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Extremal eigenvalues of measure differential equations with fixed variation

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Science china Mathematics 2010年第10期53卷 2573-2588页

作者： ZHANG MeiRong 1,2 1 department of Mathematical Sciences,tsinghua university,beijing 100084,china 2 Zhou Pei-Yuan center for Applied Mathematics,tsinghua university,beijing 100084,china 1. department of Mathematical Sciences Tsinghua University Beijing 100084 China2. Zhou Pei-Yuan Center for Applied Mathematics Tsinghua University Beijing 100084 China

In this paper we will study eigenvalues of measure differential equations which are motivated by physical problems when physical quantities are not absolutely *** taking Neumann eigenvalues of measure differential equations as an example,we will show how the extremal problems can be completely solved by exploiting the continuity results of eigenvalues in weak* topology of measures and the Lagrange multiplier rule for nonsmooth *** results can give another explanation for extremal eigenvalues of SturmLiouville operators with integrable potentials.

关键词： measure differential equation eigenvalue extremal value weak* topology Frechét derivative sub-differential

The geometrical structure, electronic structure and magnetism of bimetallic Au_nM_2 (n=1, 2; M=Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd) clusters

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Science china(physics,Mechanics & Astronomy) 2009年第7期52卷 1011-1020页

作者： GU Juan1,2, WANG ShanYing2 & GOU BingCong1 1 department of physics, beijing Institute of Technology, beijing 100081, china 2 department of physics, tsinghua university, beijing 100084, china department of physics Beijing Institute of Technology Beijing 100081 China department of physics Tsinghua University Beijing 100084 China

The geometrical structure, stability, magnetism, and electronic structure of bimetallic clusters AuM2 and Au2M2, where M are 4d transition metal elements, are investigated systematically by using the first-principles method based on density functional theory. The calculation results show that there is a large amount of low-energy isomers with the very similar structure. AuM2 and Au2M2 clusters display dramatic magnetism. The magnetic moment of the 4d element is either enhanced or weakened with respect to the bulk value, which is largely dependent on the orbital exchange-splitting.

关键词： density functional theory first-principles cluster electronic structure magnetism

Two-fluid Dynamics in Clusters of Galaxies

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Chinese Journal of Astronomy and astrophysics 2005年第1期5卷 6-20页

作者： Yu-Qing LouNational Astronomical Observatories, Chinese Academy of Sciences, beijing 100012department of physics & tsinghua center for astrophysics (THCA), tsinghua university, beijing 100084 department of Astronomy and astrophysics, The university of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 USA National Astronomical Observatories Chinese Academy of Sciences Beijing 100012

We develop a theoretical formulation for the large-scale dynamics of galaxy clusters involving two spherical 'isothermal fluids' coupled by their mutual gravity and derive asymptotic similarity solutions analytically. One of the fluids roughly approximates the massive dark matter halo, while the other describes the hot gas, the relatively small mass contribution from the galaxies being subsumed in the gas. By properly choosing the self-similar variables, it is possible to consistently transform the set of time-dependent two-fluid equations of spherical symmetry with self-gravity into a set of coupled nonlinear ordinary differential equations (ODEs). We focus on the analytical analysis and discuss applications of the solutions to galaxy clusters.

关键词： dark matter - hydrodynamics - ISM: general - galaxies: clusters -outflows winds - shocks

Density-functional formula for strongly correlated systems

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Progress in Natural Science:Materials International 2005年第5期15卷 395-401页

作者： WANG Huaiyu1*, HAN Rushan2 and CHEN Nanxian1(1. department of physics, tsinghua university, beijing 100084, china 2. department of physics, Peking university, beijing 100871, china) department of physics Tsinghua University Beijing 100084 China department of physics Peking University Beijing 100871 China

Density functional method is applied for strongly correlated systems. Based on the assumption that the systems are composed of electrons in singly-occupied orbitals and those in doubly-occupied orbitals, a set of self-consistent equations are obtained by standard variation procedure. The equations consist of two parts. One part is to solve the wave functions of the electrons in singly-occupied orbitals and the other is to solve the wave functions of the electrons in doubly-occupied orbitals. The physical meanings of the terms appearing in the equations are discussed.

关键词： density-functional theory strongly correlated systems doubly-occupied orbital two-particle wave function self-consistent equations.

A scheme to implement the Deutsch-Josza algorithm on a superconducting charge-qubit quantum computer

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Progress in Natural Science:Materials International 2006年第6期16卷 594-599页

作者： HUO Wenyi and LONG Guilu (Key Laboratory for Quantum Information and Measurements, and department of physics, tsinghua university, beijing 100084, china Key Laboratory for Atomic and Molecular NanoSciences, tsinghua university, beijing 100084, china) [a]Key Laboratory for Quantum Information and Measurements and Department of Physics Tsinghua University Bejjing China [b]Key Laboratory for Atomic and Molecular NanoSciences Tsinghua University Bejing China

We have studied the implementation of the Deutsch-Josza quantum algorithm in a superconducting charge-qubit quantum computer. Different from previous studies, we have used the inductance coupled system of You et al. The detailed pulse sequences have been designed for the four possible functions in a 2-qubit system. The result is generalized to an arbitrary n-qubit system. This scheme will be useful for practical implementation of the algorithm.

关键词： superconducting quantum computer Deutsch-Josza algorithm.

Calculation of light emission in sonoluminescence

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Science china(physics,Mechanics & Astronomy) 2009年第4期52卷 593-601页

作者： LI ChaoHui1 & AN Yu1,2 1 department of physics,tsinghua university,beijing 100084,china 2 Institute of Acoustics,Chinese Academy of Sciences,beijing 100190,china department of physics Tsinghua University Beijing 100084 China Institute of Acoustics Chinese Academy of Sciences Beijing 100190 China

We modify a uniform model of single bubble sonoluminescence,in which heat diffusion,water vapor diffusion and chemical reactions are included to describe the bubble dynamics,and the processes of electron-atom bremsstrahlung,electron-ion bremsstrahlung and recombination radiation,radiative attachment of electrons to atoms and molecules,line emissions of OH radicals and Na atoms are taken into account to calculate the light emission. With this model,we compute the light pulse width,the photon number per flash,the continuum and line spectra and the gas species as the products of chemical reactions,and try to compare with all the experimental data available. We obtain good agreement with the observations of Ar and Xe bubbles in many cases,but fail to match the experimental data of the photon number per flash. We also find that for He bubble the computed photon number is always too small to interpret the observations.

关键词： sonoluminescence bremsstrahlung radiative attachment line spectrum collision broadening

Anomalous magnetotransport in LaMn_(1-x)Te_xO_3

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Science china(physics,Mechanics & Astronomy) 2009年第7期52卷 987-992页

作者： TAN GuoTai1,2, CHEN ZhengHao3 & ZHANG XiaoZhong4,5 1 Key Laboratory of Beam Technology & Materials Modification of the Ministry of Education, Institute of Low Energy Nuclear physics, beijing Normal university, beijing 100875, china 2 beijing Radiation center, beijing 100875, china 3 Laboratory of Optical physics, Institute of physics, Chinese Academy of Sciences, beijing 100080, china 4 Key Laboratory of Advanced Materials of the Ministry of Education, department of Materials Science and Engineering, tsinghua university, beijing 100084, china 5 beijing National center for Electron Microscopy, tsinghua university, beijing 100084, china 1. Key Laboratory of Beam Technology & Materials Modification of the Ministry of Education Institute of Low Energy Nuclear Physics Beijing Normal University Beijing 100875 China 2. beijing Radiation center Beijing 100875 China 3. Laboratory of Optical physics Institute of Physics Chinese Academy of Sciences Beijing 100080 China 4. Key Laboratory of Advanced Materials of the Ministry of Education Department of Materials Science and Engineering Tsinghua University Beijing 100084 China 5. beijing National center for Electron Microscopy Tsinghua University Beijing 100084 China

The LaMn1-xTexO3+δ (x=0.1, 0.2, 0.3) were synthesized using solid-state reaction method for the first time. X-ray photoemission spectrum (XPS) shows that in the samples the Te ions have a valence of Te4+, and Mn3+ ions are partly converted into Mn2+ and Mn4+ due to the excess oxygen and Te doping. The magnetotransport associated with Mn2+, Mn3+ and Mn4+ was investigated. The experimental results show that the samples are insulator at 0 T when the amount of Mn3+ is much larger or less than the sum of Mn2+ and Mn4+; by contrast, the samples display metal to insulator transition with increasing temperature when the amount of Mn3+ is close to the sum of Mn2+ and Mn4+. These anomalous magnetotransport behaviors were analyzed in the frame of the double-exchange (DE) mechanism.

关键词： colossal magnetoresistance La-Te-Mn-O magnetotransport

Multiparty quantum secret sharing of classical and quantum messages

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Progress in Natural Science:Materials International 2007年第1期17卷 26-31页

作者： CHEN Pan, DENG Fuguo and LONG Guilu ( Key Laboratory for Quantum Information and Measurements, and department of physics, tsinghua university, beijing 100084, china Key Laboratory of Beam Technology and Material Modification, MOE, Institute of Low Energy Nuclear physics, and department of Material Science and Engineering, beijing Normal university, beijing 100875, china beijing Radiation center, beijing 100875, china Key Laboratory for Atomic and Molecular Nano-Sciences, tsinghua university, beijing 100084, china) [a]Key Laboratory for Quantum Information and Measurements and Department of Physics Tsinghua University Beijing China [b]Key Laboratory of Beam Technology and Material Modification MOE Institute of Low Energy Nuclear Physics and Department of Material Science and Engineering Beijing Normal University Beijing China [c]beijing Radiation center Beijing China [d]Key Laboratory for Atomic and Molecular Nano-Sciences Tsinghua University Beijing China

A scheme for multiparty quantum secret sharing of classical and quantum messages is proposed by using entanglement swapping. This scheme can distribute not only the classical information but also the quantum informati... 详细信息

关键词： quantum secret sharing classical message quantum message EPR pair.

Novel Experimental Method in the Study of Double Rydberg States by Laser Resonance Excitation

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Chinese Journal of Lasers 1997年第2期B6卷 141-146页

作者： XU Xiangyuan HUANG Wen(department of Modern Applied physics, tsinghua university, beijing 100084, china) tsinghua Univ Beijing China

We describe a novel experimental method by introducing sequential ionization with a pulsed and a strong constant electric field in a time-of-flight mass spectrometer. This method is applied to study laser-excited double Rydberg states of neutral ytterbium atom, with the ionic resonance background in the spectrum of the double Rydberg states of Yb being greatly suppressed.

关键词： atomic double Rydberg state laser excitation field ionization