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arXiv 2024年

作者： Kumari, Priyanka Kurochkin, Olexandr Nazarenko, Vassili G. Lavrentovich, Oleg D. Golovaty, Dmitry Sternberg, Peter Advanced Materials and Liquid Crystal Institute Kent State University KentOH44242 United States Materials Science Graduate Program Kent State University KentOH44242 United States Institute of Physics National Academy of Sciences of Ukraine Prospect Nauky 46 Kyiv03028 Ukraine Institute of Physical Chemistry Polish Academy of Science Kasprzaka 44/52 Warsaw01-224 Poland Department of Physics Kent State University KentOH44242 United States Department of Mathematics The University of Akron AkronOH44325 United States Department of Mathematics Indiana University BloomingtonIN47405 United States

Domain structure of a fluid ferroelectric nematic is dramatically different from the domain structure of solid ferroelectrics since it is not restricted by rectilinear crystallographic axes and planar surface facets. We demonstrate that thin films of a ferroelectric nematic seeded by colloidal inclusions produce domain walls in the shape of conics such as a parabola. These conics reduce the bound charge within the domains and at the domain walls. An adequate description of the domain structures requires one to analyze the electrostatic energy, which is a challenging task. Instead, we demonstrate that a good approximation to the experimentally observed polydomain textures is obtained when the divergence of spontaneous polarization - which causes the bound charge is heavily penalized by assuming that the elastic constant of splay in the Oseen-Frank energy is much larger than those for twist and bend. The model takes advantage of the fact that the polarization vector is essentially parallel to the nematic director throughout the sample. © 2024, CC BY.

关键词： Polarization

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Single and double slit time diffraction at optical frequencies

Single and double slit time diffraction at optical frequenci...

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Frontiers in Optics, FiO 2022

作者： Tirole, Romain Vezzoli, Stefano Galiffi, Emanuele Tilmann, Benjamin Huidobro, Paloma A. Alù, Andrea Maier, Stefan A. Pendry, John B. Sapienza, Riccardo The Blackett Laboratory Department of Physics Imperial College London LondonSW7 2BW United Kingdom Photonics Initiative Advanced Science Research Center City University of New York 85 St. Nicholas Terrace New YorkNY10031 United States Hybrid Nanosystems Nanoinstitut München Ludwig-Maximilians-Universität München München80539 Germany Instituto de Telecomunicações Instituto Superior Tecnico University of Lisbon Avenida Rovisco Pais 1 Lisboa1049-001 Portugal Physics Program Graduate Center City University of New York New YorkNY10016 United States School of Physics and Astronomy Monash University ClaytonVIC3800 Australia

In a temporal version of a single slit and Young's double slit experiments, newly generated optical frequencies form a diffraction pattern. The spectral extent of these frequencies is beyond the expected bandwidth...

ISBN: (纸本)9781557528209

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Unifying (Machine) Vision via Counterfactual World Modeling

arXiv

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arXiv 2023年

作者： Bear, Daniel M. Feigelis, Kevin Chen, Honglin Lee, Wanhee Venkatesh, Rahul Kotar, Klemen Durango, Alex Yamins, Daniel L.K. Department of Psychology Stanford University StanfordCA94305 United States Department of Physics Stanford University StanfordCA94305 United States Department of Computer Science Stanford University StanfordCA94305 United States Department of Applied Physics Stanford University StanfordCA94305 United States Neurosciences Graduate Program Stanford University StanfordCA94305 United States Wu Tsai Neurosciences Institute Stanford University StanfordCA94305 United States

Leading approaches in machine vision employ different architectures for different tasks, trained on costly task-specific labeled datasets. This complexity has held back progress in areas, such as robotics, where robust task-general perception remains a bottleneck. In contrast, "foundation models" of natural language have shown how large pre-trained neural networks can provide zero-shot solutions to a broad spectrum of apparently distinct tasks. Here we introduce Counterfactual World Modeling (CWM), a framework for constructing a visual foundation model: a unified, unsupervised network that can be prompted to perform a wide variety of visual computations. CWM has two key components, which resolve the core issues that have hindered application of the foundation model concept to vision. The first is structured masking, a generalization of masked prediction methods that encourages a prediction model to capture the low-dimensional structure in visual data. The model thereby factors the key physical components of a scene and exposes an interface to them via small sets of visual tokens. This in turn enables CWM’s second main idea – counterfactual prompting – the observation that many apparently distinct visual representations can be computed, in a zero-shot manner, by comparing the prediction model’s output on real inputs versus slightly modified ("counterfactual") inputs. We show that CWM generates high-quality readouts on real-world images and videos for a diversity of tasks, including estimation of keypoints, optical flow, occlusions, object segments, and relative depth. Taken together, our results show that CWM is a promising path to unifying the manifold strands of machine vision in a conceptually simple foundation. © 2023, CC BY.

关键词： Computer vision

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Dispersion engineered metasurfaces for broadband, high-NA, high-efficiency, dual-polarization analog image processing

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Nature Communications 2023年第1期14卷 7078页

作者： Cotrufo, Michele Arora, Akshaj Singh, Sahitya Alù, Andrea Photonics Initiative Advanced Science Research Center City University of New York New York 10031 NY United States The Institute of Optics University of Rochester Rochester 14627 NY United States Physics Program Graduate Center of the City University of New York New York 10016 NY United States

Optical metasurfaces performing analog image processing – such as spatial differentiation and edge detection – hold the potential to reduce processing times and power consumption, while avoiding bulky 4 F lens systems. However, current designs have been suffering from trade-offs between spatial resolution, throughput, polarization asymmetry, operational bandwidth, and isotropy. Here, we show that dispersion engineering provides an elegant way to design metasurfaces where all these critical metrics are simultaneously optimized. We experimentally demonstrate silicon metasurfaces performing isotropic and dual-polarization edge detection, with numerical apertures above 0.35 and spectral bandwidths of 35 nm around 1500 nm. Moreover, we introduce quantitative metrics to assess the efficiency of these devices. Thanks to the low loss nature and dual-polarization response, our metasurfaces feature large throughput efficiencies, approaching the theoretical maximum for a given NA. Our results pave the way for low-loss, high-efficiency and broadband optical computing and image processing with free-space metasurfaces. © 2023, The Author(s).

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Diffusive and Fluidlike Motion of Homochiral Domain Walls in Easy-Plane Magnetic Strips

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Physical Review Applied 2021年第5期16卷 054002-054002页

作者： David A. Smith So Takei Bella Brann Lia Compton Fernando Ramos-Diaz Matthew J. Simmers Satoru Emori Department of Physics Virginia Tech Blacksburg Virginia 24061 USA Department of Physics Queens College City University of New York Queens New York 11367 USA Physics Doctoral Program The Graduate Center City University of New York New York New York 10016 USA Academy of Integrated Science Virginia Tech Blacksburg Virginia 24061 USA

Propagation of easy-plane magnetic precession can enable more efficient spin transport than conventional spin waves. Such easy-plane spin transport is typically understood in terms of a hydrodynamic model, partially analogous to superfluids. Here, using micromagnetic simulations, we examine easy-plane spin transport in magnetic strips as the motion of a train of domain walls rather than as a hydrodynamic flow. We observe that the motion transitions from diffusive to fluidlike as the density of domain walls is increased. This transition is most evident in notched nanostrips, where the domain walls are pinned by the notch defect in the diffusive regime but propagate essentially unimpeded in the fluidlike regime. Our findings suggest that spin transport via easy-plane precession, robust against defects, is achievable in strips based on realistic metallic ferromagnets and hence amenable to practical device applications.

关键词： Defects Domain walls Magnetic domains Magnetization dynamics Spin waves Transport phenomena Nanostructures Micromagnetic modeling

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Million-Q Free Space Meta-Optical Resonator at Visible Wavelengths

arXiv

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arXiv 2024年

作者： Fang, Jie Chen, Rui Sharp, David Renzi, Enrico M. Manna, Arnab Kala, Abhinav Mann, Sander A. Yao, Kan Munley, Christopher Rarick, Hannah Tang, Andrew Pumulo, Sinabu Zheng, Yuebing Menon, Vinod M. Alù, Andrea Majumdar, Arka Department of Electrical and Computer Engineering University of Washington SeattleWA98195 United States Department of Physics University of Washington SeattleWA98195 United States Photonics Initiative Advanced Science Research Center City University of New York New YorkNY10031 United States Physics Program Graduate Center City University of New York New YorkNY10016 United States Walker Department of Mechanical Engineering Texas Materials Institute The University of Texas at Austin AustinTX78712 United States Department of Materials Science and Engineering University of Washington SeattleWA98195 United States Department of Physics City College of New York New YorkNY10031 United States

High-quality (Q)-factor optical resonators with extreme temporal coherence are of both technological and fundamental importance in optical metrology1,2, continuous-wave lasing3-5, and semiconductor quantum optics6-8. Despite extensive efforts in designing high-Q resonators across different spectral regimes, the experimental realization of very large Q-factors at visible wavelengths remains challenging due to the small feature size that is sensitive to fabrication imperfections9-12, and thus is typically implemented in integrated photonics1-4,9,10. In the pursuit of free-space optics with the benefits of large space-bandwidth product and massive parallel operations13,14, here we design and fabricate a visible-wavelength etch-free metasurface with minimized fabrication defects and experimentally demonstrate a million-scale ultrahigh-Q resonance. A new laser-scanning momentum-space-resolved spectroscopy technique with extremely high spectral and angular resolution is developed to characterize the record-high Qfactor as well as the dispersion of the million-Q resonance in free space. By integrating monolayer WSe2 into our ultrahigh-Q meta-resonator, we further demonstrate laser-like highly unidirectional and narrow-linewidth exciton emission, albeit without any operating power density threshold. Under continuous-wave laser pumping, we observe pump-power-dependent linewidth narrowing at room temperature, indicating the potential of our meta-optics platform in controlling coherent quantum light-sources. Our result also holds great promise for applications like optical sensing, spectral filtering, and few-photon nonlinear optics. Copyright © 2024, The Authors. All rights reserved.

关键词： Continuous wave lasers

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Computational design of serine hydrolases

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science (New York, N.Y.) 2025年第6744期388卷 eadu2454页

作者： Lauko, Anna Pellock, Samuel J. Sumida, Kiera H. Anishchenko, Ivan Juergens, David Ahern, Woody Jeung, Jihun Shida, Alexander F. Hunt, Andrew Kalvet, Indrek Norn, Christoffer Humphreys, Ian R. Jamieson, Cooper Krishna, Rohith Kipnis, Yakov Kang, Alex Brackenbrough, Evans Bera, Asim K. Sankaran, Banumathi Houk, K.N. Baker, David Department of Biochemistry University of Washington Seattle WA United States Institute for Protein Design University of Washington Seattle WA United States Graduate Program in Biological Physics Structure and Design University of Washington Seattle WA United States Department of Chemistry University of Washington Seattle WA United States Graduate Program in Molecular Engineering University of Washington Seattle WA United States Paul G. Allen School of Computer Science and Engineering University of Washington Seattle WA United States Medical Scientist Training Program University of Washington Seattle WA United States Howard Hughes Medical Institute University of Washington Seattle WA United States Department of Chemistry and Biochemistry University of California Los Angeles CA United States

The design of enzymes with complex active sites that mediate multistep reactions remains an outstanding challenge. With serine hydrolases as a model system, we combined the generative capabilities of RFdiffusion with an ensemble generation method for assessing active site preorganization at each step in the reaction to design enzymes starting from minimal active site descriptions. Experimental characterization revealed catalytic efficiencies (kcat/Km) up to 2.2 × 105 M-1 s-1 and crystal structures that closely match the design models (Cα root mean square deviations <1 angstrom). Selection for structural compatibility across the reaction coordinate enabled identification of new catalysts remove with five different folds distinct from those of natural serine hydrolases. Our de novo approach provides insight into the geometric basis of catalysis and a roadmap for designing enzymes that catalyze multistep transformations.

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Systematic designs of single metal compounds synthesized using ammonia fluoride-based complex as structure directing agents for energy storage

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Journal of Colloid and Interface science 2023年第PartA期652卷 294-304页

作者： Kuo, Tsung-Rong Zher Yu, You Wu, Chung-Hsien Lee, Pin-Yan Kongvarhodom, Chutima Chen, Hung-Ming Husain, Sadang Yougbaré, Sibidou Lin, Lu-Yin International PhD Program in Biomedical Engineering College of Biomedical Engineering Taipei Medical University Taipei11031 Taiwan Graduate Institute of Nanomedicine and Medical Engineering College of Biomedical Engineering Taipei Medical University Taipei11031 Taiwan Department of Chemical Engineering and Biotechnology National Taipei University of Technology Taipei Taiwan Department of Chemical Engineering King Mongkut's University of Technology Thonburi 126 Pracha-u-thit Toong-kru Bangkok10140 Thailand Gingen technology Co. LTD. Rm. 7 10F. No.189 Sec. 2 Keelung Rd. Xinyi Dist. Taipei11054 Taiwan Department of Physics Faculty of Mathematics and Natural Science Lambung Mangkurat University Banjarmasin70124 Indonesia /Nanoro 03 B.P 7192 Ouagadougou 03 Burkina Faso

Tailoring morphology and composition of metal organic frameworks (MOF) can improve energy storage by establishing high surface area, large porosity and multiple redox states. Structure directing agents (SDA) is functional of designing surface properties of electroactive materials. Ammonium fluoride has functional abilities for designing MOF derivatives with excellent energy storage abilities. Systematic design of MOF derivatives using ammonia fluoride-based complex as SDA can essentially create efficient electroactive materials. Metal species can also play significant roles on redox reactions, which are the main energy storage mechanism for battery-type electrodes. In this work, 2-methylimidazole, two novel SDAs of NH4BF4 and NH4HF2, and six metal species of Al, Mn, Co, Ni, Cu and Zn are coupled to synthesize MOF derivatives for energy storage. Metal species-dependent compositions including hydroxides, oxides, and hydroxide nitrates are observed. The nickel-based derivative (Ni-HBF) shows the highest specific capacitance (CF) of 698.0F/g at 20 mV/s, due to multiple redox states and advanced flower-like surface properties. The diffusion and capacitive-control contributions of MOF derivatives are also analyzed. The battery supercapacitor hybrid with Ni-HBF electrode shows a maximum energy density of 27.9 Wh/kg at 325 W/kg. The CF retention of 170.9% and Coulombic efficiency of 93.2% are achieved after 10,000 cycles. © 2023 Elsevier Inc.

关键词： Supercapacitor

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Iterative quantum optimization of spin glass problems with rapidly oscillating transverse fields

arXiv

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arXiv 2024年

作者： Barton, Brandon Sagal, Jacob Feeney, Sean Grattan, George Patnaik, Pratik Oganesyan, Vadim Carr, Lincoln D. Kapit, Eliot Quantum Engineering Program Colorado School of Mines 1523 Illinois St GoldenCO80401 United States Department of Applied Mathematics and Statistics Colorado School of Mines 1500 Illinois St GoldenCO80401 United States Center for Computational Quantum Physics Flatiron Institute 162 5th Avenue New YorkNY10010 United States Department of Physics Colorado School of Mines 1523 Illinois St GoldenCO80401 United States Department of Computer Science Colorado School of Mines 1500 Illinois St GoldenCO80401 United States Department of Physics and Astronomy College of Staten Island City University of New York Staten IslandNY10314 United States Physics program and Initiative for the Theoretical Sciences The Graduate Center City University of New York New YorkNY10016 United States

In this work, we introduce a new iterative quantum algorithm, called Iterative Symphonic Tunneling for Satisfiability problems (IST-SAT), which solves quantum spin glass optimization problems using high-frequency oscillating transverse fields. IST-SAT operates as a sequence of iterations, in which bitstrings returned from one iteration are used to set spin-dependent phases in oscillating transverse fields in the next iteration. Over several iterations, the novel mechanism of the algorithm steers the system toward the problem ground state. We benchmark IST-SAT on sets of hard MAX-3-XORSAT problem instances with exact state vector simulation, and report polynomial speedups over trotterized adiabatic quantum computation (TAQC) and the best known semi-greedy classical algorithm. When IST-SAT is seeded with a sufficiently good initial approximation, the algorithm converges to exact solution(s) in a polynomial number of iterations. Our numerical results identify a critial Hamming radius(CHR), or quality of initial approximation, where the time-to-solution crosses from exponential to polynomial scaling in problem size. By combining IST-SAT with future classical or quantum approximation algorithms, larger gains may be achieved. The mechanism we present in this work thus presents a new path toward achieving quantum advantage in optimization. © 2024, CC BY.

关键词： Combinatorial optimization

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Doping Engineered InSe Flakes for High Mobility Phototransistor

Doping Engineered InSe Flakes for High Mobility Phototransis...

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Novel Optical Materials and Applications, NOMA 2020

作者： Inbaraj, Christy Roshini Paul Mathew, Roshan Jesus Sankar, Raman Lee, Chih-Hao Chen, Yang-Fang Department of Engineering and System Science National Tsing Hua University Hsinchu Taiwan Nano-Science and Technology Program Taiwan International Graduate Program Academia Sinica Taipei Taiwan Center for Condensed Matter Sciences National Taiwan University Taipei Taiwan Department of Physics National Taiwan University Taipei Taiwan

Sn doped InSe crystal has a reduced oxide phase and enhanced electron mobility. Along with the substrate modification, the mobility enhances to 2560 240 cm2 V-1s-1. Moreover, it exhibits a piezo-phototronic effect use... 详细信息

ISBN: (纸本)9781943580798

关键词： Indium compounds

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