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Characterisation of Hβ spectra from EXO 051910+3737.7 X-rays binaries

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arXiv 2025年

作者： Nuchvanichakul, Pornisara Irawati, Puji Rittipruk, Pakakaew Gandhi, Poshak Knigge, Christian Charles, Phil Wannawichian, Suwicha M.S. Program in Applied Physics Department of Physics and Materials Science Faculty of Science Chiang Mai University Chiang Mai50200 Thailand Department of Physics and Astronomy University of Southampton Southampton United Kingdom National Astronomical Research Institute of Thailand Chiang Mai50180 Thailand Department of Physics and Materials Science Faculty of Science Chiang Mai University Chiang Mai50200 Thailand

We investigate the spectral characteristics of the Be/X-ray binary system, EXO 051910+3737.7, in which Be/X-ray systems are the largest sub-class of high-mass X-ray binaries. Spectroscopic observations are taken by the Thai National Telescope (TNT) with a Medium-RESolution spectrograph (MRES) instrument for seven nights spanning from 2020 to 2021. Our primary focus is directed towards the analysis of two Balmer lines, namely Hα and Hβ, given that Be stars typically exhibit emission features in at least one of these hydrogen Balmer lines during certain phases. Our observations reveal split Balmer emission lines throughout the entire duration of our monitoring. Double Gaussian profiles were employed for line fitting to characterize these lines. The presence of double peaks in the Balmer lines indicates the presence of asymmetries within the circumstellar disc. We then analyze V/R variations and the changes in Hβ spectra. Our analysis of V/R variation which Violet (V) and Red (R) peak intensity components, revealed rapid fluctuations occurring within a single day, although determining the precise periodicity was constrained by instrumental limitations and the duration of observability. Furthermore, employing observed the wavelength differences (∆λ) in conjunction with typical Be star parameters allowed us to estimate the radius (rβ) of the Hβ emitting envelope. The average value was calculated to be 2.585r∗, with a standard deviation of 0.050r∗ © 2025, CC BY-NC-ND.

关键词： Stars

Interference and Measurement: Obtaining information from the QAOA MaxCut state

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arXiv 2025年

作者： Agarwal, Pranjal Ali, Nada Hillery, Mark Department of Physics and Astronomy Hunter College The City University of New York 695 Park Avenue New YorkNY10065 United States Physics Program Graduate Center The City University of New York 365 Fifth Avenue New YorkNY10016 United States

In using the QAOA algorithm for the MaxCut problem one encodes the number of edges connecting the sets resulting from a partition of the vertices of a graph into phases of amplitudes of a quantum state (QAOA state). One wants to use the quantum state to find partitions with large numbers of edges connecting them. In the QAOA algorithm this is done by using a mixing operation and parameter optimization. Here we want to see what can be done if we only use simple aspects of quantum mechanics, interference and measurement, to extract information from the QAOA state. The idea is to use constructive interference to enhance the amplitudes corresponding to partitions with a large number of edges between the sets. We examine examples, but analytically and numerically. We also show how the results of sequences of measurements can be used to gain information about the landscape of solutions. Copyright © 2025, The Authors. All rights reserved.

关键词： Graph algorithms

Efficiently Cooling Quantum Systems with Finite Resources: Insights from Thermodynamic Geometry

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Physical Review Letters 2025年第7期134卷 070401-070401页

作者： Philip Taranto Patryk Lipka-Bartosik Nayeli A. Rodríguez-Briones Martí Perarnau-Llobet Nicolai Friis Marcus Huber Pharnam Bakhshinezhad Department of Physics and Astronomy University of Manchester Manchester M13 9PL United Kingdom Department of Physics Graduate School of Science The University of Tokyo 7-3-1 Hongo Bunkyo City Tokyo 113-0033 Japan Department of Applied Physics University of Geneva 1211 Geneva Switzerland Institute of Theoretical Physics Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University 30-348 Kraków Poland Atominstitut Technische Universität Wien Stadionallee 2 1020 Vienna Austria Miller Institute for Basic Research in Science University of California Berkeley California 94720 USA Física Teòrica: Informació i Fenòmens Quàntics Departament de Física Universitat Autònoma de Barcelona 08193 Bellatera (Barcelona) Spain Institute for Quantum Optics and Quantum Information—IQOQI Vienna Austrian Academy of Sciences Boltzmanngasse 3 1090 Vienna Austria

Landauer’s limit on heat dissipation during information erasure is critical as devices shrink, requiring optimal pure-state preparation to minimize errors. However, Nernst’s third law states this demands infinite resources in energy, time, or control complexity. We address the challenge of cooling quantum systems with finite resources. Using Markovian collision models, we explore resource trade-offs and present efficient cooling protocols (that are optimal for qubits) for coherent and incoherent control. Leveraging thermodynamic length, we derive bounds on heat dissipation for swap-based strategies and discuss the limitations of preparing pure states efficiently.

关键词： Cooling

A novel approach to data generation in generative model

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arXiv 2025年

作者： Kim, JaeHong Shim, Jaewon Healthcare Legal and Policy Center Graduate school of Law Korea University Seoul02841 Korea Republic of Human-Inspired AI Research Korea University Seoul02841 Korea Republic of Center for 0D Nanofluidics Institute of Applied Physics Department of Physics and Astronomy Seoul National University Seoul08826 Korea Republic of

Variational Autoencoders (VAEs) and other generative models are widely employed in artificial intelligence to synthesize new data. However, current approaches rely on Euclidean geometric assumptions and statistical approximations that fail to capture the structured and emergent nature of data generation. This paper introduces the Convergent Fusion Paradigm (CFP) theory, a novel geometric framework that redefines data generation by integrating dimensional expansion accompanied by qualitative transformation. By modifying the latent space geometry to interact with emergent high-dimensional structures, CFP theory addresses key challenges such as identifiability issues and unintended artifacts like hallucinations in Large Language Models (LLMs). CFP theory is based on two key conceptual hypotheses that redefine how generative models structure relationships between data and algorithms. Through the lens of CFP theory, we critically examine existing metric-learning approaches. CFP theory advances this perspective by introducing time-reversed metric embeddings and structural convergence mechanisms, leading to a novel geometric approach that better accounts for data generation as a structured epistemic process. Beyond its computational implications, CFP theory provides philosophical insights into the ontological underpinnings of data generation. By offering a systematic framework for high-dimensional learning dynamics, CFP theory contributes to establishing a theoretical foundation for understanding the data-relationship structures in AI. Finally, future research in CFP theory will be led to its implications for fully realizing qualitative transformations, introducing the potential of Hilbert space in generative *** Codes 00A30 (Primary), 68T99 (Secondary) © 2025, CC BY-NC-ND.

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Correlation between complex spin textures and the magnetocaloric and Hall effects in Eu(Ga1−xAlx)4 (x=0.9, 1)

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Physical Review B 2025年第16期111卷 165136-165136页

作者： Kelly J. Neubauer Kevin Allen Jaime M. Moya Mason L. Klemm Feng Ye Zachary Morgan Lisa DeBeer-Schmitt Wei Tian Emilia Morosan Pengcheng Dai Department of Physics and Astronomy Rice University Houston Texas 77005 USA Smalley-Curl Institute Rice University Houston Texas 77005 USA Rice Center for Quantum Materials Rice University Houston Texas 77005 USA Applied Physics Graduate Program Rice University Houston Texas 77005 USA Present address: Department of Chemistry Princeton University Princeton New Jersey 08544 USA. Neutron Scattering Division Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA

Determining the electronic phase diagram of a quantum material as a function of temperature (T) and applied magnetic field (H) forms the basis for understanding the microscopic origin of transport properties, such as the anomalous Hall effect (AHE) and topological Hall effect (THE). For many magnetic quantum materials, including EuAl4, a THE arises from a topologically protected magnetic skyrmion lattice with a nonzero scalar spin chirality. We identified a square skyrmion lattice (sSkL) peak in Eu(Ga1−xAlx)4 (x=0.9) identical to the peak previously observed in EuAl4 by performing neutron-scattering measurements throughout the phase diagram. Comparing these neutron results with transport measurements, we found that in both compounds the maximal THE does not correspond to the sSkL area. Instead of the maximal THE, the maximal magnetocaloric-effect boundaries better identify the sSkL lattice phase observed by neutron-scattering measurements. The maximal THE therefore arises from interactions of itinerant electrons with frustrated spin fluctuations in a topologically trivial magnetic state.

关键词： Hall effect

Disentangling the Effects of Temperature, Clouds, and Gravity on K I doublet in L dwarfs

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arXiv 2025年

作者： Baldelli, Alexandra J. Suárez, Genaro Cruz, Kelle L. Faherty, Jacqueline K. Rothermich, Austin Department of Astrophysics American Museum of Natural History Central Park West at 79th Street NY10024 United States Department of Applied Physics and Applied Mathematics Columbia University New YorkNY United States Department of Physics and Astronomy Hunter College City University of New York 695 Park Avenue New YorkNY10065 United States Department of Physics Graduate Center City University of New York 365 Fifth Avenue New YorkNY10016 United States

We investigate the effects of surface gravity, effective temperature, and cloudiness on the potassium doublet (K I) at 1.17 μm in brown dwarf spectra. Using pseudo-Voigt profiles to fit the K I doublet in Sonora Diamondback atmospheric model spectra, we find that gravity and cloudiness affect the spectra differently in mid to late-L dwarfs. The full-width at half-maximum (FWHM) is strongly correlated with surface gravity, while the maximum depth strongly correlates with cloudiness. This method allows us to separate the effects of clouds and surface gravity on the K I 1.17 μm doublet. We also find that the FWHM and maximum depth of the doublet can help to estimate the effective temperature and surface gravity in early to mid-L dwarfs. © 2025, CC BY.

关键词： Gravitational effects

Visualizing Field-free Deterministic Magnetic Switching of all–van der Waals Spin-Orbit Torque System Using Spin Ensembles in Hexagonal Boron Nitride

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arXiv 2025年

作者： Zhang, Xi Zhou, Jingcheng Hu, Chaowei Deng, Kuangyin Wang, Chuangtang Agarwal, Nishkarsh Jin, Hanshang Al-Matouq, Faris A. Xu, Stelo Trivedi, Roshan S. Li, Senlei Rathi, Sumedh Lu, Hanyi Jiang, Zhigang Taufour, Valentin Hovden, Robert Zhao, Liuyan Cheng, Ran Xu, Xiaodong Chu, Jiun-Haw Du, Chunhui Rita Wang, Hailong School of Physics Georgia Institute of Technology AtlantaGA30332 United States Department of Physics University of Washington SeattleWA98105 United States Department of Electrical and Computer Engineering University of California RiversideCA92521 United States Department of Physics University of Michigan Ann ArborMI48109 United States Department of Materials Science and Engineering University of Michigan Ann ArborMI48109 United States Department of Physics and Astronomy University of California DavisCA95616 United States Department of Physics University of California San Diego La Jolla CA92093 United States Applied Physics Program University of Michigan Ann ArborMI48109 United States Department of Physics and Astronomy University of California RiversideCA92521 United States Department of Materials Science and Engineering University of Washington SeattleWA98105 United States

Recently, optically active spin defects embedded in van der Waals (vdW) crystals have emerged as a transformative quantum sensing platform to explore cutting-edge materials science and quantum physics. Taking advantage of excellent solid-state integrability, this new class of spin defects can be arranged in controllable nanoscale proximity of target materials in vdW heterostructures, showing great promise for improving spatial resolution and field sensitivity of current sensing technologies. Building on this state-of-the-art measurement platform, here we report hexagonal boron nitride-based quantum imaging of field-free deterministic magnetic switching of room-temperature two-dimensional magnet Fe3GaTe2 in an all-vdW spin-orbit torque (SOT) system. By visualizing SOT-driven variations of nanoscale Fe3GaTe2 magnetic stray field profile under different conditions, we have revealed how the observed magnetic switching evolves from deterministic to indeterministic behavior due to the interplay between out-of-plane spins, in-plane spins and Joule heating. This understanding, which is otherwise difficult to access by conventional transport measurements, offers valuable insights on material design, testing, and evaluation of next-generation vdW spintronic devices. Copyright © 2025, The Authors. All rights reserved.

关键词： Van der Waals forces

Twist, splay, and uniform domains in ferroelectric nematic liquid crystals

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arXiv 2025年

作者： Lavrentovich, Maxim O. Kumari, Priyanka Lavrentovich, Oleg D. Department of Earth Environment and Physics Worcester State University WorcesterMA01602 United States Department of Physics & Astronomy University of Tennessee KnoxvilleTN37996 United States Advanced Materials and Liquid Crystal Institute Kent State University KentOH44240 United States Materials Science Graduate Program Kent State University KentOH44240 United States Department of Physics Kent State University KentOH44240 United States

The recently-discovered ferroelectric nematic (NF) liquid crystal presents a host of defect phenomena due to its unique polar nature and long-ranged electrostatic interactions. Like the solid state ferroelectrics, the depolarization field in the material favors a spontaneous spatial variation of the polarization P, manifesting in myriad ways including a twist in the bulk and different arrangements of alternating polarization domains. Unlike the solid-state ferroelectrics with a bulk crystalline structure, the configuration of the NF fluids is determined not only by the reduction of depolarization fields but also by the alignment of molecules at interfaces. In this work, we consider an NF confined to a thin cell, pre-patterned with various types of apolar surface anchoring produced by photoalignment. For uniform planar alignment, we find that the sample forms a series of striped domains. For a cell pre-patterned with a radial +1 defect pattern, the NF breaks up into "pie-slice" polarization domains. We calculate the elastic and electrostatic energy balance which determines the observed configurations and demonstrate that the electrostatic interactions tend to decrease the characteristic domain size λ while the elastic and surface anchoring interactions facilitate a larger λ. We also demonstrate that ionic screening mitigates electrostatic interactions, increasing λ and, above some critical concentration, eliminating the domains altogether. Copyright © 2025, The Authors. All rights reserved.

关键词： Depolarization

The effect of stereochemical constraints on the radius of gyration of folded proteins

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arXiv 2025年

作者： Logan, Jack A. Sumner, Jacob Grigas, Alex T. Shattuck, Mark D. O'Hern, Corey S. Department of Mechanical Engineering Yale University New HavenCT06520 United States Graduate Program in Computational Biology & Biomedical Informatics Yale University New HavenCT06520 United States Integrated Graduate Program in Physical and Engineering Biology Yale University New HavenCT06520 United States Benjamin Levich Institute and Physics Department The City College of New York New YorkNY10031 United States Department of Applied Physics Yale University New HavenCT06520 United States Department of Physics Yale University New HavenCT06520 United States

Proteins are composed of linear chains of amino acids that fold into complex three-dimensional structures. A general feature of folded proteins is that they are compact with a radius of gyration Rg(N) ∼ Nν that obeys power-law scaling with the number of amino acids N in each protein and ν ∼ 1/3. In this study, we investigate the internal scaling of the radius of gyration Rg(n) versus the chemical separation n between amino acids for all subchains of length n. We show that for globular proteins Rg(n) ∼ nν1,2 with a larger exponent ν1 > 1/3 for small n and a smaller exponent ν2 g(N) ∝ Nν. To describe this scaling behavior for Rg(n), we carry out folding simulations for a series of coarse-grained models for proteins beginning with the freely-jointed and freely-rotating chain models composed of spherical monomers and varying degrees of stereochemical constraints. We show that a minimal model, which coarse-grains amino acids into a single spherical backbone atom and one variable-sized spherical side-chain atom, and enforces bend- and dihedral-angle constraints, can recapitulate Rg(n) for x-ray crystal structures of globular proteins. In addition, this model predicts the correct average packing fraction and size of the hydrophobic core, which are two key physical features that can be used to distinguish between computational 'decoys' and correctly folded proteins in protein design applications. © 2025, CC BY.

关键词： Spheres