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Closed and open superconducting microwave waveguide networks as a model for quantum graphs

Physical Review E 2024年第3期109卷 034201-034201页

作者： Barbara Dietz Tobias Klaus Marco Masi Maksym Miski-Oglu Achim Richter Tatjana Skipa Marcus Wunderle Center for Theoretical Physics of Complex Systems Institute for Basic Science (IBS) Daejeon 34126 Korea Basic Science Program Korea University of Science and Technology (UST) Daejeon 34113 Republic of Korea Institut für Kernphysik Technische Universität Darmstadt D-64289 Darmstadt Germany GSI Helmholtzzentrum für Schwerionenforschung GmbH D-64291 Darmstadt Germany Darmstadt University of Applied Sciences D-64295 Darmstadt Germany

We report on high-precision measurements that were performed with superconducting waveguide networks with the geometry of a tetrahedral and a honeycomb graph. They consist of junctions of valency three that connect straight rectangular waveguides of equal width but incommensurable lengths. The experiments were performed in the frequency range of a single transversal mode, where the associated Helmholtz equation is effectively one-dimensional and waveguide networks may serve as models of quantum graphs with the joints and waveguides corresponding to the vertices and bonds. The tetrahedral network comprises T junctions, while the honeycomb network exclusively consists of Y junctions, that join waveguides with relative angles 90∘ and 120∘, respectively. We demonstrate that the vertex scattering matrix, which describes the propagation of the modes through the junctions, strongly depends on frequency and is nonsymmetric at a T junction and thus differs from that of a quantum graph with Neumann boundary conditions at the vertices. On the other hand, at a Y junction, similarity can be achieved in a certain frequency range. We investigate the spectral properties of closed waveguide networks and fluctuation properties of the scattering matrix of open ones and find good agreement with random matrix theory predictions for the honeycomb waveguide graph.

关键词： Quantum chaos Wave chaos

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Effective Dimension Aware Fractional-Order Stochastic Gradient Descent for Convex Optimization Problems

arXiv

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arXiv 2025年

作者： Partohaghighi, Mohammad Marcia, Roummel Chen, YangQuan Electrical Engineering and Computer Science graduate program University of California Merced United States Department of Applied Mathematics University of California Merced MercedCA United States Lab Department of Mechanical Engineering School of Engineering University of California MercedCA95343 United States

Fractional-order stochastic gradient descent (FOSGD) leverages a fractional exponent to capture long-memory effects in optimization, yet its practical impact is often constrained by the difficulty of tuning and stabilizing this exponent. In this work, we introduce 2SED Fractional-Order Stochastic Gradient Descent (2SEDFOSGD), a novel method that synergistically combines the Two-Scale Effective Dimension (2SED) algorithm with FOSGD to automatically calibrate the fractional exponent in a data-driven manner. By continuously gauging model sensitivity and effective dimensionality, 2SED dynamically adjusts the exponent to curb erratic oscillations and enhance convergence rates. Theoretically, we demonstrate how this dimension-aware adaptation retains the benefits of fractional memory while averting the sluggish or unstable behaviors frequently observed in naive fractional SGD. Empirical evaluations across multiple benchmarks confirm that our 2SED-driven fractional exponent approach not only converges faster but also achieves more robust final performance, suggesting broad applicability for fractional-order methodologies in large-scale machine learning and related domains. © 2025, CC BY.

关键词： Convex optimization

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Long-range photodetection of organic exciton-polaritons

Long-range photodetection of organic exciton-polaritons

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Conference on Lasers and Electro-Optics (CLEO)

作者： Bin Liu Xinjing Huang Stephen R. Forrest Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor USA Applied Physics Program University of Michigan Ann Arbor USA Department of Physics University of Michigan Ann Arbor USA Department of Material Science and Engineering University of Michigan Ann Arbor USA

In light-matter strong coupling regime, we observe long-range photodetection response at room temperature mediated by organic exciton-polaritons, which results from strong interactions between organic excitons and low... 详细信息

ISBN: (数字)9781957171050

ISBN: (纸本)9781665466660

关键词： Couplings Surface waves Excitons Lasers and electrooptics Laser excitation Electrooptical waveguides

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Multi-Instance Task in Swarm Robotics: Sorting Groups of Robots or Objects into Clusters with Minimalist Controllers

Multi-Instance Task in Swarm Robotics: Sorting Groups of Rob...

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IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)

作者： Adilson Krischanski Yuri K. Lopes Andre B. Leal Ricardo F. Martins Roberto S.U. Rosso Department of Computer Science Santa Catarina State University (UDESC) Joinville Brazil Graduate Program in Applied Computing (PPGCAP) UDESC Brazil Department of Electrical Engineering Santa Catarina State University (UDESC) Joinville Brazil

Relying only on behaviors that emerge from simple responsive controllers; swarms of robots have been shown capable of autonomously aggregate themselves or objects into clusters without any form of communication. We push these controllers to the limit, requiring robots to sort themselves or objects into different clusters. Based on a responsive controller that maps the current reading of a line-of-sight sensor to a pair of speeds for the robots' differential wheels, we demonstrate how multiple tasks instances can be accomplished by a robotic swarm. Using the dividing rectangles approach and physics simulation, a training step optimizes the parameters of the controller guided by a fitness function. We conducted a series of systematic trials in physics-based simulation and evaluate the performance in terms of dispersion and the ratio of clustered robots/objects. Across 20 trials where 30 robots cluster themselves into 3 groups, an average of 99.83% of them were correctly clustered into their group after 300 s. Across 50 trials where 15 robots cluster 30 objects into 3 groups, an average of 61.20%, 82.87%, and 97.73% of objects were correctly clustered into their group after 600 s, 900 s, and 1800 s, respectively. The object cluster behavior scales well while the aggregation does not, the latter due to the requirement of control tuning based on the number of robots.

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Venipuncture training assists using electrical sensors in a rubber arm system 15

Venipuncture training assists using electrical sensors in a ...

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15th Siam physics Congress, SPC 2020

作者： Saengpayab, Y. Kongsri, W. Chongsereecharoen, E. Pratummasoot, N. Akkarapattanapong, V. Jarintanan, F. Applied Physics Program Faculty of Science and Technology Valaya Alongkorn Rajabhat University under the Royal Patronage Pathum Thani13180 Thailand Industrial Metrology and Quality System Program Faculty of Science and Technology Valaya Alongkorn Rajabhat University under the Royal Patronage Pathum Thani13180 Thailand Faculty of Medical Science Technology Rangsit University Pathumthani12000 Thailand

The main purpose of the present study was to implement a sensor system to help improving the venipuncture accuracy for medical technology students using a rubber arm system. The rubber arm simulated human arm having veins with a pump circulated fluid inside. The fluid represented human blood which is usually withdrawn at three areas of vein in the arms, i.e., median cephalic, median basilic, and median cubital veins. The venipuncture sensing system consists of the electrical sensors connected to the rubber arm, a needle and a control box. The arm sensor was designed to detect electric quantities derived as the result of different resistances of needle tip in different materials. Three testers performed ten venipuncture tests at each at the three locations by using the sensor system. During the test, the numbers of venipuncture and various types of venipuncture output were collected by the sensor. Based on the results, the accuracy of the venipuncture was determined. It was found that the average accuracy was 76±10%. Moreover, the training effectiveness of the system was evaluated by divided the accuracy results into two parts i.e., the first half and the second half of the tests. Accuracy comparisons was made between these parts. It was found that the accuracy was improved at all three areas along with the reduced through venipuncture percentage. This research provided an optional possibility of using a venipuncture sensor for medical technology students. © Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence.

关键词： Rubber

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Investigating the computation of smoothed deceptive routes in topographic terrains for agent-based simulation systems

Investigating the computation of smoothed deceptive routes i...

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Computational Intelligence in Security, Defence and Biometrics (CISDB), IEEE Symposium on

作者： Luigi P. Souza Thiago R. S. Leão Crhistopher Lenhard Edison P. Freitas Luis A. L. Silva Graduate Program in Computer Science Federal Univ. of Santa Maria Santa Maria Brazil Undergraduate Course in Computer Science Federal Univ. of Santa Maria Santa Maria Brazil Institute of Informatics Federal Univ. of Rio Grande do Sul Porto Alegre Brazil Applied Computing Department Federal Univ. of Santa Maria Santa Maria Brazil

ISBN: (数字)9798331508296

ISBN: (纸本)9798331508302

The capacity to deceptively move in hilly terrains is fundamental to agents in simulation systems for tactical and strategic military training. Such an ability to deceive the adversary can ensure a relevant advantage by hiding the real goals of a mission. Using pairs of real and deceptive mission goals, this paper investigates the planning of realistic deceptive routes for simulated agents. With real-world terrain elevation maps, it shows how to explore pathfinding algorithms with relevant path-smoothing characteristics (Theta* and WJPS*, contrasting with the standard $A^{*}$ algorithm) in terrains with pronounced relief features. The study analyzes the effects of terrain elevation costs and the representation of relief contour lines on the determination of more realistic deceptive paths. This work also investigates how users can adjust a Last Topographic Deceptive Point ($L D P_{T}$) calculation to enhance the pathfinding algorithm’s ability to produce more deceptively dense and topographically aware routes. Experimental results for different deceptive topographic path planning strategies are evaluated according to statistical models showing that Theta*, despite being slower than the base $A^{*}$ method in most cases, generated smoothed paths while maintaining a similar deception density for the proposed strategies. On the other hand, WJPS outperformed both in execution time for certain strategies while maintaining the smoothed path characteristic and resulting in a path with lower deceptive capacity.

关键词： Training Hands Biometrics Costs Path planning Planning Security Standards Computational intelligence

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Selective-Area Growth of Gan and Algan Nanowires on N-Polar Gan Templates with 4° Miscut by Plasma-Assisted Molecular Beam Epitaxy

SSRN

引用

SSRN 2022年

作者： Khan, Kamruzzaman Jian, Zhe Li, Jonathan Sun, Kai Ahmadi, Elaheh Department of Materials Science and Engineering University of Michigan Ann Arbor United States Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor United States Applied Physics Program University of Michigan Ann Arbor United States

In this study, selective area growth (SAG)s of AlGaN/GaN nanowires (NWs) on miscut N-polar GaN templates were studied and compared with that grown on Ga-polar templates using plasma-assisted molecular beam epitaxy (MBE). The SAG of N-polar AlGaN/GaN NWs demonstrated higher growth rate and more growth selectivity than that of Ga-polar AlGaN/GaN NWs. Additionally, lateral growth rate of N-polar NWs was significantly lower than Ga-polar NWs. Compared to the pyramidal shaped top surfaces of Ga-polar NWs, the N-polar GaN NWs had flat head top surfaces. The combination of higher growth selectivity, larger growth window, negligible lateral growth, and flat head, makes N-polar (Al,Ga)N NWs attractive for a variety of applications including UV LEDs and detectors as well as quantum sensing. © 2022, The Authors. All rights reserved.

关键词： Aluminum gallium nitride

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Design and deployment of radiological point-source arrays for the emulation of continuous distributed sources

arXiv

引用

arXiv 2022年

作者： Vavrek, Jayson R. Hines, C. Corey Bandstra, Mark S. Hellfeld, Daniel Heine, Maddison A. Heiden, Zachariah M. Mann, Nick R. Quiter, Brian J. Joshi, Tenzing H.Y. The Applied Nuclear Physics program Lawrence Berkeley National Laboratory United States The Nuclear Science Center Washington State University United States The National and Homeland Security Research Program Idaho National Laboratory United States

We demonstrate a method for using arrays of point sources that emulate—when measured from a standoff of at least several meters—distributed gamma-ray sources, and present results using this method from outdoor aerial measurements of several planar arrays each comprising up to 100 ∼7 mCi Cu-64 sealed sources. The method relies on the Poisson deviance to statistically test whether the array source "looks like" its continuous analogue to a particular gamma-ray detector given the counts recorded as the detector moves about 3D space. We use this deviance metric to design eight different mock distributed sources, ranging in complexity from a 36×36 m uniform square grid of sources to a configuration where regions of higher and zero activity are superimposed on a uniform baseline. We then detail the design, manufacture, and testing of the ∼7 mCi Cu-64 sealed sources at the Washington State University research reactor, and their deployment during the aerial measurement campaign. We show the results of two such measurements, in which approximate source shapes and qualitative source intensities can be seen. Operationally, we find that the point-source array technique provides high source placement accuracy and ease of quantifying the true source configuration, scalability to source dimensions of 100 m, ease of reconfiguration and removal, and relatively low dose to personnel. Finally, we consider potential improvements and generalizations of the point-source array technique for future measurement campaigns. Copyright © 2022, The Authors. All rights reserved.

关键词： Antennas

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Higher-Order Photonic Topological States in Split-Ring Resonators-Based Kagome Lattice

Higher-Order Photonic Topological States in Split-Ring Reson...

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CLEO: QELS_Fundamental science, QELS 2022

作者： Zhirihin, D. Bobylev, D. Tihonenko, D. Vakulenko, A. Smirnova, D. Khanikaev, A. Gorlach, M. School of Physics and Engineering ITMO University 49 Kronverksky ave. Saint Petersburg197101 Russia Grove School of Engineering City College of the City University of New York New YorkNY United States Physics Program Graduate Center of the City University of New York New YorkNY United States Nonlinear Physics Centre Australian National University CanberraACT Australia Institute of Applied Physics Russian Academy of Science Nizhny Novgorod Russia

We demonstrate experimentally the emergence of higher-order topological states induced by bianisotropy in a photonic metasurface formed by split-ring resonators (SRR) arranged into a kagome lattice. © Optica Publ... 详细信息

ISBN: (纸本)9781557528209

关键词： Topology

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Real-space and reciprocal-space topology in the Eu(Ga1−xAlx)4 square net system

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Physical Review B 2023年第6期108卷 064436-064436页

作者： Jaime M. Moya Jianwei Huang Shiming Lei Kevin Allen Yuxiang Gao Yan Sun Ming Yi E. Morosan Applied Physics Graduate Program Rice University Houston Texas 77005 USA Department of Physics and Astronomy Rice University Houston Texas 77005 USA Rice Center for Quantum Materials (RCQM) Rice University Houston Texas 77005 USA Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang Liaoning 110016 China

Magnetotransport measurements of the centrosymmetric square net Eu(Ga1−xAlx)4 compounds reveal evidence of both reciprocal- and real-space topology. For compositions 0.50≤x≤0.90, several intermediate field phases are found by magnetization measurements when H∥c, where a maximum in the topological Hall effect is observed, pointing to the existence of topological (real-space topology) or noncoplanar spin textures. For 0.25≤x≤0.39, magnetization measurements reveal an intermediate field state, but no transition is visible in the Hall measurements. For x=0.15, only one magnetic transition occurs below the Néel temperature TN, and no intermediate field spin reorientations are observed. The Hall effect varies smoothly before the spin-polarized (SP) state. However, in the SP state, Hall measurements reveal a large anomalous Hall effect (AHE) for all compositions, a consequence of reciprocal-space topology. Density functional theory calculations in the paramagnetic state indeed reveal a Dirac point that lies very near the Fermi energy, which is expected to split into Weyl nodes in the SP state, thereby explaining the observed AHE. These results suggest the Eu(Ga1−xAlx)4 family is a rare material platform where real- and reciprocal-space topology exist in a single material platform.

关键词： Electrical conductivity Electronic structure Hall effect Magnetic order Magnetic texture Magnetotransport Topological order Topological phases of matter Density functional calculations Magnetization measurements Resistivity measurements

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