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Emission properties of nanolasers during the transition to lasing

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Light(Science & Applications) 2014年第1期3卷 92-99页

作者： Weng W Chow Frank Jahnke Christopher Gies Sandia National laboratories AlbuquerqueNM 87185-1086USA Institute for theoretical Physics University of Bremen28334 BremenGermany

This review addresses ongoing discussions involving nanolaser experiments,particularly those related to thresholdless lasing or few-emitter devices.A quantum-optical(quantum-mechanical active medium and radiation field)theory is used to examine the emission properties of nanolasers under different experimental *** active medium is treated as inhomogeneously broadened semiconductor quantum dots embedded in a quantum well,where carriers are introduced via current *** are made between a conventional laser and a nanolaser with a spontaneous emission factor of unity,as well as a laser with only a few quantum dots providing the *** is found that the combined exploration of intensity,coherence time,photon autocorrelation function and carrier spectral hole burning can provide a unique and consistent picture of nanolasers in the new regimes of laser operation during the transition from thermal to coherent ***,by reducing the number of quantum dots in the optical cavity,a clear indication of non-classical photon statistics is observed before the single-quantum-dot limit is reached.

关键词： nanolasers optoelectronics photon statistics quantum light sources quantum optics semiconductor quantum dots thresholdless lasing

Deep material network via a quilting strategy: visualization for explainability and recursive training for improved accuracy

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npj Computational Materials 2023年第1期9卷 1023-1038页

作者： Dongil Shin Ryan Alberdi Ricardo A.Lebensohn Rémi Dingreville Center for Integrated Nanotechnologies Sandia National LaboratoriesAlbuquerqueNM 87185USA Simulation Modeling Sciences Sandia National LaboratoriesAlbuquerqueNM 87185USA theoretical Division Los Alamos National LaboratoryLos AlamosNM 87845USA

Recent developments integrating micromechanics and neural networks offer promising paths for rapid predictions of the response of heterogeneous materials with similar accuracy as direct numerical *** deep material network is one such approaches,featuring a multi-layer network and micromechanics building blocks trained on anisotropic linear elastic *** trained,the network acts as a reduced-order model,which can extrapolate the material’s behavior to more general constitutive laws,including nonlinear behaviors,without the need to be ***,current training methods initialize network parameters randomly,incurring inevitable training and calibration ***,we introduce a way to visualize the network parameters as an analogous unit cell and use this visualization to“quilt”patches of shallower networks to initialize deeper networks for a recursive training *** result is an improvement in the accuracy and calibration performance of the network and an intuitive visual representation of the network for better explainability.

关键词： networks Deep network

PREDICTION OF DIELECTRIC DISPERSION FOR LEAD BASED PEROVSKITES AND STUDY OF LOCAL DIELECTRIC RESPONSE IN 0.75Pb(Mg_(1/3)Nb(2/3))O_(3)-0.25PbTiO_(3)

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Journal of Advanced Dielectrics 2012年第2期2卷 121-126页

作者： ILYA GRINBERG HIROYUKI TAKENAKA YOUNG-HAN SHIN ANDREW M.RAPPE the makineni theoretical laboratories Department of Chemistry University of PennsylvaniaPhiladelphia PA 19104-6323USA Multiscale Materials Modeling Lab Department of Physics University of UlsanUlsan 680-749Korea

Relaxors exhibit unique dielectric response properties such as diffuse phase transitions and strong dispersion of the dielectric *** origin of these properties is still not fully ***,we review our work on usingfirst-principles-based methods to elucidate the connections between composition,local structure and dynamics in Pb-based relaxors.

关键词： Relaxor dielectric response dynamics relaxation time

Intermittency and Thermalization in Turbulence

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Chinese Physics Letters 2010年第5期27卷 152-155页

作者：朱建州 MarkTaylor theoretical Division and CNLS MS B258 Los Alamos National Laboratory Los Alamos NM 87545 U.S.A. CCIM MS 0370 Sandia National Laboratories Albuquerque NM 87185 U.S.A.

A dissipation rate, which grows faster than any power of the wave number in Fourier space, may be scaled to lead a hydrodynamic system to actually or potentially converge to its Galerkin truncation. Actual convergence here means the asymptotic truncation at a finite wavenumber kc above which modes have no dynamics; and, we define potential convergence for the truncation at kG which, however, grows without bound. Both types of convergence can be obtained with the dissipation rate μ[cosh（k/kc） - 1] that behaves as k2 （newtonian） and exp{k/kc} for small and large k/kc respectively. Competing physics of cascade, thermalization and dissipation are discussed for numerical Navier-Stokes turbulence, emphasizing the intermittency growth issue.

关键词： dissipation rate dissipation grows

Training data selection for accuracy and transferability of interatomic potentials

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npj Computational Materials 2022年第1期8卷 1795-1803页

作者： David Montes de Oca Zapiain Mitchell A.Wood Nicholas Lubbers Carlos ZP.ereyra Aidan P.Thompson Danny Perez Sandia National laboratories AlbuquerqueNM87185USA Computer Computationaland Statistical Sciences DivisionLos Alamos National LaboratoryLos AlamosNM87545USA Mechanical and Aerospace Engineering University of California DavisDavisCA95616USA theoretical Division Los Alamos National LaboratoryLos AlamosNM87545USA

Advances in machine learning(ML)have enabled the development of interatomic potentials that promise the accuracy of first principles methods and the low-cost,parallel efficiency of empirical ***,ML-based potentials struggle to achieve transferability,i.e.,provide consistent accuracy across configurations that differ from those used during *** order to realize the promise of ML-based potentials,systematic and scalable approaches to generate diverse training sets need to be *** work creates a diverse training set for tungsten in an automated manner using an entropy optimization ***,multiple polynomial and neural network potentials are trained on the entropy-optimized dataset.A corresponding set of potentials are trained on an expert-curated dataset for tungsten for *** models trained to the entropy-optimized data exhibited superior transferability compared to the expert-curated ***,the models trained to the expert-curated set exhibited a significant decrease in performance when evaluated on out-of-sample configurations.

关键词： entropy transfer configuration

Negative-Resistance Characteristics Analysis of Poly-Silicon Resistors Formed on the Flow Sensor

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稀有金属材料与工程 2006年第A3期35卷 490-491页

作者： DianzhongWen Major laboratories of Integrated Circuits Heilongjiang University Harbin 150080 China Major laboratories of Electronic Engineering Heilongjiang University Harbin 150080 China

In this paper we put forward a new concept about effective trapping center concentration N^e_T which is decreasing with the trapped charge Q corresponding to index movement,based on that,we discuss theⅠ-Ⅴand temperature characteristics of polysilicon *** new concept presents ideal theoretical interpretion for the originally observed current-voltage negative-resistance characteristics of polysilicon resistors formed on the flow sensor,and also for poly-silicon film resistors. The final results agree well with the theoretical current-voltage characteristics.

关键词： poly-silicon resistor trapping center negative-resistance grain boundary

AN AUTO-TRACKING PARABOLIC SENSING ANTENNA WITH DUAL-MODE ARCHIMEDES-SPIRAL FEED

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Journal of Electronics(China) 1987年第1期4卷 62-68页

作者：周文甫王国英章日荣 Shijiazhuang Communications laboratories

In this paper, an introduction of the auto-tracking parabolic sensing antenna with dual-modearchimedes-spiral feed is given. theoretical analysis, calculation and experiment have also been made. Thetheoretical values ... 详细信息

关键词： mode AN AUTO-TRACKING PARABOLIC SENSING ANTENNA WITH DUAL-MODE ARCHIMEDES-SPIRAL FEED

Performance of two complementary machine-learned potentials in modelling chemically complex systems

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npj Computational Materials 2023年第1期9卷 1008-1022页

作者： Konstantin Gubaev Viktor Zaverkin Prashanth Srinivasan Andrew Ian Duff Johannes Kästner Blazej Grabowski Institute for Materials Science University of StuttgartPfaffenwaldring 5570569 StuttgartGermany Institute for theoretical Chemistry University of StuttgartPfaffenwaldring 5570569 StuttgartGermany Scientific Computing Department STFC Daresbury LaboratoryWarrington WA44ADUK Present address:NEC laboratories Europe GmbH Kurfürsten-Anlage 3669115 HeidelbergGermany

Chemically complex multicomponent alloys possess exceptional properties derived from an inexhaustible compositional *** complexity however makes interatomic potential development *** explore two complementary machine-learned potentials—the moment tensor potential(MTP)and the Gaussian moment neural network(GM-NN)—in simultaneously describing configurational and vibrational degrees of freedom in the Ta-V-Cr-W alloy *** models are equally accurate with excellent performance evaluated against *** achieve root-mean-square-errors(RMSEs)in energies of less than a few meV/atom across 0 K ordered and high-temperature disordered configurations included in the *** for compositions not in training,relative energy RMSEs at high temperatures are within a few meV/***-temperature molecular dynamics forces have similarly small RMSEs of about 0.15 eV/Åfor the disordered quaternary included in,and ternaries not part of *** achieve faster convergence with training size;GM-NNs are faster in *** learning is partially beneficial and should be complemented with conventional human-based training set generation.

关键词： alloy faster complex

Variable-order fracture mechanics and its application to dynamic fracture

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npj Computational Materials 2021年第1期7卷 248-255页

作者： Sansit Patnaik Fabio Semperlotti School of Mechanical Engineering Ray W.Herrick LaboratoriesPurdue UniversityWest LafayetteIN 47907USA

This study presents the formulation,the numerical solution,and the validation of a theoretical framework based on the concept of variable-order mechanics and capable of modeling dynamic fracture in brittle and quasi-brittle *** specifically,the reformulation of the elastodynamic problem via variable and fractional-order operators enables a unique and extremely powerful approach to model nucleation and propagation of cracks in solids under dynamic *** resulting dynamic fracture formulation is fully evolutionary,hence enabling the analysis of complex crack patterns without requiring any a priori assumption on the damage location and the growth path,and without using any algorithm to numerically track the evolving crack *** evolutionary nature of the variable-order formalism also prevents the need for additional partial differential equations to predict the evolution of the damage field,hence suggesting a conspicuous reduction in complexity and computational ***,the variable-order formulation is naturally capable of capturing extremely detailed features characteristic of dynamic crack propagation such as crack surface roughening as well as single and multiple *** accuracy and robustness of the proposed variableorder formulation are validated by comparing the results of direct numerical simulations with experimental data of typical benchmark problems available in the literature.

关键词： formulation dynamic hence