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2006 MRS Fall Meeting

作者： Hazair, S. Van Der Wilt, P.C. Deng, Y. Chung, U.-J. Limanov, A.B. Im, James S. Program of Materials Science Department of Applied Physics and Applied Mathematics Columbia University New York NY 10027 United States

ISBN: (纸本)9781604234282

Thin Si films on SiO2 that are completely melted by pulsed laser irradiation cool rapidly and eventually solidify via nucleation and growth of solids. It has been observed that a variety of solidified microstructures can be obtained, depending primarily (but not exclusively) on the degree of supercooling achieved prior to the onset of nucleation. This paper focuses on investigating one particular and unusual polycrystalline microstructure that consists of "flower-like" grains, the interiors of which can be described as being made up of two distinct regions: (1) an extremely defective core region consisting of fine-grained material, and (2) an outer region consisting of relatively defect-free crystal "petals" that radiate outwards. After considering the microstructural details and experimental behavior of the microstructure, we have formulated a growth-based physical model to account for the formation of the microstructure. The model is found to be also capable of accounting for other complex and unusual microstructures obtained via nucleation and growth in the complete melting regime. © 2007 Materials Research Society.

关键词： Thin films

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Wave-driver options for low aspect ratio steady-state tokamak reactors

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Journal of Fusion Energy 1981年第4期1卷 357-365页

作者： Ehst, David A. Fusion Power Program Applied Physics Division Argonne National Laboratory Argonne 60439 Illinois United States

Low aspect ratio designs are proposed for steady-state tokamak reactors. Benefits stem from reduced major radius and lessened stresses in the toroidal field coils, resulting in possible cost savings in the tokamak construction. In addition, a low aspect ratio (A=2.6) permits the application of a bundle divertor capable of diverting 3-T fields to a power reactor using STARFIRE technology. Such a low aspect ratio is possible with the elimination of poloidal field coils in the central hole of the tokamak, which implies a need for noninductive current drive. Several plasma waves are considered for this application, and it appears likely that a candidate can be found which reduces the electric power for current maintenance to an acceptable value. © 1981 Plenum Publishing Corporation.

关键词： bundle divertor low-aspect ratio steady-state tokamak tokamak reactor wave-driven currents

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Numerical Analysis of QCW-Laser-Based Spot-Beam Crystallization of Si Films

Numerical Analysis of QCW-Laser-Based Spot-Beam Crystallizat...

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SID Symposium, Seminar, and Exhibition 2017, Display Week 2017

作者： Pann, Wenkai Song, Ruobing Suresh, Akhilesh K. Wong, Vernon K. Yu, Miao Choi, Insung Im, James S. Program in Materials Science and Engineering Department of Applied Physics and Applied Mathematics Columbia University New YorkNY United States

ISBN: (纸本)9781510848757

We are in the process of developing a new laser annealing method referred to as Spot-Beam Crystallization (SBC). The SBC method, which is potentially well suited for manufacturing advanced ultra-high-resolution AMOLED displays, is most effectively implemented using ultra-high- frequency quasi-continuous-wave (QCW) pulsed lasers. Conceptually and physically, this QCW-laser-based SBC (Q- SBC) approach builds on a thermally additive utilization of multiple short-lived ultra-high-frequency pulses, achieved via overlapped scanning of a small spot beam to incrementally and gradually heat and melt the beam-irradiated region. Using an updated version of a previously developed numerical program, we have carried out a simulation-based investigation to quantitatively examine and evaluate the basic tenets of the approach relevant specifically to partial-melting-based "ELA- like" crystallization of small-columnar-grained polycrystalline Si films using the Q-SBC method. The results from the effort to date as reported in this paper (1) largely confirm and validate the viability of the Q-SBC approach, and (2) suggest some specific directions for optimal development of the Q-SBC equipment and process. © 2017 SID.

关键词： Continuous wave lasers

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Conversion of twisted light to twisted excitons using carbon nanotubes

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npj Computational Materials 2022年第1期8卷 392-402页

作者： Xiaoning Zang Nirpendra Singh Mark T.Lusk Udo Schwingenschlögl Applied Physics Program Physical Sciences and Engineering DivisionKing Abdullah University of Science and Technology(KAUST)Thuwal23955-6900Saudi Arabia Department of Physics Khalifa University of Science and TechnologyAbu Dhabi127788United Arab Emirates Department of Physics Colorado School of MinesGoldenCO80401USA

Carbon nanotubes are explored as a means of coherently converting the orbital angular momentum of light to an excitonic form that is more amenable to quantum information *** analytical analysis,based on dynamical conductivity,is used to show that orbital angular momentum is conserved,modulo N,for a carbon nanotube illuminated by radially polarized,twisted *** result is numerically demonstrated using real-time time-dependent density functional theory which captures the absorption of twisted light and the subsequent transfer of twisted *** results suggest that carbon nanotubes are promising candidates for constructing optoelectronic circuits in which quantum information is more readily processed while manifested in excitonic form.

关键词： twisted carbon light

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Epitaxial growth following crystal nucleation in laser-quenched Si filins on SiO2

Epitaxial growth following crystal nucleation in laser-quenc...

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2015 MRS Spring Meeting

作者： Wong, Vemon K. Chitu, A.M. Limanov, A.B. Im, James S. Program in Materials Science and Engineering Department of Applied Physics and Applied Mathematics Columbia University New YorkNY United States

ISBN: (纸本)9781510826267

We have investigated the solidified microstructure of nucleation-generated grains obtained via complete melting of Si films on SiO2 at high nucleation temperatures. This was achieved using a high-temperature-capable hot stage in conjunction with excimer laser irradiation. As predicted by the direct-growth model that considers (1) the evolution in the temperature of the solidifying interface and (2) the subsequent modes of growth (consisting of amorphous, defective, and epitaxial) as key factors, we were able to observe the appearance of "normal" grains that possess a single-crystal core area. These grains, which are in contrast to previously reported flower-shaped grains that fully make up the microstructure of the solidified films obtained via irradiation at lower preheating temperatures (and amongst which these "normal" grains emerge), indicate that epitaxial growth of nucleated crystals must have taken place within the grains. We discuss the implications of our findings regarding (1) the validity of the direct-growth model, (2) the nature of the heterogeneous nucleation mechanism, and (3) the alternative explanations and assumptions that have been previously employed in order to explain the microstructure of Si films obtained via nucleation and growth within the complete melting regime. © 2015 Materials Research Society.

关键词： Silica

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From Dyson models to many-body quantum chaos

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Physical Review B 2025年第3期111卷 035147-035147页

作者： Alexei Andreanov Matteo Carrega Jeff Murugan Jan Olle Dario Rosa Ruth Shir 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 Korea CNR-SPIN Via Dodecaneso 33 16146 Genova Italy The Laboratory for Quantum Gravity & Strings Department of Mathematics and Applied Mathematics University of Cape Town Cape Town 7701 South Africa The National Institute for Theoretical and Computational Sciences Private Bag X1 Matieland 7602 South Africa Max Planck Institute for the Science of Light 91058 Erlangen Germany ICTP South American Institute for Fundamental Research Instituto de Física Teórica UNESP—University of Estadual Paulista Rua Dr. Bento Teobaldo Ferraz 271 01140-070 São Paulo SP Brazil Department of Physics and Materials Science University of Luxembourg L-1511 Luxembourg Luxembourg

A deep understanding of the mechanisms underlying many-body quantum chaos is one of the big challenges in contemporary theoretical physics. We tackle this problem in the context of a set of perturbed quadratic Sachdev-Ye-Kitaev (SYK) Hamiltonians defined on graphs. This allows us to disentangle the geometrical properties of the underlying single-particle problem and the importance of the interaction terms, showing that the former is the dominant feature ensuring the single-particle to many-body chaotic transition. Our results are verified numerically with state-of-the-art numerical techniques, capable of extracting eigenvalues in a desired energy window of very large Hamiltonians. Our approach essentially provides a new way of viewing many-body chaos from a single-particle perspective.

关键词： Quantum chaos

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ON WORST CASE INTERFERENCE FOR M-ARY SIGNALING WITH CORRELATION RECEIVERS

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IEEE TRANSACTIONS ON INFORMATION THEORY 1982年第1期28卷 74-83页

作者： MORRIS, JM Applied Physics Laboratory Johns Hopkins University Laurel MD USA Electronic and Solid-State Sciences Program Office of Naval Research Arlington VA USA

Specification of the worst case additive interference for M -ary signaling and receivers using predecision correlation is obtained. The interference is constrained by average power and peak amplitude upper bounds on its Fourier transform. In addition, no statistical description is assumed. The performance measure is a weighted (\pm 1) sum of the correlations between the received corrupted signal Fourier transform R_{m}(f) and each member of the signal set Fourier transforms \{S_{m}(f)\} . This measure also depends on the out-of-sync time shift t and the signal present probability p . Functional analysis concepts are utilized to state and solve the resulting generalized Lagrange multiplier problem in L_{2} . The worst case interference function W^{0}(f) is shown to have an average power equal to the average power upper bound and is independent of p , but dependent on t . A key parameter may need numerical techniques for evaluation. This power level is achieved with W^{0} as a clipped multiple of | \sum S_{m}| that follows the phase of \sum S_{m}(f) . The clipping level is the peak amplitude upper bound. The worst case performance is explicitly expressed in terms of W^{0} . Upper and lower bounds are also derived with respect to arbitrary signal sets. Additional bounds are obtained for interference functions independent of the signal set magnitudes or phases. As a recommendation to minimize the worst case performance, the communicator should transmit with a high average probability per signal pM^{-1} for a given fixed {\em sum} \sum S_{m}(f) and \tilde{S}_{m}(f)S_{n}(f)=0, m \neq n , all m,n . However, to weaken the effectiveness of some sub-worst case interference, compared with the worst case. the communicator should transmit with low average probability per signal pM^{-1} and a phase of \sum S_{m}(f) close to \pi . Further investigation of good signal sets is warranted.

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programming Variational Quantum Circuits with Quantum-Train Agent

Programming Variational Quantum Circuits with Quantum-Train ...

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Quantum Communications, Networking, and Computing (QCNC), International Conference on

作者： Chen-Yu Liu Samuel Yen-Chi Chen Kuan-Cheng Chen Wei-Jia Huang Yen-Jui Chang Graduate Institute of Applied Physics National Taiwan University Taipei Taiwan Hon Hai (Foxconn) Research Institute Taipei Taiwan Wells Fargo New York NY USA Department of Electrical and Electronic Engineering Imperial College London London UK Centre for Quantum Engineering Science and Technology (QuEST) Imperial College London London UK Quantum Information Center Chung Yuan Christian University Taoyuan City Taiwan Master Program in Intelligent Computing and Big Data Chung Yuan Christian University Taoyuan City Taiwan

ISBN: (数字)9798331531591

ISBN: (纸本)9798331531607

This study introduces the Quantum-Train Quantum Fast Weight programmer (QT-QFWP) framework, enabling efficient and scalable programming of variational quantum circuits (VQCs) through quantum-driven parameter updates for the classical slow programmer controlling the fast programmer VQC. By optimizing quantum and classical parameter management, QT-QFWP significantly reduces parameters (by 70–90%) compared to Quantum Long Short-Term Memory (QLSTM) and Quantum Fast Weight programmer (QFWP) while maintaining accuracy. Benchmarking on time-series tasks—including Damped Simple Harmonic Motion (SHM), NARMA5, and Simulated Gravitational Waves (GW)—demonstrates superior efficiency and predictive accuracy. QT-QFWP is particularly advantageous for near-term quantum systems, addressing qubit and gate fidelity constraints, enhancing VQC deployment in time-sensitive applications, and expanding quantum computing’s role in machine learning.

关键词： Quantum system Accuracy Computational modeling Qubit Neural networks programming Predictive models Quantum circuit physics Long short term memory

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IMAGING PROPERTIES OF LIGHT SCATTERED BY SEA

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA 1969年第8P1期59卷 891-&页

作者： CHILTON, F JONES, DD TALLEY, WK Theoretical Physics Program Stanford Research Institute Menlo Park California 94025 Department of Applied Science University of California Davis California 95616

We describe a semiphenomenological model of single scattering of light in seawater by particles and turbulence, plus a semianalytic Monte Carlo program for treating the multiple scattering. Ample experimental data were available for wide-angle scattering, but experimental data were not available for scattering at the small angles (10 −3 rad) most relevant for imaging, hence calculations were performed for a variety of parameter values. The results of the Monte Carlo computations were interpretable as simple scaling rules for angular dispersion as a function of range and medium parameters.

关键词： Atmospheric scattering Forward scattering Light properties Light scattering Multiple scattering Particle scattering

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Sound speed estimation using ultrasound image registration

Sound speed estimation using ultrasound image registration

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IEEE International Symposium on Biomedical Imaging, ISBI 2002

作者： Krücker, Jochen F. Fowlkes, J. Brian Carson, Paul L. University of Michigan Department of Radiology United States University of Michigan Applied Physics Program United States

ISBN: (纸本)078037584X

A method for estimating the average speed-of-sound (SOS) in tissue or other materials using automatic registration of electronically steered ultrasound images is presented. A mismatch between the SOS assumed for beam forming and image reconstruction and the actual SOS in the tissue to be imaged can lead to significant de-focusing and geometric distortions of the image. The geometric distortions can be detected by registering multiple, overlapping images steered in different look directions. The average SOS in the field of view can be estimated from the geometric transformation required to register the images. The theoretical basis for SOS estimation using phased array and steered linear array transducers is derived. Simulations show a moderate sensitivity to noise, suggesting that SOS estimations can be accurate enough to improve image quality when used in the image formation process. Examples of SOS estimates in water and tissue-mimicking phantoms show promising results, with errors below 1%. © 2002 IEEE.

关键词： Image enhancement

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