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arXiv 2024年

作者： Upreti, Dinesh Basnet, Rabindra Sharma, M.M. Chhetri, Santosh Karki Acharya, Gokul Nabi, Md Rafique Un Sakon, Josh Mortazavi, Mansour Hu, Jin Department of Physics University of Arkansas FayettevilleAR72701 United States Department of Chemistry & Physics University of Arkansas at Pine Bluff Pine BluffAR71603 United States MonArk NSF Quantum Foundry University of Arkansas FayettevilleAR72701 United States Department of Chemistry & Biochemistry University of Arkansas FayettevilleAR72701 United States Materials Science and Engineering Program Institute for Nanoscience and Engineering University of Arkansas FayettevilleAR72701 United States

engineering magnetism in layered magnets could result in novel phenomena related to two-dimensional (2D) magnetism, which can be useful for fundamental research and practical applications. Extensive doping efforts such as substitution and intercalation have been adopted to tune antiferromagnetic (AFM) properties in M2P2X6 compounds. The substitutional doping in this material family has mainly focused on bimetallic substitution. Recently, the metal substitution can also be extended to more than two metal elements, leading to medium and high-entropy alloys (MEAs and HEAs), which are fairly underexplored in layered magnetic systems including M2P2X6. In this work, we explored the magnetic properties of the previously unreported Cu- and Cr-substituted Ni2P2S6 i.e., CuxNi2(1-x)CrxP2S6. Our study reveals a relatively systematic evolution of AFM phases with substitution than that observed in traditional bimetallic substitution in M2P2X6. Furthermore, the Cu and Cr substitutions in Ni2P2S6 are found to enhance the ferromagnetic (FM) correlation, which is also accompanied by a possible weak FM phase at low temperatures for the intermediate compositions 0.32≤x≤0.80. Our work provides a strategy to establish ferromagnetism in AFM M2P2X6 that can also be used for property tuning in other layered magnets. © 2024, CC BY-NC-SA.

关键词： Ferromagnetism

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APPLICATION OF THE DIGITAL ANNEALER UNIT IN OPTIMIZING CHEMICAL REACTION CONDITIONS FOR ENHANCED PRODUCTION YIELDS

arXiv

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arXiv 2024年

作者： Li, Shih-Cheng Wang, Pei-Hwa Su, Jheng-Wei Chiang, Wei-Yin Huang, Shih-Hsien Lin, Yen-Chu Ou, Chia-Ho Chen, Chih-Yu Insilico Medicine Taiwan Ltd. Taipei City110208 Taiwan Department of Chemical Engineering Massachusetts Institute of Technology CambridgeMA02139 United States Quantum Information Center Chung Yuan Christian University Taoyuan City320314 Taiwan Master Program in Intelligent Computing and Big Data Chung Yuan Christian University Taoyuan City320314 Taiwan Department of Computer Science and Information Engineering National Pingtung University Pingtung City900392 Taiwan

Finding appropriate reaction conditions that yield high product rates in chemical synthesis is crucial for the chemical and pharmaceutical industries. However, due to the vast chemical space, conducting experiments for each possible reaction condition is impractical. Consequently, models such as QSAR (Quantitative Structure-Activity Relationship) or ML (Machine Learning) have been developed to predict the outcomes of reactions and illustrate how reaction conditions affect product yield. Despite these advancements, inferring all possible combinations remains computationally prohibitive when using a conventional CPU. In this work, we explore using a Digital Annealing Unit (DAU) to tackle these large-scale optimization problems more efficiently by solving Quadratic Unconstrained Binary Optimization (QUBO). Two types of QUBO models are constructed in this work: one using quantum annealing and the other using ML. Both models are built and tested on four high-throughput experimentation (HTE) datasets and selected Reaxys datasets. Our results suggest that the performance of models is comparable to classical ML methods (i.e., Random Forest and Multilayer Perceptron (MLP)), while the inference time of our models requires only seconds with a DAU. Additionally, in campaigns involving active learning and autonomous design of reaction conditions to achieve higher reaction yield, our model demonstrates significant improvements by adding new data, showing promise of adopting our method in the iterative nature of such problem settings. Our method can also accelerate the screening of billions of reaction conditions, achieving speeds millions of times faster than traditional computing units in identifying superior conditions. Therefore, leveraging the DAU with our developed QUBO models has the potential to be a valuable tool for innovative chemical synthesis. Copyright © 2024, The Authors. All rights reserved.

关键词： Machine learning

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Raman Linewidth Contributions from Four-Phonon and Electron-Phonon Interactions in Graphene

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Physical Review Letters 2022年第4期128卷 045901-045901页

作者： Zherui Han Xiaolong Yang Sean E. Sullivan Tianli Feng Li Shi Wu Li Xiulin Ruan School of Mechanical Engineering and the Birck Nanotechnology Center Purdue University West Lafayette Indiana 47907-2088 USA Institute for Advanced Study Shenzhen University Shenzhen 518060 China College of Physics and Center of Quantum Materials and Devices Chongqing University Chongqing 401331 China Materials Science and Engineering Program The University of Texas at Austin Austin Texas 78712 USA Department of Mechanical Engineering The University of Utah Salt Lake City Utah 84112 USA

The Raman peak position and linewidth provide insight into phonon anharmonicity and electron-phonon interactions in materials. For monolayer graphene, prior first-principles calculations have yielded decreasing linewidth with increasing temperature, which is opposite to measurement results. Here, we explicitly consider four-phonon anharmonicity, phonon renormalization, and electron-phonon coupling, and find all to be important to successfully explain both the G peak frequency shift and linewidths in our suspended graphene sample over a wide temperature range. Four-phonon scattering contributes a prominent linewidth that increases with temperature, while temperature dependence from electron-phonon interactions is found to be reversed above a doping threshold (ℏωG/2, with ωG being the frequency of the G phonon).

关键词： Lattice dynamics Phonons Graphene First-principles calculations Raman spectroscopy

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Axion dark matter search from terrestrial magnetic fields at extremely low frequencies

arXiv

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arXiv 2025年

作者： Nishizawa, Atsushi Taruya, Atsushi Himemoto, Yoshiaki Physics Program Graduate School of Advanced Science and Engineering Hiroshima University Hiroshima Higashi-Hiroshima739-8526 Japan Astrophysical Science Center Hiroshima University Hiroshima Higashi-Hiroshima739-8526 Japan Graduate School of Science The University of Tokyo Tokyo113-0033 Japan Center for Gravitational Physics and Quantum Information Yukawa Institute for Theoretical Physics Kyoto University Kyoto606-8502 Japan Chiba Kashiwa277-8583 Japan Department of Liberal Arts and Basic Sciences College of Industrial Technology Nihon University Chiba Narashino275-8576 Japan

The natural environment of the Earth can act as a sensitive detector for dark matter in ultralight axions. When axions with masses between 1 × 10−15 eV and 1 × 10−13 eV pass through the Earth, they interact with the global geomagnetic field, generating electromagnetic (EM) waves in the extremely low-frequency range (0.3–30 Hz) through axion-photon coupling. This paper is one of a series of companion papers for [1], focusing on the data analysis method and search results for an axion signal. Utilizing the theoretical predictions of axion-induced EM spectra from a companion study, we analyzed long-term observational data of terrestrial magnetic fields in this frequency band to search for axion-induced signals. Our analysis identified 65 persistent signal candidates with a signal-to-noise ratio (SNR) greater than 3. Aside from these candidates, we placed a new upper bound on the axion-photon coupling parameter, significantly refining the previous constraint from CAST by at most two orders of magnitude down to gaγ 4 × 10−13 GeV−1 for the axion mass around 3 × 10−14 eV. Copyright © 2025, The Authors. All rights reserved.

关键词： Spontaneous emission

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CubeSat single-photon detector module for investigating in-orbit laser annealing to heal radiation damage

arXiv

引用

arXiv 2024年

作者： Sultana, Nigar Krynski, Joanna Lim, Jin Gyu Floyd, John Lembeck, Michael Makarov, Vadim Kwiat, Paul Jennewein, Thomas Institute for Quantum Computing University of Waterloo WaterlooONN2L 3G1 Canada Department of Electrical and Computer Engineering University of Waterloo WaterlooONN2L 3G1 Canada Department of Physics and Astronomy University of Waterloo WaterlooONN2L 3G1 Canada University of Illinois Urbana-Champaign ChampaignIL United States Vigo Quantum Communication Center University of Vigo Vigo Spain Quantum Information Science Program Canadian Institute for Advanced Research TorontoONM5G 1Z8 Canada

Single-photon avalanche photodiodes (SPADs) based on silicon are widely considered for quantum satellite communications but suffer from an increasing dark count rate (DCR) due to displacement damage in their active areas induced by proton radiation. When the DCR of SPADs exceeds a certain threshold, they become unusable for quantum communication protocols. Previous laboratory experiments have demonstrated that laser annealing of SPADs’ active area with about 1 W optical power can significantly reduce radiation-induced DCR of synthetically irradiated SPADs. To assess the feasibility of in-orbit laser annealing on constantly irradiated SPADs in low-Earth orbit, we developed a module with a CubeSat form factor capable of both laser and thermal annealing of four silicon SPADs. Here we report the design and ground testing of this module, investigating laser annealing in a simulated space environment. Our results pave the way for an in-orbit trial that may prove this technology useful for future satellite missions with quantum receivers on board. Copyright © 2024, The Authors. All rights reserved.

关键词： Radiation damage

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On the X-ray efficiency of the white dwarf pulsar candidate ZTF J190132.9+145808.7

arXiv

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arXiv 2024年

作者： Bamba, Aya Terada, Yukikatsu Kashiyama, Kazumi Kisaka, Shota Minami, Takahiro Takahashi, Tadayuki Department of Physics Graduate School of Science The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-0033 Japan Research Center for the Early Universe School of Science The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-0033 Japan Trans-Scale Quantum Science Institute The University of Tokyo Tokyo113-0033 Japan Graduate School of Science and Engineering Saitama University 255 Shimo-Ohkubo Saitama Sakura338-8570 Japan Astronomical Institute Tohoku University Sendai980-8578 Japan Kavli Institute for the Physics and Mathematics of the Universe The University of Tokyo Kashiwa277-8583 Japan Physics Program Graduate School of Advanced Science and Engineering Hiroshima University Higashi-Hiroshima739-8526 Japan

Strongly magnetized, rapidly rotating massive white dwarfs (WDs) emerge as potential outcomes of double degenerate mergers. These WDs can act as sources of non-thermal emission and cosmic rays, gethering attention as WD pulsars. In this context, we studied the X-ray emissions from ZTF J190132.9+145808.7 (hereafter ZTF J1901+14), a notable massive isolated WD in the Galaxy, using the Chandra X-ray observatory. Our results showed 3.5σ level evidence of X-ray signals, although it is marginal. Under the assumption of a photon index of 2, we derived its intrinsic flux to be 2.3 (0.9–4.7) ×10−15 erg cm−2s−1 and luminosity 4.6 (2.0–9.5) ×1026 erg s−1 for a 0.5–7 keV band in the 90% confidence range, given its distance of 41 pc. We derived an X-ray efficiency (η) concerning the spin-down luminosity to be 0.012 (0.0022—0.074), a value comparable to that of ordinary neutron star pulsars. The inferred X-ray luminosity may be compatible with curvature radiation from sub-TeV electrons accelerated within open magnetic fields in the magnetosphere of ZTF J1901+14. Conducting more extensive X-ray observations is crucial to confirm whether ZTF J1901+14-like isolated WDs are also significant sources of X-rays and sub-TeV electron cosmic rays, similar to other WD pulsars in accreting systems. © 2024, CC BY-NC-ND.

关键词： White dwarfs

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Controlling and measuring a superposition of position and momentum

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Physical Review A 2023年第1期108卷 012215-012215页

作者： Takafumi Ono Nigam Samantarray John G. Rarity Quantum Engineering Technology Laboratories H. H. Wills Physics Laboratory and Department of Electrical & Electronic Engineering University of Bristol Bristol BS8 1FD United Kingdom Program in Advanced Materials Science Faculty of Engineering and Design Kagawa University 2217-20 Hayashi-cho Takamatsu Kagawa 761-0396 Japan JST PRESTO 4-1-8 Honcho Kawaguchi Saitama 332-0012 Japan Department of Physics University of Strathclyde John Anderson Building 107 Rottenrow Glasgow G4 0NG United Kingdom

We present an observation of quantum interference between position and momentum with photons. We prepared a superposition of position and momentum states by using slits, lenses, and an interferometer. The precise control and measuring of propagation time of the photon results in a clear quantum interference of 85% visibility. The generated quantum state is then used to verify the violation of particle propagation inequality proposed by Hofmann [Phys. Rev. A 96, 020101(R) (2017)], resulting in 5.9% below the statistically predicted lower bound. We believe that this result is a major step towards further developments in quantum theory, such as fundamental modifications to the interpretation of quantum mechanics.

关键词： quantum control quantum information theory quantum measurements quantum metrology

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Fate of multipolar physics in 5d2 double perovskites

arXiv

引用

arXiv 2023年

作者： Rayyan, Ahmed Liu, Xiaoyu Kee, Hae-Young Department of Physics University of Toronto TorontoONM5S 1A7 Canada Department of Materials Science and Engineering University of Washington SeattleWA98195 United States CIFAR Program in Quantum Materials Canadian Institute for Advanced Research TorontoONM5G 1M1 Canada

In a cubic environment, the ground state of spin-orbit coupled 5d2 ions is a non-Kramers Eg doublet, which hosts quadrupole and octupole moments. A series of 5d2 osmium double perovskites Ba2MOsO6 (M = Mg, Ca, Zn, Cd) have recently been proposed to exhibit multipolar orders. We investigate the structural properties of these materials using ab-initio calculations and find that the cubic structure is unstable for the Cd compound while the Mg, Ca, and Zn materials retain Fm3¯m symmetry. We show that Ba2CdOsO6 favours a rhombohedral R3¯ structure characterized by a−a−a− octahedral tiltings as indicated by unstable T1g phonon modes. Trigonal distortions split the excited T2g triplet into an Eg′ doublet and an Ag singlet, which may cross energy levels with the Eg doublet and suppress the multipolar physics. We find a window where Eg remains the lowest energy state under trigonal distortion, enabling the emergence of multipole phases in non-cubic crystal environments. © 2023, CC BY.

关键词： Barium compounds

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Lattice dynamics and in-plane antiferromagnetism in MnxZn1−xPS3 across the entire composition range

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Physical Review B 2023年第10期107卷 104415-104415页

作者： Robert Oliva Esther Ritov Faris Horani Iñigo Etxebarria Adam K. Budniak Yaron Amouyal Efrat Lifshitz Mael Guennou Department of Physics and Materials Science University of Luxembourg 41 rue du Brill L-4422 Belvaux Luxembourg Geosciences Barcelona (geo3bcn-CSIC) Lluis Sole I Sabaris S/N 08028 Barcelona Catalonia Spain Schulich Faculty of Chemistry Solid State Institute Russell Berrie Nanotechnology Institute Helen Diller Quantum Center Nancy and Stephen Grand Technion Energy Program Technion–Israel Institute of Technology Haifa 3200003 Israel Fisika Saila and EHU Quantum Center Euskal Herriko Unibertsitatea UPV/EHU Sarriena Auzoa z/g 48940 Leioa Basque Country Spain Department of Materials Science and Engineering Technion–Israel Institute of Technology Haifa 3200003 Israel

Alloyed MnxZn1−xPS3 samples have been grown covering the whole compositional range and studied by means of Raman spectroscopy at temperatures from 4 to 850 K. Our results, supported by superconducting quantum interference device magnetic measurements, allowed us, on one hand, to complete the magnetic phase diagram of MnxZn1−xPS3 and establish x≥0.3 as the composition at which the alloy retains antiferromagnetism and, on the other hand, to identify the Raman signatures indicative of a magnetic transition. The origin of these Raman signatures is discussed in terms of spin-phonon coupling, resulting in the appearance of low- and high-frequency phonon modes. For the alloy, an assignation of the first- and second-order modes is provided with the aid of first-principles lattice-dynamical calculations. The compositional dependence of all phonon modes is described, and the presence of zone-folded modes is shown to take place for the alloy. Finally, a comparison of the Raman spectra of ZnPS3 to other compounds of the transition metal phosphorus trisulfide family allowed us to conclude that low-frequency phonon peaks exhibit an abnormally large broadening. This is consistent with previous claims on the occurrence of a second-order Jahn-Teller effect that takes place for ZnPS3 and Zn-rich MnxZn1−xPS3.

关键词： Jahn-Teller effect Lattice dynamics Magnetic order Peierls transition Phonons Spin-phonon coupling 2-dimensional systems Crystal structures Density functional calculations Raman spectroscopy X-ray diffraction

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Optical conductivity of the Majorana mode at the s- and d-wave topological superconductor edge

arXiv

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arXiv 2024年

作者： Kamra, Lina Johnsen Lu, Bo Linder, Jacob Tanaka, Yukio Nagaosa, Naoto Center for Quantum Spintronics Department of Physics Norwegian University of Science and Technology TrondheimNO-7491 Norway Departamento de Física Téorica de la Materia Condensada Universidad Autónoma de Madrid MadridE-28049 Spain Department of Physics Massachusetts Institute of Technology CambridgeMA02139 United States Center for Joint Quantum Studies Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology Department of Physics Tianjin University Tianjin300354 China Department of Applied Physics Nagoya University Nagoya464-8603 Japan Research Center for Crystalline Materials Engineering Nagoya University Nagoya464-8603 Japan Saitama Wako351-0198 Japan Fundamental Quantum Science Program TRIP Headquarters RIKEN Wako351-0198 Japan

The Majorana fermion offers fascinating possibilities such as non-Abelian statistics and non-local robust qubits, and hunting it is one of the most important topics in current condensed matter physics. Most of the efforts have been focused on the Majorana bound state at zero energy in terms of scanning tunneling spectroscopy searching for the quantized conductance. On the other hand, a chiral Majorana edge channel appears at the surface of a three-dimensional topological insulator when engineering an interface between proximityinduced superconductivity and ferromagnetism. Recent advances in microwave spectroscopy of topological edge states open a new avenue for observing signatures of such Majorana edge states through the local optical conductivity. As a guide to future experiments, we show how the local optical conductivity and density of states present distinct qualitative features depending on the symmetry of the superconductivity, that can be tuned via the magnetization and temperature. In particular, the presence of the Majorana edge state leads to a characteristic non-monotonic temperature dependence achieved by tuning the magnetization. Copyright © 2024, The Authors. All rights reserved.

关键词： Topological insulators

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