC Guildford United Kingdom Abdullah Gul University Department of Computer Engineering Kayseri Turkey School of Physics Engineering and Computer Science University of Hertfordshire Hatfield United Kingdom Universiti Teknologi Malaysia Wireless Communication Centre Johor Malaysia International Hellenic University Department of Information and Electronic Systems Engineering Thessaloniki Greece Technical University Faculty of Electronics and Information Technology Chemnitz Germany Bangkok University Electrical and Computer Engineering Department Khlong Nueng Thailand

ISBN: (纸本)9798350304343

The incorporation of mmWave technology in vehicular networks has unlocked a realm of possibilities, propelling the advancement of autonomous vehicles, enhancing interconnectedness, and facilitating communication for intelligent transportation systems (ITS). Despite these strides in connectivity, challenges such as high path-loss have arisen, impacting existing beam management procedures. This work aims to address this issue by improving beam management techniques, specifically focusing on enhancing the service time between vehicles and base stations through adaptive mmWave beamwidth adjustments, accomplished using a Contextual Multi-Armed Bandit Algorithm. By leveraging various conditions to train the ML agent of the Contextual Multi-Armed Bandit Algorithm, it seeks to learn about vehicle mobility profiles and optimize the usage of different antenna beamwidth settings to maximize seamless connection time. The extensive simulation results showcase the effectiveness of an adaptive beamwidth for mobility profiles, extending the connection time a vehicle experiences with a base station when compared to the existing strategies. © 2023 IEEE.

关键词： Base stations

Effect of Oxidation of Aged Power Transformer Insulating Oil on UV-Vis Spectra

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Effect of Oxidation of Aged Power Transformer Insulating Oil...

International Conference on Conduction and Breakdown in Dielectric Liquids

作者： Abdellatif K. Rashed Diaa-Eldin A. Mansour A. Rezk Mohsen Ghali Department of Electrical Power and Machines Engineering Faculty of Engineering Tanta University Tanta Egypt Department of Physics Faculty of Sciences Cantabria University Santander Spain Department of Electrical Power Engineering School of Electronics Communication and Computer Engineering Egypt-Japan University of Science and Technology Alexandria Egypt Department of Physics Institute of Basic and Applied Science Egypt-Japan University of Science and Technology Alexandria Egypt Physics Department Faculty of Science Kafrelsheikh University Kafrelsheikh Egypt

Optical spectroscopy is a major rising condition monitoring tool used to assess the status of the insulating oil in power transformer with a non-destructive approach. Accelerated thermal ageing studies have been discussed considering the effect of temperature on the oil condition. These studies didn't perfectly reflect what is happening in a real in-service power transformer due to the absence of copper catalyst in the ageing process. This paper discusses the effect of oxidation for a more precise simulation of the in-service ageing process of insulating oil. The optical results when copper catalyst is included in the accelerated thermal ageing process are compared with previously obtained results of accelerated thermal ageing to deduce the change that took place in the UV-Vis spectra. Dielectric dissipation factor is assessed to correlate between the optical spectra and transformer oil characteristic parameters. Dissolved decay products were calculated for the samples containing copper catalyst with the same ageing days compared to only thermally accelerated aged samples without the addition of copper catalyst. Dissolved decay products were correlated to both ageing days and dielectric dissipation factor. It was found that the copper catalyst caused a great difference in the obtained UV-Vis spectra.

关键词： Integrated optics Oils Catalysts Accelerated aging Oil insulation Oxidation Dielectrics

Certifying nonlocal properties of noisy quantum operations

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arXiv 2024年

作者： Rico, Albert Morán, Moisés Bermejo Shahbeigi, Fereshte Zyczkowski, Karol Faculty of Physics Astronomy and Applied Computer Science Institute of Theoretical Physics Jagiellonian University Kraków30-348 Poland Laboratoire d'Information Quantique Université libre de Bruxelles Belgium RCQI Institute of Physics Slovak Academy of Sciences Dúbravská cesta 9 Bratislava84511 Slovakia Center for Theoretical Physics Polish Academy of Science Warszawa02-668 Poland

We provide a unified framework to certify nonlocal properties of quantum channels from the correlations obtained in measurement protocols. Our approach gathers and extends fully- and semidevice independent methods for this purpose. We study the effect of different models of dephasing noise, some of which are shown to generate nonlocality and entanglement in special cases. In the extreme case of complete dephasing, the measurement protocols discussed yield particularly simple tests to certify nonlocality. These are based on the relations between bipartite quantum channels and their classical analogs: bipartite stochastic matrices defining conditional distributions. Copyright © 2024, The Authors. All rights reserved.

关键词： Stochastic systems

The LHCb VELO Upgrade Module Construction

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arXiv 2024年

作者： Akiba, K. Alexander, M. Bertella, C. Biolchini, A. Bitadze, A. Bogdanova, G. Borghi, S. Bowcock, T.J.V. Bridges, K. Brock, M. Burke, A.T. Buytaert, J. Byczynski, W. Carroll, J. Coco, V. Collins, P. Davis, A. Francisco, O. De Aguiar De Bruyn, K. De Capua, S. De Roo, K. Doherty, F. Douglas, L. Dufour, L. Dumps, R. Dutta, D. Eklund, L. Elvin, A. Farry, S. Prieto, A. Fernandez Lima, V. Franco Freestone, J. Fuzipeg, C. Galati, M.D. Torreira, A. Gallas Geertsema, R.E. Gersabeck, E. Gersabeck, M. Grant, F. Halewood-Leagas, T. Hennessy, K. Hulsbergen, W. Hutchcroft, D. Hynds, D. Jans, E. John, D. John, M. Jurik, N. Ketel, T. Klaver, S. Kopciewicz, P. Kostiuk, I. Kraan, M. Langstaff, M. Latham, T. Leflat, A. Cid, E. Lemos Lukashenko, V. Merk, M. Milovanovic, M. Monk, M. Murray, D. Nasteva, I. Oblakowska-Mucha, A. Pajero, T. Parkes, C. Alvarez, A. Pazos Trigo, E. Perez Perry, M. Reiss, F. Rinnert, K. Rodriguez, E. Rodriguez Rovekamp, J. Sanders, F. Smead, L.G. Scantlebury Schiller, M. Shears, T. Smith, N.A. Snoch, A. Švihra, P. Szumlak, T. van Beuzekom, M. van Overbeek, M. Regueiro, P. Vazquez Volkov, V. Wormald, M. Zunica, G. Rio de Janeiro Brazil Nikhef National Institute for Subatomic Physics Amsterdam Netherlands Nikhef National Institute for Subatomic Physics VU University Amsterdam Amsterdam Netherlands AGH - University of Science and Technology Faculty of Physics and Applied Computer Science Kraków Poland Affiliated with an institute covered by a cooperation agreement with CERN Switzerland Universidade de Santiago de Compostela Santiago de Compostela Spain Geneva Switzerland Department of Physics University of Warwick Coventry United Kingdom School of Physics and Astronomy University of Glasgow Glasgow United Kingdom Oliver Lodge Laboratory University of Liverpool Liverpool United Kingdom Department of Physics and Astronomy University of Manchester Manchester United Kingdom Department of Physics University of Oxford Oxford United Kingdom Van Swinderen Institute University of Groningen Groningen Netherlands Department of Physics and Astronomy Uppsala University Uppsala Sweden

The LHCb detector has undergone a major upgrade for LHC Run 3. This Upgrade I detector facilitates operation at higher luminosity and utilises full-detector information at the LHC collision rate, critically including the use of vertex information. A new vertex locator system, the VELO Upgrade, has been constructed. The core element of the new VELO are the double-sided pixelated hybrid silicon detector modules which operate in vacuum close to the LHC beam in a high radiation environment. The construction and quality assurance tests of these modules are described in this paper. The modules incorporate 200 µm thick, n-on-p silicon sensors bump-bonded to 130 nm technology ASICs. These are attached with high precision to a silicon microchannel substrate that uses evaporative CO2 cooling. The ASICs are controlled and read out with flexible printed circuits that are glued to the substrate and wire-bonded to the chips. The mechanical support of the module is given by a carbon fibre plate, two carbon fibre rods and an aluminium plate. The sensor attachment was achieved with an average precision of 21 µm, more than 99.5% of all pixels are fully functional, and a thermal figure of merit of 3 Kcm2W−1 was achieved. The production of the modules was successfully completed in 2021, with the final assembly and installation completed in time for data taking in 2022. © 2024, CC BY.

关键词： Substrates

First principles investigations of linear and nonlinear optical, radiation shielding and thermoelectric properties of the non-centrosymmetric Ba-based chalcogenides Ba2In2X5 (X=S, Te)

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Materials science in Semiconductor Processing 2025年 185卷

作者： Irfan, Muhammad Ibrahim, Fatma A. Hamdy, Mohamed S. Issa, Shams A.M. Zakaly, Hesham M.H. University of Lahore Sargodha Campus 40100 Pakistan Department of Chemistry College of Science King Khalid University Abha61413 Saudi Arabia King Khalid University P.O. Box 9004 Abha61413 Saudi Arabia Physics Department University of Tabuk Tabuk47512 Saudi Arabia Physics Department Faculty of Science Al-Azhar University Assiut Branch Assiut71524 Egypt Istinye University Faculty of Engineering and Natural Sciences Computer Engineering Department Istanbul34396 Turkey Institute of Physics and Technology Ural Federal University Yekaterinburg620002 Russia Department of Physics and Technical Sciences Western Caspian University Baku Azerbaijan

We explore the structural, elastic, optoelectronic, Radiation Shielding, and thermoelectric properties of Ba2In2X5 (X = S, Te) using first-principles computations and semi-classical Boltzmann Transport equations. These materials are classified as semiconductors exhibiting band gaps of 2.0 eV and 3.0 eV for both investigated NLO compounds that have more significant direct band gaps of superior optical birefringence and second-order NLO coefficients. The bonding properties have been investigated by analyzing the electron charge density (ECD) contour of the (1 0 1) crystallographic plane. It is clear from the reflectivity spectra that both compounds have a high degree of reflectivity, which could make them useful as UV and visible light shields. From 0 to 14.0 eV, the approximated reflectivity values, R (ω), are displayed against the incident photon energy. Therefore, the reflectivity is around 30 % before E ≈ 12.0 eV and 40 % reflection at ∼13.0 eV. Phase matching is possible for both compounds detected, as shown by the birefringence computations. Furthermore, the radiation shielding properties of Ba2In2S5 and Ba2In2Te5 have been evaluated using Phy-X software, demonstrating their potential effectiveness in medical and nuclear energy applications. The thermoelectric properties display N-type nature at low temperatures when the Seebeck coefficient changes from N to P-type at higher temperature ranges. These compounds have remarkable optical and thermal properties, rendering them highly attractive materials for thermoelectric and optoelectronic devices. © 2024 Elsevier Ltd

关键词： Birefringence

The construction and characterization of MgO transmission dynodes

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arXiv 2023年

作者： Chan, H.W. Prodanović, V. Theulings, A.M.M.G. Tao, S. Smedley, J. Hagen, C.W. Sarro, P.M. Graaf, H.V.D. Science Park 105 Amsterdam1098 XG Netherlands Faculty of Electrical Engineering Mathematics and Computer Science Department of Microelectronics ECTM Delft University of Technology Feldmannweg 17 Delft2628 CT Netherlands Faculty of Applied Sciences Department of Imaging Physics Delft University of Technology Lorentzweg 1 Delft2628 CJ Netherlands Department of Applied Physics Eindhoven University of Technology Eindhoven5600 MB Netherlands SLAC National Accelerator Laboratory Stanford University 2575 Sand Hill Road Menlo ParkCA94025 United States

In this work we demonstrate that ultra-thin (5 and 15 nm) MgO transmission dynodes with sufficient high transmission electron yield (TEY) can be constructed. These transmission dynodes act as electron amplification stages in a novel vacuum electron multiplier: the Timed Photon Counter. The ultra-thin membranes with a diameter of 30 µm are arranged in a square 64-by-64-array. The TEY was determined with a scanning electron microscope using primary electrons with primary energies of 0.75 - 5 keV. The method allows a TEY map of the surface to be made while simultaneously imaging the surface. The TEY of individual membranes can be extracted from the TEY map. An averaged maximum TEY of 4.6 ± 0.2 was achieved by using 1.35 keV primary electrons on a TiN/MgO bi-layer membrane with a layer thickness of 2 and 5 nm, respectively. The TiN/MgO membrane with a layer thickness of 2 and 15 nm, respectively, has a maximum TEY of 3.3 ± 0.1 (2.35 keV). Furthermore, the effect of the electric field strength on transmission (secondary) electron emission was investigated by placing the emission surface of a transmission dynode in close proximity to a planar collector. By increasing the electric potential between the transmission dynode and the collector, from -50 V to -100 V, the averaged maximum TEY improved from 4.6 ± 0.2 to 5.0 ± 0.3 at a primary energy of 1.35 keV with an upper limit of 5.5 on one of the membranes. Copyright © 2023, The Authors. All rights reserved.

关键词： Electrons

A complementary experimental study of epitaxial La0.67Sr0.33MnO3 to identify morphological and chemical disorder

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arXiv 2023年

作者： Verhage, Michael van der Minne, Emma Kiens, Ellen M. Korol, Lucas Spiteri, Raymond J. Koster, Gertjan Green, Robert J. Baeumer, Christoph Flipse, Kees Department of Applied Physics Eindhoven University of Technology Eindhoven Netherlands MESA+ Institute for Nanotechnology Faculty of Science and Technology University of Twente Enschede Netherlands Department of Physics & Engineering Physics University of Saskatchewan Saskatoon Canada Department of Computer Science University of Saskatchewan Saskatoon Canada Stewart Blusson Quantum Matter Institute University of British Columbia Vancouver Canada Peter Gruenberg Institute JARA-FIT Forschungszentrum Juelich GmbH Juelich Germany

Gaining insight into the characteristics of epitaxial complex oxide films is essential to control the behavior of devices and catalytic processes. It is known that substrate-induced strain, doping, and layer growth can affect the electronic and magnetic properties of the film’s bulk. In this study, we demonstrate a clear distinction between the bulk and surface of thin films of La0.67Sr0.33MnO3 in terms of chemical composition, electronic disorder, and surface morphology. We employed a combined experimental approach of X-ray based characterization methods and scanning probe microscopy. X-ray diffraction and resonant X-ray reflectivity revealed surface non-stochiometry in the strontium and lanthanum, as well as an accumulation of oxygen vacancies. Scanning tunneling microscopy showed a staggered growth surface morphology accompanied by an electronic phase separation (EPS) related to this non-stochiometry. The EPS is likely responsible for the temperature-dependent resistivity transition and is a cause of a proposed mixed-phase ferromagnetic and paramagnetic state near room temperature in these thin films. © 2023, CC BY.

关键词： Surface morphology