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

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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

Gravitational-wave constraints on scalar-tensor gravity from a neutron star and black-hole binary GW200115

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arXiv 2023年

作者： Takeda, Hiroki Tsujikawa, Shinji Nishizawa, Atsushi Department of Physics Kyoto University Kyoto606-8502 Japan Department of Physics Waseda University 3-4-1 Okubo Shinjuku Tokyo169-8555 Japan Physics Program Graduate School of Advanced Science and Engineering Hiroshima University Hiroshima Higashi-Hiroshima739-8526 Japan

In nonminimally coupled theories where a scalar field is coupled to the Ricci scalar, neutron stars (NSs) can have scalar charges through an interaction with matter mediated by gravity. On the other hand, the same theories do not give rise to hairy black hole (BH) solutions. The observations of gravitational waves (GWs) emitted from an inspiralling NS-BH binary system allows a possibility of constraining the NS scalar charge. Moreover, the nonminimally coupled scalar-tensor theories generate a breathing scalar mode besides two tensor polarizations. Using the GW200115 data of the coalescence of a BH-NS binary, we place observational constraints on the NS scalar charge as well as the nonminimal coupling strength for a subclass of massless Horndeski theories with a luminal GW propagation. Unlike past related works, we exploit a waveform for a mixture of tensor and scalar polarizations. Taking the breathing mode into account, the scalar charge is more tightly constrained in comparison to the analysis of the tensor GWs alone. In nonminimally coupled theories including Brans-Dicke gravity and spontaneous scalarization scenarios with/without a kinetic screening, we put new bounds on model parameters of each theory. Copyright © 2023, The Authors. All rights reserved.

关键词： Gravity waves

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基于合成磁场的声学非互易

science Bulletin 2023年第19期68卷 2164-2169,M0003页

作者：陈召宪李正伟翁经锴梁彬陆延青程建春 Andrea Alù Collaborative Innovation Center of Advanced Microstructures Key Laboratory of Modern Acoustics of Ministry of EducationInstitute of AcousticsDepartment of PhysicsNanjing UniversityNanjing 210093China College of Engineering and Applied Sciences Nanjing UniversityNanjing 210093China Photonics Initiative Advanced Science Research CenterCity University of New YorkNew York NY 10031USA Physics Program Graduate CenterCity University of New YorkNew York NY 10016USA

通过设计特定的时空调制,合成磁性的概念最近被提出以实现对光子和声子等电荷中性粒子的非互易操控,但现有方案存在着隔离度低、信号频率变化等问题.本文设计了一种新型耦合共振腔系统,其中动态耦合的相位作为实现声学合成磁场的新机制... 详细信息

通过设计特定的时空调制,合成磁性的概念最近被提出以实现对光子和声子等电荷中性粒子的非互易操控,但现有方案存在着隔离度低、信号频率变化等问题.本文设计了一种新型耦合共振腔系统,其中动态耦合的相位作为实现声学合成磁场的新机制并打破了系统的时间反演对称性,最终取得了优异的声波非互易传输.基于旋转波近似方法,作者严格推导出了实现系统强非互易声传输的参数条件.通过优化动态耦合之间的相位差以及耦合强度,实验展示了隔离度达45-dB和正向传输率达0.85的优异单向声传输.此外,这种单向声传输具有始末态频率不变和隔离方向可电控等重要特性.该研究突破了现有声波单向操控机制在效率和隔离度方面的局限,并为实现弗洛奎和非线性声学拓扑绝缘体提供了新途径.

关键词：隔离度信号频率动态耦合非线性声学拓扑绝缘体耦合共振耦合强度声传输

Three-level Λ-type microwave memory via parametric-modulation-induced transparency in a superconducting quantum circuit

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Physical Review Research 2023年第3期5卷 033192-033192页

作者： Kai-I Chu Wen-Te Liao Yung-Fu Chen Molecular Science and Technology Program Taiwan International Graduate Program Academia Sinica Taipei 11529 Taiwan Department of Physics National Central University Taoyuan City 32001 Taiwan Physics Division National Center for Theoretical Sciences Taipei 10617 Taiwan Center for Quantum Technology Hsinchu 30013 Taiwan Quantum Technology Center National Central University Taoyuan City 32001 Taiwan

We investigate theoretically a type of microwave memory that is composed of a single transmon qubit and a coupling resonator. The synergy of the parametric modulation of the qubit resonance frequency and a microwave directly driving the qubit transition can constitute effective three-level Λ-type electromagnetically induced transparency. We demonstrate that the dynamical control of such a parametric modulation allows for the possibility of microwave storage and retrieval using a single qubit. Our results pave the way towards the practical implementation of quantum information in superconducting circuits.

关键词： Electromagnetically induced transparency Quantum memories Quantum optics with artificial atoms Superconducting quantum optics Superconducting qubits

The third family quark mass hierarchy and FCNC in the universal seesaw model

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arXiv 2024年

作者： Morozumi, Takuya Panuluh, Albertus Hariwangsa Physics Program Graduate School of Advanced Science and Engineering Hiroshima University Higashi-Hiroshima739-8526 Japan Core of Research for the Energetic Universe Hiroshima University Hiroshima Higashi-Hiroshima739-8526 Japan Department of Physics Education Sanata Dharma University Paingan Maguwohardjo Sleman Yogyakarta55282 Indonesia

We present the study of the quark sector of the universal seesaw model with SU(2)L × SU(2)R × U(1)Y′ gauge symmetry in the massless case of the two lightest quark families. This model aims to explain the mass hierarchy of the third family quark by introducing a vector-like quark (VLQ) partner for each quark. In this model, we introduce SU(2)L and SU(2)R Higgs doublets. We derive explicitly the Lagrangian for the quark sector, Higgs sector, and kinetic terms of the gauge fields, starting from the Lagrangian, which is invariant under SU(2)L × SU(2)R × U(1)Y′ gauge symmetry. At each stage of the symmetry breaking, we present the Lagrangian with the remaining gauge symmetry. Additionally, we investigate the flavor-changing neutral currents (FCNCs) of Higgs (h) and Z-boson in the interaction with the top, heavy top, bottom, and heavy bottom quarks. © 2024, CC BY.

关键词： Elementary particles

Learning how to plan a science lesson: An exploration of preservice science teacher reflection in online microteaching

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Learning how to plan a science lesson: An exploration of pre...

National Seminar of physics Education 2021, SNPF 2021

作者： Haryanto, Z. Sulaeman, N.F. Nuryadin, A. Putra, P.D.A. Putri, S.A. Rahmawati, A.Z. Physics Education Study Program Faculty of Teacher Training and Education Mulawarman University Indonesia Graduate School of Sciences and Technology for Innovation Yamaguchi University Japan Science Education Study Program Faculty of Teacher Training and Education University of Jember Indonesia

As a compulsory approach in shaping pre-service teachers for Technological Pedagogical Content Knowledge (TPACK), microteaching is either essential and challenging. During the COVID-19 pandemic, the shift from offline to the online microteaching course had occurred. This major shift drives the change of planning science lessons. Our research examined how pre-service science teachers designed and reflected their planning on a 30-minute microteaching unit. The participants of our study were four groups of pre-service science teachers that consisted of five students. The participants were pre-service science teachers from two national universities in Indonesia that were chosen by purposive sampling. The data was collected through the lesson plan, self-reflection to the lesson plan, and group discussion. We conducted both qualitative and quantitative analysis on research data for content analysis. The qualitative analysis dealt with the themes and patterns of the theme, while quantitative analysis dealt with the duration and frequency of the theme. Based on the analysis, the single domains such as CK, PK, TK were shown in the lesson plan. However, the complex domain of TPACK was rarely seen. The group discussions revealed that teacher educators need to become specific and explicit about which technology is being infused to support learning. It is significant to enhance the TPACK during planning in online microteaching classes and conduct further study of the implementation of this planning in the lesson. © 2021 Institute of physics Publishing. All rights reserved.

关键词： Planning

Partial observation can induce mechanistic mismatches in data-constrained models of neural dynamics 38

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Partial observation can induce mechanistic mismatches in dat...

38th Conference on Neural Information Processing Systems, NeurIPS 2024

作者： Qian, William Zavatone-Veth, Jacob A. Ruben, Benjamin S. Pehlevan, Cengiz Biophysics Graduate Program Harvard University CambridgeMA02138 United States Kempner Institute for the Study of Natural and Artificial Intelligence Harvard University CambridgeMA02138 United States John A. Paulson School of Engineering and Applied Sciences Harvard University CambridgeMA02138 United States Center for Brain Science Harvard University CambridgeMA02138 United States Department of Physics Harvard University CambridgeMA02138 United States

One of the central goals of neuroscience is to gain a mechanistic understanding of how the dynamics of neural circuits give rise to their observed function. A popular approach towards this end is to train recurrent neural networks (RNNs) to reproduce experimental recordings of neural activity. These trained RNNs are then treated as surrogate models of biological neural circuits, whose properties can be dissected via dynamical systems analysis. How reliable are the mechanistic insights derived from this procedure? While recent advances in population-level recording technologies have allowed simultaneous recording of up to tens of thousands of neurons, this represents only a tiny fraction of most cortical circuits. Here we show that observing only a subset of neurons in a circuit can create mechanistic mismatches between a simulated teacher network and a data-constrained student, even when the two networks have matching single-unit dynamics. In particular, partial observation of models of low-dimensional cortical dynamics based on functionally feedforward or low-rank connectivity can lead to surrogate models with spurious attractor structure. Our results illustrate the challenges inherent in accurately uncovering neural mechanisms from single-trial data, and suggest the need for new methods of validating data-constrained models for neural dynamics. © 2024 Neural information processing systems foundation. All rights reserved.

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Solving Combinatorial Optimization Problems on Fujitsu Digital Annealer

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arXiv 2023年

作者： Kao, Yu-Ting Liao, Jia-Le Hsu, Hsiu-Chuan Graduate Institute of Applied Physics National Chengchi University B.S. Program in Electrophysics National Chengchi University Department of Money and Banking National Chengchi University Taipei City Taiwan B.S. Program in Electrophysics National Chengchi University Department of Computer Science National Chengchi University Taipei City Taiwan Graduate Institute of Applied Physics National Chengchi University Department of Computer Science National Chengchi University Taipei City Taiwan

Combinatorial optimization problems are ubiquitous in various disciplines and applications. Many heuristic algorithms have been devoted to solve these types of problems. In order to increase the efficiency for finding the optimal solutions, an application–specific hardware, called digital annealer (DA) has been developed for solving combinatorial optimization problems using quadratic unconstrained binary optimization (QUBO) formulations. In this study, we formulated the number partitioning problem and the graph partitioning problem into QUBO forms and solved such problems with the DA developed by Fujitsu Ltd. The QUBO formulation of the number partitioning problem was fully connected. The DA found the overall runtime for the optimal solution to be less than 30 seconds for 6500 binary variables. For the graph partitioning problem, we adopted modularity as the metric for determining the quality of the partitions. For Zachary’s Karate Club graph, the modularity obtained was 0.445, a 6% increase against D–wave Quantum Annealer and Simulated Annealing. Moreover, to explore the DA’s potential applications to real–world problems, we used the search for communities or virtual microgrids in a power distribution network as an example. The problem was formulated into graph partitioning. It is shown that the DA effectively identified community structures in the IEEE 33–bus and IEEE 118–bus network. © 2023, CC BY.

关键词： Simulated annealing

Demonstration of a Polarization-Agnostic Geometric Phase in Nonlocal Metasurfaces

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arXiv 2023年

作者： Overvig, Adam Kasahara, Yoshiaki Xu, Gengyu Alù, Andrea Photonics Initiative Advanced Science Research Center Graduate Center of the City University of New York United States Department of Electrical and Computer Engineering The University of Texas Austin United States Physics Program Graduate Center City University of New York United States

Symmetry-driven phenomena arising in nonlocal metasurfaces supporting quasi-bound states in the continuum (q-BICs) have been opening new avenues to tailor enhanced light-matter interactions via perturbative design principles. Geometric phase concepts—observed in many physical systems—are particularly useful in nonlocal metasurfaces, as they enable to locally pattern the q-BIC scattering rate and phase across the metasurface aperture without affecting the delocalized nature of the q-BIC resonance. However, this control typically comes with stringent limitations in terms of efficiency and/or of polarization operation. Here, we unveil a new form of geometric phase control, accumulated along a continuous contour of geometric perturbations that parametrically encircle a singularity associated with a bound state. This response is obtained regardless of the chosen polarization state, which can be rationally specified by a judicious choice of the perturbation geometry. Our findings extend geometric phase concepts to arbitrary polarizations, including linear and elliptical states, with near-unity scattering efficiency. This polarization-agnostic geometric phase offers new opportunities for wavefront manipulation, multifunctional operation and light emission, with applications in augmented reality, secure communications, wireless systems, imaging, lasing, nonlinear and quantum optics. © 2023, CC BY.

关键词： Polarization