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Walks on Weighted Networks

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Chinese Physics Letters 2007年第2期24卷 577-580页

作者：吴安彩许新建吴枝喜汪映海 Institute of Theoretical Physics Lanzhou University Lanzhou 730000 departamento de fisica da Universidade de Aveiro 3810-193 Aveiro Portugal

We investigate the dynamics of random walks on weighted networks. Assuming that the edge weight and the node strength are used as local information by a random walker. Two kinds of walks, weight-dependent walk and strength-dependent walk, are studied. Exact expressions for stationary distribution and average return time are derived and confirmed by computer simulations. The distribution of average return time and the mean-square displacement are calculated for two walks on the Barrat-Barthelemy-Vespignani （BBV） networks. It is found that a weight-dependent walker can arrive at a new territory more easily than a strength-dependent one.

关键词： EXPLORING COMPLEX NETWORKS EVOLUTION

Orbital angular momentum based intra- and interparticle entangled states generated via a quantum dot source

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先进光子学(英文) 2023年第4期5卷 74-84页

作者： Alessia Suprano Danilo Zia Mathias Pont Taira Giordani Giovanni Rodari Mauro Valeri Bruno Piccirillo Gonzalo Carvacho Nicolo Spagnolo Pascale Senellart Lorenzo Marrucci Fabio Sciarrino Sapienza Universitàdi Roma Dipartimento di FisicaRomaItaly Universite Paris-Saclay UMR 9001Centre for Nanosciences and NanotechnologyCNRSPalaiseauFrance Universitàdi Napoli Federico II Complesso Universitario di Monte Sant’AngeloDipartimento di Fisica“Ettore Pancini”NapoliItaly INFN-Sezione di Napoli NapoliItaly

Engineering single-photon states endowed with orbital angular momentum (OAM) is a powerful toolfor quantum information photonic implementations. Indeed, due to its unbounded nature, OAM is suitable forencoding qudits, allowing a single carrier to transport a large amount of information. Most of the experimentalplatforms employ spontaneous parametric down-conversion processes to generate single photons, evenif this approach is intrinsically probabilistic, leading to scalability issues for an increasing number of *** quantum dots (QDs) have been used to get over these limitations by producing on-demand pure and indistinguishable single-photon states, although only recently they have been exploitedto create OAM modes. Our work employs a bright QD single-photon source to generate a complete set ofquantum states for information processing with OAM-endowed photons. We first study hybrid intraparticleentanglement between OAM and polarization degrees of freedom of a single photon whose preparationwas certified by means of Hong–Ou–Mandel visibility. Then, we investigate hybrid interparticle OAM-based entanglement by exploiting a probabilistic entangling gate. The performance of our approach isassessed by performing quantum state tomography and violating Bell inequalities. Our results pave theway for the use of deterministic sources for the on-demand generation of photonic high-dimensionalquantum states.

关键词： orbital angular momentum quantum dot intraparticle entanglement interparticle entanglement Bell violation

Fiber Cavity Ring Down and Gain Amplification Effect

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Photonic Sensors 2016年第4期6卷 324-327页

作者： Susana SILVA Regina MAGALHAES Rosa Ana PEREZ-HERRERA Manuel LOPEZ-AMO M. B. MARQUES O. FRAZAO IINESC TEC Rua do Campo Alegre 687 4169-007 Porto Portugal dept. de fisica e Astronomia da faculdade de Ciencias da Universidade do Porto Rua do Campo Alegre 687 4169-007 Porto Portugal public University of Navarra Dept. of Electric and Electronic Engineering Campus de Arrosadla Pamplona Spain.

The effect of an erbium-doped fiber amplifier （EDFA） placed inside the fiber ring of a cavity ring down （CRD） configuration is studied. The limitations and advantages of this configuration are discussed, and the study of the ring-down time as a function of the current applied and gain to the EDFA is also presented. In this case, the power fluctuations in the output signal are strongly dependent on the cavity ring-down time with the EDFA gain.

关键词： Cavity ring down EDFA multimode laser optical fibers.

deep reinforcement learning for quantum multiparameter estimation

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Advanced Photonics 2023年第1期5卷 58-70页

作者： Valeria Cimini Mauro Valeri Emanuele Polino Simone Piacentini Francesco Ceccarelli Giacomo Corrielli NicolòSpagnolo Roberto Osellame Fabio Sciarrino Sapienza Universitàdi Roma Dipartimento di FisicaRomaItaly Istituto di Fotonica e Nanotecnologie Consiglio Nazionale delle RicercheMilanoItaly

Estimation of physical quantities is at the core of most scientific research,and the use of quantum devices promises to enhance its *** real scenarios,it is fundamental to consider that resources are limited,and Bayesian adaptive estimation represents a powerful approach to efficiently allocate,during the estimation process,all the available ***,this framework relies on the precise knowledge of the system model,retrieved with a fine calibration,with results that are often computationally and experimentally *** introduce a model-free and deep-learning-based approach to efficiently implement realistic Bayesian quantum metrology tasks accomplishing all the relevant challenges,without relying on any a priori knowledge of the *** overcome this need,a neural network is trained directly on experimental data to learn the multiparameter Bayesian *** the system is set at its optimal working point through feedback provided by a reinforcement learning algorithm trained to reconstruct and enhance experiment heuristics of the investigated quantum ***,we prove experimentally the achievement of higher estimation performances than standard methods,demonstrating the strength of the combination of these two black-box algorithms on an integrated photonic *** work represents an important step toward fully artificial intelligence-based quantum metrology.

关键词： quantum sensing integrated photonics machine learning for metrology

EFFECTIVE NETWORKS FOR REAL-TIME DISTRIBUTED PROCESSING

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Journal of Systems Science & Complexity 2011年第1期24卷 39-50页

作者： Gonzalo TRAVIESO Luciando da Fontoura COSTA Instituto de fisica de Sao Carlos Universidade de Sao Paulo Av. do Trabalhador SSo-Carlensc 400 13566 - 590 Sao Carlos SP Brazil.

这份报纸把复杂网络的概念和方法用于模型的开发和由在许可的交货介绍上面的界限的分布式的即时系统与计算结果包预定的主人奴隶的模拟。二个代表性的互联模型被考虑：一致地。

关键词：分布式实时系统复杂网络分布式处理计算结果应用程序数据包随机和随机大

Magnetizations and magneto-transport properties of Ni-doped PrFeO_3 thin films

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Chinese Physics B 2014年第4期23卷 608-615页

作者： Feroz A.Mir S.K.Sharma Ravi Kumar University Science Instrumentation Center University of Kashmir Instituto de fisica Gleb Wataghin Universidade Estadual de Campinas (UNICAMP) CMSE National Institute of Technology

The present study reports the magnetizations and magneto-transport properties of PrFel_xNixO3 thin films grown by pulsed laser ablation technique on LaA103 snbstrates. From DC M/H plots of these films, weak ferromagnetism or ferrimagnetism behaviors are observed. With Ni substitution, reduction in saturation magnetization is also seen. With Ni doping, variations in saturation field （Hs）, coercive field （Hc）, Weiss temperature （0）, and effective magnetic moment （Pelf） are seen. A small change of magnetoresitance with application of higher field is observed. Various essential parameters like density of state （Nf） at Fermi level, Mott＇s characteristic temperature （To）, and activation energy （Ea） in the presence of and in the absence of magnetic field are calculated. The present observed magnetic properties are related to the change of Fe-O bond length （causing an overlap between the oxygen p orbital and iron d orbital） and the deviation of the Fe-O-Fe angle from 180~. Reduction of magnetic domain after Ni doping is also explored to explain the present observed magnetic behavior of the system. The influence of doping on various transport properties in these thin films indicates a distortion in the lattice structure and single particle band width, owing to stress-induced reduction in unit cell volume.

关键词： thin films magnetization ferromagnetism ferrimagnetism magneto-transport and distortion

Thermal conductivity of glasses: first-principles theory and applications

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npj Computational Materials 2023年第1期9卷 1253-1274页

作者： Michele Simoncelli Francesco Mauri Nicola Marzari Theory of Condensed Matter Group of the Cavendish Laboratory University of CambridgeCambridgeUK Dipartimento di fisica Universitàdi Roma La SapienzaRomaItaly Theory and Simulation of Materials(THEOS)and National Centre for Computational design and Discovery of Novel Materials(MARVEL) École Polytechnique Fédérale de LausanneLausanneSwitzerland

Predicting the thermal conductivity of glasses from first principles has hitherto been a very complex *** established Allen-Feldman and Green-Kubo approaches employ approximations with limited validity—the former neglects anharmonicity,the latter misses the quantum Bose-Einstein statistics of vibrations—and require atomistic models that are very challenging for first-principles ***,we present a protocol to determine from first principles the thermal conductivityκ(T)of glasses above the plateau(i.e.,above the temperature-independent region appearing almost without exceptions in theκ(T)of all glasses at cryogenic temperatures).The protocol combines the Wigner formulation of thermal transport with convergence-acceleration techniques,and accounts comprehensively for the effects of structural disorder,anharmonicity,and Bose-Einstein *** validate this approach in vitreous silica,showing that models containing less than 200 atoms can already reproduceκ(T)in the macroscopic *** discuss the effects of anharmonicity and the mechanisms determining the trend ofκ(T)at high temperature,reproducing experiments at temperatures where radiative effects remain negligible.

关键词： glasses conductivity harmonic

Strong emissions of blue-yellow-red regions of La and Ti modified KNaNbO_(3) ferroelectric ceramics

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Journal of Advanced Ceramics 2015年第3期4卷 183-189页

作者： M.D.DURRUTHY-RODRIGUEZ M.HERNANdeZ-GARCIA J.PORTELLES J.FUENTES M.A.HERNANdeZ-LANDAVERde M.RAMIREZ CARDONA J.M.YANEZ-LIMON departamento de fisica Aplicada Instituto de CiberneticaMatematica y FisicaCITMA15#551VedadoLa HabanaCP 10400Cuba Facultad de fisica Universidad de La HabanaSan Lazaro y LVedadoLa HabanaCP 10400Cuba CINVESTAV-Unidad Queretaro IPNLibramiento Norponiente 2000Fracc.Real de JuriquillaCP 76230QueretaroMexico Centro de Investigaciones en Ciencias de la Tierra y Materiales Universidad Autonoma del Estado de HidalgoMexico

In this work,the results of the study on the optical properties of the perovskite structure ABO3 with La^(3+) substitution for ions K^(+) and Na^(+) in the A site and Ti^(4+) substitution for ion Nb^(5+) in the B site are *** ceramics were sintered at 1100℃ and 1190℃ and formed at 10 MPa and 80 *** ceramics were obtained with 94% of the theoretical *** piezoresponse force microscopy(PFM)showed needle-shaped grains with a size of 30 nm for the samples formed at 10 MPa at both sintering ***,the high temperature and high pressure used in formation reduced the energy of the band gap(Eg)from 3.36 to 3.09 *** emissions to 2.19,1.86,2.5,and 2.31 eV were obtained by exciting the samples at 325,373,457,and 500 nm,respectively;these emissions corresponded to blue-yellow-red regions of the visible spectrum.

关键词： emission spectra condense matter ferroelectric materials band structure X-ray diffraction(XRD)

Is Brenner＇s Modification to the Classical Navier-Stokes Equations Able to describe Sound Propagation in Gases？

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Chinese Physics Letters 2008年第4期25卷 1355-1358页

作者： W. Marques Jr. departamento de fisica Universidade Federal do Parana Calxa Postal 19044 81531-990 Curitiba Brazil

We analyse the problem concerning the propagation of sound waves in gases by using the modified hydrodynamic theory proposed recently by Brenner for single-component fluids. The modifications introduced by Brenner are based on his proposal that the translational momentum in fluid motion is not given by the mass flux. Comparison of the sound propagation results derived from Brenner＇s theory with available experimental data for monatomic gases shows that this modified continuum theory is unable to describe the acoustic measurements not even in the low-frequency limit, a result that from our point of view makes Brenner＇s proposal questionable.

关键词： Modification Classical Navier-Stokes Equations Able