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Table of Content

    20 April 2016 Volume 35 Issue 4
      
    Quantum phase transitions and quantum entanglement
    College Physics. 2016, 35(4):  1-1. 
    Abstract ( 1317 )   PDF (560KB) ( 1666 )  
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    Quantum entanglement,as an inherent nonlocal correlation,has become one of the important available sources,and was widely applied in many fields. The quantum phase transition in strongly correlated systems,as an important phenomenon,is still a remarkable focus in condensed matter physics. In the present paper,the conception,the criteria,and the measurement of entanglement are introduced and discussed. Then,the quantum phase transitions in a representative model are investigated,and how to describe the quantum phase transitions by the quantum entanglement is also discussed. It is found that the quantum entanglement plays a key role in quantum phase transitions.
    著者文摘
    The chaotic behavior in a conservative elliptical pendulum system under periodic perturbation
    . 2016, 35(4):  7-7. 
    Abstract ( 937 )   PDF (438KB) ( 872 )  
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    The motion equations of an elliptical pendulum system under periodic perturbation are derived by using the generalized Lagrange equation. The equations are solved numerically to investigate the process of the deformation,distortion,split of the invariant torus and the chaos. Moreover,the influences of the perturbation frequency and the mass parameter on the chaotic behavior are discussed through analyzing the maximum Lyapunov exponent.
    The transition radiation explanation about the frequency conversion formula of light and the essence of photon concept
    . 2016, 35(4):  11-11. 
    Abstract ( 1449 )   PDF (331KB) ( 678 )  
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    Combining the mass energy relation,mass velocity relation,photon hypothesis and transition radiation hypothesis,the frequency conversion formula of light is deduced. The transition radiation frequency formula of a free particle is obtained in the case of the speed being not fast. Finally,a simple introduction about the essence of photon concept is given.
    Analytical solution of equation of mathematical physics in the waveguide system loaded with nearly-zero-index-metamaterials and simulation by using COMSOL
    . 2016, 35(4):  15-15. 
    Abstract ( 1231 )   PDF (1242KB) ( 768 )  
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    The transmission characteristics of electromagnetic wave in the waveguide system,filled with nearly- zero- index- metamaterials and loaded with dielectric defects,belongs to the problem of Helmholtz equation with non- homogeneous boundary value in the source of the method of mathematics. It can be solved by a variety of methods for solving partial differential equations. In this paper,the separation variables method is used for solving two typical examples. Furthermore,the software named COMSOL multi- physics,which is based on the finite element method,is used for simulation,and the correctness of theoretical analysis is certified. For more general problems,numerical calculation and simulation by COMSOL are more commonly applied.
    The Madelung constant of two-dimensional ion crystal
    . 2016, 35(4):  19-19. 
    Abstract ( 1590 )   PDF (247KB) ( 1431 )  
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    The analytical expression of Madelung constant of two- dimensional square and hexagon ion crystal is derived from the infinite summation technique and asymptotic expansion method.
    Two equivalent resistance formulas of 3D △ × n network
    . 2016, 35(4):  22-22. 
    Abstract ( 1435 )   PDF (412KB) ( 873 )  
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    Under various conditions,an equivalent resistance of 3D △ × n network is studied. By establishing model of differential equations and matrix transformation in terms of network analysis,we have found two equivalent resistance formulas between two remote nodes of 3D △ × n network. The equivalent resistance can be specifically discussed and confirmed.
    Evaluation of infinite sum by residue theorem and its generalization
    . 2016, 35(4):  26-26. 
    Abstract ( 1788 )   PDF (328KB) ( 1182 )  
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    We discuss the method of summation of some infinite series by the residue theorem,then extend to infinite series containing trigonometric function and give rigorous proofs. Finally,we illustrate the correctness of the present results and compare the result of an example by using two different methods. From an example,we see the effectiveness of residue theorem in the simplification of infinite series.
    Young's modulus measurement for a wire with wedge interference method
    . 2016, 35(4):  30-30. 
    Abstract ( 1419 )   PDF (918KB) ( 905 )  
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    A wedge interference device is designed and its wedge- angle can be changed freely. The mini- elongation of the metal wire can be measured precisely by the device,so that the Young's modulus for steel can be obtained.
    Comparison of the multi-point measuring method and the least deviation angular method in the measurement of dispersion relation
    . 2016, 35(4):  33-33. 
    Abstract ( 1178 )   PDF (429KB) ( 473 )  
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    Based on the multi- point measurements,the refractive index is fitted from the data of non- least deviation angular by the nonlinear- fitting of Origin( software),to gain the dispersion relation of sample. The multiple point measuring method can be used to improve the degree of accuracy of dispersion relation of sample and achieve higher precision measurement than the least deviation angular method,by comparing multiple point measuring method and the least deviation angular method of fitting results of dispersion equation.
    GONG Zutong pioneering contributions in the optical industry of China's military
    . 2016, 35(4):  38-38. 
    Abstract ( 964 )   PDF (553KB) ( 924 )  
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    Based on the original journal articles,the science contribution of the modern optics expert Gong Zutong in applied optics industry is studied. It is concluded that Gong Zutong specialized in application of optical design and optical glass,designed and produced China's first military binocular "officially telescope "telescope,designed and successful trial machine gun sight and reflection measured 80 cm telescope; made China's first aircraft infrared night vision; crucible melting China's first optical glass,created a Chinese modern optical design,optical instrument manufacturing night vision technology and optical glass industry precedent. He spent his whole life dedicated to the building of national defense of the motherland,especially for the development of applied optics China made important contributions to the cause.
    Karl Ferdinand Braun's some important contributions to physics
    College Physics. 2016, 35(4):  43-43. 
    Abstract ( 1255 )   PDF (755KB) ( 1370 )  
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    The brief biography of Karl Ferdinand Braun is recounted. The contributions of his discovery of some crystals conducted electric currents in only one direction,invention of the cathode- ray oscilloscope and improvement the wireless telegraphy are reviewed. The factors of his regarding innovation as his own responsibility,insisting going his owner way,and giving full play to his professional knowledge are summarized.
    著者文摘
    Investigations on the bound states of delta potential wells in one-dimensional atomic chain using Fourier transform
    . 2016, 35(4):  49-49. 
    Abstract ( 1078 )   PDF (294KB) ( 415 )  
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    Fourier- transform method is used for solving Schrdinger equation with delta potential wells in one- dimensional atomic chain. The formula describing the energy levels of the atomic chain is obtained. The method used in this paper is a valuable theoretical reference for studying the energy- level structure of micro- material.
    The faraday wave of the low-viscosity silicon oil excited by vertical oscillation
    College Physics. 2016, 35(4):  52-52. 
    Abstract ( 1239 )   PDF (1385KB) ( 888 )  
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    The faraday wave of the low- viscosity silicon oil excited by vertical sinusoidal oscillation at low frequencies is studied from experimental and theoretical aspects. A series of clear standing wave patterns( 2- crest pattern to 8- crest pattern),especially the stars- shaped one have been observed. Systematic study shows that the waves belong to subharmonic resonance with frequency of half the excitation frequency. The dispersion relation of the observed surface wave can be described by the inviscid theory and gravity is the dominant restoring force. The standing wave patterns are classified by the number of the wave crest. In experimenting with the increase of the driving frequency,the wave patterns become complicated and show up as the increase of the wave crest number,while the corresponding amplitude decreases. This experimental phenomenon is explained well by analyzing the wavelengths and excitation threshold of the different patterns of the standing waves. The study in this paper has certain reference significance to the research of the surface wave of a fluid in a rigid container due to external excitation.
    The high evaluation in Born's letters on YANG Li-ming's research work
    College Physics. 2016, 35(4):  60-60. 
    Abstract ( 988 )   PDF (670KB) ( 687 )  
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    YANG Li-ming was the third Chinese doctor supervised by Max Born,and also the last Chinese pupil of Born. From 1950 to 1951,Born wrote many letters to very known physicists,such as Bohr,Heisenberg,Fermi,Wigner,Jordan,and some important periodicals,promoted and gave high evaluation on the research results which were made by YANG Li-ming. One could feel the intense sense of responsibility of Born to his pupil,and his appreciation to the Chinese pupil when one reading these letters carefully. These letters which were not known,are the valuable and moving archives,and they formed a clue which connected Chinese physics to the world. The letters need to be farther researched by our researchers who working on the history of physics,they also need to know and pay more concerns by the society of Chinese physics.