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Volume 26 Issue 2
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GENERAL
 Select Approximate Symmetry Reduction to the Perturbed One-Dimensional Nonlinear Schrödinger Equation JIA Man, WANG Jian-Yong, LOU Sen-Yue, Chin. Phys. Lett. 2009, 26 (2): 020201 .   DOI: 10.1088/0256-307X/26/2/020201 Abstract   PDF(pc) (188KB) ( 1832 ) The one-dimensional nonlinear Schrödinger equation with a perturbation of polynomial type is considered. Using the approximate symmetry perturbation theory, the approximate symmetries and approximate symmetry reduction equations are obtained.
 Select N-Soliton Solution of a Generalized Hirota-Satsuma Coupled KdV Equation and Its Reduction WU Jian-Ping, GENG Xian-Guo, ZHANG Xiao-Lin Chin. Phys. Lett. 2009, 26 (2): 020202 .   DOI: 10.1088/0256-307X/26/2/020202 Abstract   PDF(pc) (228KB) ( 1074 ) Based on the Hirota method and the perturbation technique, the N-soliton solution of a generalized Hirota-Satsuma coupled KdV equation is obtained. Further, the N-soliton solution of a complex coupled KdV equation is given by reducing.
 Select Quantum Partial Searching Algorithm of a Database with Several Target Items ZHONG Pu-Cha, BAO Wan-Su, WEI Yun Chin. Phys. Lett. 2009, 26 (2): 020301 .   DOI: 10.1088/0256-307X/26/2/020301 Abstract   PDF(pc) (215KB) ( 962 ) Choi and Korepin [{Quantum Information Processing} 6(2007)243] presented a quantum partial search algorithm of a database with several target items which can find a target block quickly when each target block contains the same number of target items. Actually, the number of target items in each target block is arbitrary. Aiming at this case, we give a condition to guarantee performance of the partial search algorithm to be performed and the number of queries to oracle of the algorithm to be minimized. In addition, by further numerical computing we come to the conclusion that the more uniform the distribution of target items, the smaller the number of queries.
 Select An Alternative Method for Calculating Bound-State of Energy Eigenvalues of Klein-Gordon for Quasi-exactly Solvable Potentials Eser Olgar Chin. Phys. Lett. 2009, 26 (2): 020302 .   DOI: 10.1088/0256-307X/26/2/020302 Abstract   PDF(pc) (171KB) ( 809 ) We obtain the bound-state energy of the Klein--Gordon equation for some examples of quasi-exactly solvable potentials within the framework of asymptotic iteration method (AIM). The eigenvalues are calculated for type-1 solutions. The whole quasi-exactly solvable potentials are generated from the defined relation between the vector and scalar potentials
 Select Simulating Entangling Unitary Operator Using Non-maximally Entangled States LI Chun-Xian, WANG Cheng-Zhi, NIE Liu-Ying, LI Jiang-Fan Chin. Phys. Lett. 2009, 26 (2): 020303 .   DOI: 10.1088/0256-307X/26/2/020303 Abstract   PDF(pc) (304KB) ( 622 ) We use non-maximally entangled states (NMESs) to simulate an entangling unitary operator (EUO) with a certain probability. Given entanglement resources, the probability of the success we achieve is a decreasing function of the parameters of the EUO. Given an EUO, for certain entanglement resources the result is optimal, i.e., the probability obtains a maximal value, and for optimal result higher parameters of the EUO match more amount of entanglement resources. The probability of the success we achieve is higher than the known results under some condition.
 Select Separability of Bipartite Superoperator Based on Witness ZHANG Shun, ZHOU Zheng-Wei, GUO Guang-Can Chin. Phys. Lett. 2009, 26 (2): 020304 .   DOI: 10.1088/0256-307X/26/2/020304 Abstract   PDF(pc) (240KB) ( 608 ) Based on the isomorphic relation between operator space L(H) and Hilbert space H⊕2, Cirac et al. mapped the global superoperator to a mixed state E which has the same separability of the initial superoperator. Zhang et al. [Phys. Rev. A 76(2007)012334] provided a calculable lower bound for both the linear and nonlinear witness. We use this bound to detect the entanglement of E to judge the separability of the initial superoperator. With the help of local orthogonal observables, we directly describe the separable condition of superoperator by its each operator. Lastly, using the lower bound of the nonlinear witness, we provide a calculable entanglement factor of bipartite superoperator.
 Select Dynamical Evolution and Entanglement in a Nonlinear Interacting System SUN Hui-Ying, HUANG Xiao-Li, YI Xue Xi Chin. Phys. Lett. 2009, 26 (2): 020305 .   DOI: 10.1088/0256-307X/26/2/020305 Abstract   PDF(pc) (796KB) ( 914 ) We investigate a few features of entanglement of two types of particles coupled through a nonlinear interaction. It is shown that the entanglement created by the nonlinear interaction can reflect nonlinearity of the system. Possible observation of our prediction in a double-well trapped Bose-Einstein condensate is discussed.
 Select Continuous-Variable Quantum Teleportation of Entangled Coherent States SUN Yong, MAN Zhong-Xiao, XIA Yun-Jie Chin. Phys. Lett. 2009, 26 (2): 020306 .   DOI: 10.1088/0256-307X/26/2/020306 Abstract   PDF(pc) (366KB) ( 899 ) We propose a quantum teleportation scheme for tripartite entangled coherent state (ECS) with continuous variable. Our scheme is feasible and economical in the sense that we need only linear optical devices such as beam splitters, phase shifters and photon detectors and employ three bipartite maximally ECSs as quantum channels. We also generalize the tripartite scheme into multipartite case and calculate the minimum average fidelity for the schemes in tripartite and multipartite cases.
 Select Generation of the W State through the Cavity-Electron Interaction TANG Li Chin. Phys. Lett. 2009, 26 (2): 020307 .   DOI: 10.1088/0256-307X/26/2/020307 Abstract   PDF(pc) (183KB) ( 732 ) We present a scheme to generate the W state through the cavity-electron interaction involving a single-mode cavity and N identical electrons. Successive no-photon detection of the cavity projects the electrons to the desired W state. The time evolution of the electron-cavity system involving cavity decay is also discussed.
 Select Vibrational Spectroscopy of CH/CD Stretches in Propadiene: An Algebraic Approach Joydeep Choudhury, Nirmal Kumar Sarkar, Srinivasa Rao Karumuri, Ramendu Bhattacharjee Chin. Phys. Lett. 2009, 26 (2): 020308 .   DOI: 10.1088/0256-307X/26/2/020308 Abstract   PDF(pc) (163KB) ( 751 ) Using Hamiltonian based on Lie algebraic method, the stretching vibrational modes of C3H4 and C3D4 molecules are calculated up to higher overtones. The model appears to describe C-H and C-D stretching modes with less number of parameters. The locality parameter ξ confirms the highly local behaviour of the stretching modes of these molecules.
 Select Thermal Entanglement in the Anisotropic Heisenberg XYZ Model with Different Dzyaloshinskii-Moriya Couplings LI Da-Chuang, CAO Zhuo-Liang Chin. Phys. Lett. 2009, 26 (2): 020309 .   DOI: 10.1088/0256-307X/26/2/020309 Abstract   PDF(pc) (234KB) ( 792 ) Thermal entanglement is investigated in a two-qubit Heisenberg XYZ system with different Dzyaloshinskii-Moriya (DM) couplings. It is shown that different DM interaction parameters have different influences on the entanglement and the critical temperature. In addition, according to the relation between the real coupling coefficients Jx and Jz, a more efficient DM control parameter can be obtained by adjusting the direction of DM interaction.
 Select Realization of Three-Qubit Controlled-Phase Gate Operation with Atoms in Cavity QED System TANG Shi-Qing, ZHANG Deng-Yu, XIE Li-Jun, ZHAN Xiao-Gui, GAO Feng Chin. Phys. Lett. 2009, 26 (2): 020310 .   DOI: 10.1088/0256-307X/26/2/020310 Abstract   PDF(pc) (317KB) ( 813 ) We propose a scheme for realization of three-qubit controlled-phase gate via passing two three-level atoms through a high-Q optical cavity in a cavity QED system. In the presented protocol, the two stable ground states of the atoms act as the two controlling qubits and the zero- and one-photon Fock states of the cavity-field form the target qubit, and no auxiliary state or any measurement is required. The numerical simulation shows that the gate fidelities remain at a high level under the influence of the atomic spontaneous emission, the decay of the cavity mode and deviation of the coupling strength. The experimental feasibility of our proposal is also discussed.
 Select Simple Linear Optical Binary Measurement Tree' for Single Photonic Polarization Qubit HAN Yang, WU Wei, WU Chun-Wang, CHEN Ping-Xing, LI Cheng-Zu Chin. Phys. Lett. 2009, 26 (2): 020311 .   DOI: 10.1088/0256-307X/26/2/020311 Abstract   PDF(pc) (258KB) ( 516 ) Positive-operator-value-measurement (POVM) is one of the essential components of quantum information processing (QIP). Recently a binary measurement tree' (BST) strategy (PRA 77, 052104) is suggested for implementing arbitrary POVM by sequential two-operator POVMs. We present a simple novel two-operator POVM module via linear optics, which is employed as block to construct a binary measurement tree' for implementing arbitrary POVM on single photonic polarization qubit. The total complexity of the experimental setup is significantly reduced in contrast to the previous works. As an example, we give the detailed settings of a well-known POVM.
 Select High Efficiency of Two Efficient QSDC with Authentication Is at the Cost of Their Security QIN Su-Juan, WEN Qiao-Yan, MENG Luo-Ming, ZHU Fu-Chen Chin. Phys. Lett. 2009, 26 (2): 020312 .   DOI: 10.1088/0256-307X/26/2/020312 Abstract   PDF(pc) (236KB) ( 628 ) Two efficient protocols of quantum secure direct communication with authentication [Chin. Phys. Lett. 25(2008) 2354] were recently proposed by Liu et al. to improve the efficiency of two protocols presented in [Phys. Rev. A 75(2007)026301] by four Pauli operations. We show that the high efficiency of the two protocols is at the expense of their security. The authenticator Trent can reach half the secret by a particular attack strategy in the first protocol. In the second protocol, not only Trent but also an eavesdropper outside can elicit half-information about the secret from the public declaration.
 Select Effects of Intrinsic Decoherence on Information Transport in a Spin Chain ZENG Tian-Hai, SHAO Bin, ZOU Jian Chin. Phys. Lett. 2009, 26 (2): 020313 .   DOI: 10.1088/0256-307X/26/2/020313 Abstract   PDF(pc) (609KB) ( 709 ) Considering Milburn's intrinsic decoherence effect on quantum communication through a spin chain, we show that the~transfer~quality for~quantum state and entanglement will obviously decrease with the increasing intrinsic decoherence rate. Some odd chains are much higher than even ones for the state transfer efficiency. The state transfer of a long chain is very sensitive to the intrinsic decoherence, which turns out to be an obstacle for information transport.
 Select Flocking of Multi-agent Systems Following Virtual Leader with Time-Varying Velocity YANG Ji-Chen, LU Qi-Shao Chin. Phys. Lett. 2009, 26 (2): 020501 .   DOI: 10.1088/0256-307X/26/2/020501 Abstract   PDF(pc) (648KB) ( 1532 ) We consider the collective dynamics for a multi-agent system with a virtual leader. The velocity of the leader is time-varying and the interconnection topology of position network is switching based on the distances between agents. To track the leader in flocking, a neighbour-based local piecewise smooth controller is proposed for each agent. Using the control method, all agent velocities asymptotically approach the desired velocity while collisions can be avoided between agents. Some simulation results are provided to demonstrate the theoretical results.
 Select Ultrafast Electron Diffraction with Spatiotemporal Resolution of Atomic Motion LIANG Wen-Xi, ZHU Peng-Fei, WANG Xuan, NIE Shou-Hua, ZHANG Zhong-Chao, Clinite Rick, CAO Jian-Ming, SHENG Zheng-Ming, ZHANG Jie, Chin. Phys. Lett. 2009, 26 (2): 020701 .   DOI: 10.1088/0256-307X/26/2/020701 Abstract   PDF(pc) (412KB) ( 788 ) Ultrafast electron diffraction (UED) is a rapidly advancing technique capable of recording the atomic-detail structural dynamics in real time. We report the establishment of the first UED system in China. Employing this UED apparatus, both the coherent and the concurrent thermal lattice motions in an aluminium thin-film, trigged by ultrafast laser heating, have been observed. These results demonstrate its ability to directly measure a sub-milli-angstrom lattice spacing change on a sub-picosecond time scale.
THE PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
 Select Ds(0±) Meson Spectroscopy in Gaussian Sum Rules WEN Shui-Guo, LIU Jue-Ping Chin. Phys. Lett. 2009, 26 (2): 021201 .   DOI: 10.1088/0256-307X/26/2/021201 Abstract   PDF(pc) (346KB) ( 410 ) Masses of the Ds(0±)mesons are investigated from a view-point of ordinary light-heavy system in the framework of the Gaussian sum rules, which are worked out by means of the Laplacian transformation to the usual Borel sum rules. Using the standard input of QCD non-perturbative parameters, the corresponding mass spectra and couplings of the currents to the Ds(0±) mesons are obtained. Our results are mDs(0-)=1.968±0.016±0.003GeV and mDs(0+)=2.320±0.014±0.003GeV, which are in good accordance with the experimental data, 1.969GeV and 2.317GeV.
 Select B-Meson Wavefunction by a Comparative Analysis of the B→π,K Transition Form Factors ZENG Dai-Min, WU Xing-Gang, FANG Zhen-Yun Chin. Phys. Lett. 2009, 26 (2): 021401 .   DOI: 10.1088/0256-307X/26/2/021401 Abstract   PDF(pc) (271KB) ( 526 ) Properties of the B-meson light-cone wavefunction up to next-to-leading order Fock state expansion are studied by a comparative study of the B→π,K form factors within the kT factorization approach and the light-cone sum rule analysis. The form factors FB→π+,0,T and FB→K+,0,T are carefully re-calculated up to O(1/mb2) within the kT factorization approach in the large recoil region. The QCD light-cone sum rule is applicable in the large and intermediate energy regions, and the QCD light-cone sum rule results in Ref.[12] are adopted for such a comparative study. It is found that when the two phenomenological parameters Λ∈ [0.50,0.55]$and δ∈[0.25,0.30]$, the results of FB→π+,0,T(Q2) and FB→K+,0,T(Q2) from these two approaches are consistent with each other in the large recoil energy region.
NUCLEAR PHYSICS
 Select Isoscalar Giant Monopole Resonance in Relativistic Continuum Random Phase Approximation YANG Ding, CAO Li-Gang, MA Zhong-Yu, Chin. Phys. Lett. 2009, 26 (2): 022101 .   DOI: 10.1088/0256-307X/26/2/022101 Abstract   PDF(pc) (268KB) ( 569 ) The isoscalar giant monopole resonance (ISGMR) in nuclei is studied in the framework of a fully consistent relativistic continuum random phase approximation (RCRPA). In this method the contribution of the continuum spectrum to nuclear excitations is treated exactly by the single particle Green's function technique. The negative energy states in the Dirac sea are also included in the single particle Green's function in the no-sea approximation. The single particle Green's function is calculated numerically by a proper product of the regular and irregular solutions of the Dirac equation. The strength distributions in the RCRPA calculations, the inverse energy-weighted sum rule m-1 and the centroid energy of the ISGMR in 120Sn and 208Pb are analysed. Numerical results of the RCRPA are checked with the constrained relativistic mean field model and relativistic random phase approximation with a discretized spectrum in the continuum. Good agreement between them is achieved
 Select Differential Directed Flow of K+ Meson within Covariant Kaon Dynamics XING Yong-Zhong, ZHENG Yu-Ming, SRISAWAD Pornrad, YAN Yu-Peng, KOBDAJ Chinorat Chin. Phys. Lett. 2009, 26 (2): 022501 .   DOI: 10.1088/0256-307X/26/2/022501 Abstract   PDF(pc) (294KB) ( 583 ) The collective flow of positive charged kaons in heavy ion reactions at SIS energy is investigated within the frame of covariant kaon dynamics. The theoretical results calculated by using quantum molecular dynamics show that the rapidity distribution of K+ mesons is more sensitive to the nuclear equation of state than the differential directed flow. The contribution of various K+ production reaction channels to the rapidity distribution of the K+ is also analysed in detail. The results indicate that the rapidity distribution ofK+ mesons is mainly from the contribution of the N-Δ and N-N channel. This means that the delta resonance state plays a predominantly important role for the K+ subthreshold production..
 Select Eccentricity Scaling of Elliptic Flow in Relativistic Au+Au Collisions FENG Qi-Chun, WU Feng-Juan, ZHANG Jing-Bo, LIU Jian-Li, HUO Lei Chin. Phys. Lett. 2009, 26 (2): 022502 .   DOI: 10.1088/0256-307X/26/2/022502 Abstract   PDF(pc) (313KB) ( 396 ) Elliptic flow for Au+Au non-central collisions at √sNN=200GeV is investigated within a (2+1)-dimensional hydrodynamic model. The results show that the eccentricity scaling for the collisions is almost perfect. The evolution including the phase transition conforms to the demand of scaling invariance of hydrodynamics of the collision system.
 Select Optical Potential Parameters for Halo Nucleus System 6He+12C from Transfer Reaction 11B(7Li, 6He)12C WU Zhen-Dong, LIN Cheng-Jian, ZHANG Huan-Qiao, LIU Zu-Hua, YANG Feng, AN Guang-Peng, ZHANG Chun-Lei, ZHANG Gao-Long, JIA Hui-Ming, XU Xin-Xing, BAI Chun-Lin, YU Ning, JIA Fei Chin. Phys. Lett. 2009, 26 (2): 022503 .   DOI: 10.1088/0256-307X/26/2/022503 Abstract   PDF(pc) (449KB) ( 796 ) The optical potential parameters for the halo nucleus system 6He+12C are extracted from fits to the measured angular distributions of 11B(7Li, 6He)12C reaction at energies of 18.3 and 28.3MeV with distorted-wave Born approximation analysis. The characters of the obtained optical potential parameters are basically consistent with the results extracted from the fits to the elastic-scattering angular distributions in the literature.
 Select Effects of δ Meson on Thermal Protoneutron Star Matter YU Zi, LIU Guang-Zhou, ZHU Ming-Feng, XU Yan, ZHAO En-Guang Chin. Phys. Lett. 2009, 26 (2): 022601 .   DOI: 10.1088/0256-307X/26/2/022601 Abstract   PDF(pc) (387KB) ( 483 ) In the framework of the relativistic mean field theory, the effects of the δ meson on protoneutron star matter with hyperons at finite temperature are investigated. In thermal protoneutron star matter, the δ field potential increases with density first and then decreases. Fixing the density, the increase of the temperature suppresses the δ field potential. With the inclusion of the δ meson, the threshold densities for hyperons become lower and the abundance of trapped neutrinos decreases. The most important effect of the δ meson is to increase the abundance of hyperons in the inner core range of protoneutron stars. With the rise of the temperature, the density range where the δ meson plays an important role is narrowed and the effects of the δ meson are suppressed. Moreover, the protoneutron star mass and radius are nearly not affected by the δ meson
 Select Longitudinal Single Bunch Instability Caused by Wake Field of Electron Cloud LIU Yu-Dong, YU Cheng-Hui Chin. Phys. Lett. 2009, 26 (2): 022901 .   DOI: 10.1088/0256-307X/26/2/022901 Abstract   PDF(pc) (355KB) ( 436 ) The electron cloud accumulated in the vicinity of positron beam generates longitudinal electric field during the passage of bunch. The longitudinal interaction between bunch and electron cloud can lead to the distortion of the bunch shape. We use a simple analytic formula to calculate the longitudinal electric field due to electron cloud. Based on the longitudinal wake field, the macro-particle tracking method is used to simulate the variation of bunch longitudinal profile in different electron cloud densities and the simulation also shows that the synchrotron oscillation tune is slightly shifted by the wake field. By comparing the simulation results and the analytical estimation from potential distortion theory, the longitudinal wake field from electron cloud can be seen as a potential well effect.
ATOMIC AND MOLECULAR PHYSICS
 Select Realization of High Optical Density Rb Magneto-optical Trap HAN Yan-Xu, LIU Yong-Hong, ZHANG Chun-Hong, LI Shu-Jing, WANG Hai Chin. Phys. Lett. 2009, 26 (2): 023201 .   DOI: 10.1088/0256-307X/26/2/023201 Abstract   PDF(pc) (479KB) ( 1798 ) We report experimental demonstration of a magneto-optical trap (MOT) of Rb atoms with a high optical density. With 2.2-cm-diameter cooling laser beams, we achieve an optical density of nearly 11 for about 2.6×1010 trapped Rb atoms with the beam intensity of about 6.6mW/cm2 per beam. The temperature of the cold atoms is about 250μK. Furthermore, by ramping the magnetic field gradient from 8G/cm to about 20G/cm, the atomic cloud in the MOT is compressed and the optical density is up to 16.
 Select Low Energy Scattering of Electrons by Sodium JIAO Li-Guang, ZHOU Ya-Jun, YU Rong-Mei Chin. Phys. Lett. 2009, 26 (2): 023401 .   DOI: 10.1088/0256-307X/26/2/023401 Abstract   PDF(pc) (323KB) ( 614 ) The low energy scattering of electrons by sodium at incident energies up to ionization threshold are calculated by applying the momentum space coupled-channel-optical (CCO) method. The present results are in good agreement with the previous experimental and theoretical results. Furthermore, three resonances in the total cross sections observed by previous experiments are proved by the present calculation.
 Select Differential Cross Sections for High-Lying Vibrational Excitations (ν=0→ν'=1,2,...,9,10 ) of e-H2 Scattering ZENG Yang-Yang, FENG Hao, SUN Wei-Guo, WANG Bin Chin. Phys. Lett. 2009, 26 (2): 023402 .   DOI: 10.1088/0256-307X/26/2/023402 Abstract   PDF(pc) (508KB) ( 709 ) A theoretical investigation on the differential cross section (DCS) from low-energy electron scattering of high-lying vibrational excited H2 molecules is reported. The body-frame vibrational close-coupling (BFVCC) approach is used to solve the scattering equations. Quantum scattering potentials include static, exchange, and polarization contributions based on ab initio calculations. By including the contributions of 9 partial waves (Ne=9), 18 Morse vibrational states (Nυ=18), and 16 molecular symmetries (Λ=0,1,...,7), the calculated DCSs have good agreement with available experimental measurements and theoretical studies, and show that high angular momenta and good vibrational wavefunctions are necessary to better describe the scattering physics of electron-molecule vibrational excitation collisions.
 Select Charge and Energy Dependences of Ionization and Transfer for Helium in Collisions with Fast Charged Projectiles FU Hong-Bin, WANG Bao-Hong, DING Bao-Wei, LIU Zhao-Yuan Chin. Phys. Lett. 2009, 26 (2): 023403 .   DOI: 10.1088/0256-307X/26/2/023403 Abstract   PDF(pc) (371KB) ( 656 ) The classical method within the independent electron model is employed to investigate (i) charge dependences of single and double ionization for helium by various charged ions Aq+ (q=1-8) at impact energies of 0.64 and 1.44MeV/u, respectively, (ii) energy dependences of transfer ionization for helium by 0.5-3MeV/u A8,9+ ions impact. The Lenz-Jensen model of the atom is applied instead of the Bohr model of the atom, and the impact-parameter dependences are also introduced into the calculations. Satisfactory agreement is found between theoretical and experimental data.
 Select Evolution of Quantum Phase Space Distribution: a Trajectory-Density Approach ZHANG Xue-Feng, ZHENG Yu-Jun Chin. Phys. Lett. 2009, 26 (2): 023404 .   DOI: 10.1088/0256-307X/26/2/023404 Abstract   PDF(pc) (226KB) ( 579 ) The trajectory-density method of a quantum system is developed by using local Koopman and Frobenius-Perron operators. We propose a new scheme of approximation from two sets of trajectory-density mixed equations. By examining the local generation and termination of trajectories, we show how they can be adopted to the propagation of negative values of the Wigner function even if it starts off positive everywhere.
FUNDAMENTAL AREAS OF PHENOMENOLOGY(INCLUDING APPLICATIONS)
 Select Nonlinear Photoluminescence from ZnO Nanobelts ZHOU Zhang-Kai, HAO Zhong-Hua, MEI Zong-Wei, WEN Xiao-Gang, YANG Shi-He Chin. Phys. Lett. 2009, 26 (2): 024201 .   DOI: 10.1088/0256-307X/26/2/024201 Abstract   PDF(pc) (564KB) ( 595 ) The nonlinear photoluminescence (PL) including second-harmonic generation (SHG) and the multiphoton luminescence (MPL) around 385nm and 530nm from ZnO nanobelts are investigated by using near-infrared excitations. The excitation wavelength dependence of MPL intensity reveals resonant energy transfer from SHG to MPL near the band gap excitation. The lifetime measurement of the MPL shows a much slower decay process of the defect emission, which results from the generation and recombination of both donors and acceptors on the disordered surface of the ZnO nanobelts.
 Select A Novel Three-Dimensional Wide-Angle Beam Propagation Method Based on Split-Step Fast Fourier Transform ZANG Wei-Ping, CHENG Hua, TIAN Jian-Guo Chin. Phys. Lett. 2009, 26 (2): 024202 .   DOI: 10.1088/0256-307X/26/2/024202 Abstract   PDF(pc) (294KB) ( 908 ) A novel three-dimensional wide-angle beam propagation method based on the split-step fast Fourier transform is developed. The formulation is based on the three-dimensional Helmholtz wave equation. Each propagation step is performed by utilizing both the FFT and split-step scheme. The solution of Helmholtz wave equation does not make the slowly varying envelope and one-way propagation approximations. To validate the efficiency and accuracy, numerical results for a propagation beam in a tilted step-index optical waveguide are compared with other beam propagation algorithms.
 Select Reversible Resistance Switching Effect in Amorphous Ge1Sb4Te7 Thin Films without Phase Transformation SUN Hua-Jun, HOU Li-Song, WU Yi-Qun, TANG Xiao-Dong Chin. Phys. Lett. 2009, 26 (2): 024203 .   DOI: 10.1088/0256-307X/26/2/024203 Abstract   PDF(pc) (300KB) ( 556 ) We demonstrate a reversible resistance switching effect that does not rely on amorphous-crystalline phase transformation in a nanoscale capacitor-like cell using Ge1Sb4Te7 films as the working material. The polarity and amplitude of the applied electric voltage switches the cell resistance between low- and high-resistance states, as revealed in the current-voltage characteristics of the film by conductive atomic force microscopy (CAFM). This reversible SET/RESET switching effect is induced by voltage pulses and their polarity. The change of electrical resistance due to the switching effect is approximately two orders of magnitude.
 Select Research of Plasma Characteristics of the Radio-Frequency Discharge in O2 and Its Mixtures ZHANG Xue-Ling, WANG Xin-Bing, LI Guo-Fu Chin. Phys. Lett. 2009, 26 (2): 024204 .   DOI: 10.1088/0256-307X/26/2/024204 Abstract   PDF(pc) (458KB) ( 625 ) Electron mean energy and the effects of gas mixture are studied theoretically and experimentally. The electron mean energy in O2 and its mixtures is obtained by solving Boltzmann's equation. The experiments of the Langmuir probe system and spectral analysis are carried out. It is shown that electron temperature goes down with the increasing pressure, narrowing pulse width and the addition of helium and argon. According to the intensity of oxygen atom at 777.19nm, xenon is more effective in inhibition of O2 decomposition than helium and argon.
 Select Formation of Hot Images in Laser Beams through a Self-defocusing Kerr Medium Slab WANG You-Wen, DENG Jian-Qin, CHEN Lie-Zun, WEN Shuang-Chun, YOU Kai-Ming, Chin. Phys. Lett. 2009, 26 (2): 024205 .   DOI: 10.1088/0256-307X/26/2/024205 Abstract   PDF(pc) (510KB) ( 461 ) A nonlinear hot image is usually thought as of a special case of self-focusing, and thus occurs when a laser beam propagates through a slab of self-focusing medium. Here we show theoretically that a hot image may also be formed by a thin slab of self-defocusing medium. The physical origin for this hot image formation is akin to the in-line volume--phase holographic imaging due to the intensity-dependent refractive-index modulation of the self-defocusing medium. Numerical simulations confirm the theoretical prediction and further identify the dependence of the hot image on the beam power, the modulation depth of obscuration and the thickness of self-defocusing medium. The analysis presented here brings new insight into the physics of hot image formation in the high power laser system
 Select High Cost Performance Organic-Inorganic Hybrid Material for Electro-optic Devices SUN Jie, ZHU Gui-Hua, SUN Xiao-Qiang, LI Tong, GAO Wei-Nan, ZHANG Da-Ming, HOU A-Lin Chin. Phys. Lett. 2009, 26 (2): 024206 .   DOI: 10.1088/0256-307X/26/2/024206 Abstract   PDF(pc) (428KB) ( 475 ) We report a low-cost electro-optic (EO) sol-gel material with large EO coefficient and excellent poling stability for EO devices. Disperse red 1 (DR1) chromophore is doped in the three-dimensional silicon dioxide/titanium dioxide network possessing a high γ33 (88pm/V at 1300nm wavelength and 71pm/V at 1550nm wavelength). Favourable poled stability (less than 5% relaxed after 2500 hours at 80°C) and low absorption are demonstrated. Strip-loaded waveguide Mach-Zehnder (M-Z) modulators are implemented based on this synthesized EO material, showing 7V half-wave voltage and less than 9dB insertion loss at 1550nm wavelength..
 Select Polarization Changes of Partially Coherent Electromagnetic Vortex Beams Propagating in Turbulent Atmosphere SHU Jian-Hua, CHEN Zi-Yang, PU Ji-Xiong Chin. Phys. Lett. 2009, 26 (2): 024207 .   DOI: 10.1088/0256-307X/26/2/024207 Abstract   PDF(pc) (371KB) ( 834 ) We investigate the polarization change of partially coherent electromagnetic vortex beams propagating in turbulent atmosphere. It is shown that the polarization of the beams will experience changes, and the changes of the polarization are dependent on the spatial coherence, topological charges of the beams, and the degree of polarization of the source plane and the atmospheric turbulence. The results obtained may have applications in space optical communication.
 Select Photoluminescence from Nd Doped Anodic Aluminium Oxide ZHOU Zhang-Kai, PENG Xiao-Niu, SU Xiong-Rui, HAO Zhong-Hua, Chin. Phys. Lett. 2009, 26 (2): 024208 .   DOI: 10.1088/0256-307X/26/2/024208 Abstract   PDF(pc) (406KB) ( 692 ) We prepare Nd doped anodic aluminium oxide (Nd:AAO) template by using Nd doped aluminium foils through two-step anodization processes. Photoluminescence (PL) from the Nd:AAO template with the annealing temperature higher than 400°C is observed, and the PL intensity enhanced with the increasing annealing temperature is found. We investigate the crystallization of Nd:AAO template and the excitation wavelength dependence of PL intensity, showing that the PL results from the Nd doped in the template. The approach presented may probably facilitate the fabricating of AAO with good light-emitting property, which can be used in fabrication of multifunctional nanosized films and may find applications in photonic devices.
 Select A ZnGeP2 Optical Parametric Oscillator with Mid-IR Output Power 3W Pumped by a Tm,Ho:GdVO4 Laser YAO Bao-Quan, ZHU Guo-Li, JU You-Lun, WANG Yue-Zhu Chin. Phys. Lett. 2009, 26 (2): 024209 .   DOI: 10.1088/0256-307X/26/2/024209 Abstract   PDF(pc) (379KB) ( 735 ) We report an efficient mid-infrared optical parametric oscillator (OPO) pumped by a pulsed Tm,Ho-codoped GdVO4 laser. The 10-W Tm,Ho:GdVO4 laser pumped by a 801nm diode produces 20ns pulses with a repetition rate of 10kHz at wavelength of 2.048μm. The ZnGeP2 (ZGP) OPO produces 15-ns pulses in the spectral regions 3.65-3.8μm and 4.45-4.65μm simultaneously. More than 3W of mid-IR output power can be generated with a total OPO slope efficiency greater than 58% corresponding to incident 2μm pump power. The diode laser pump to mid-IR optical conversion efficiency is about 12%.
 Select Fabrication of Colloidal Photonic Crystals with Heterostructure by Spin-Coating Method WANG Ai-Jun, CHEN Sheng-Li, DONG Peng, CAI Xiao-Gang, ZHOU Qian, YUAN Gui-Mei, HU Chun-Tian, ZHNG Dao-Zhong Chin. Phys. Lett. 2009, 26 (2): 024210 .   DOI: 10.1088/0256-307X/26/2/024210 Abstract   PDF(pc) (505KB) ( 1081 ) Colloidal photonic crystal heterostructures, composed of two opaline photonic crystal films of silica spheres with different diameters, are fabricated by a two-step spin-coating method. Scanning electron microscopy (SEM) and UV-vis spectrophotometer are used to characterize the heterostructures. The SEM images show good ordering of the two-layer colloidal crystals constituting the heterostructures. The transmission spectra measured from the (111) plane in the heterostructure show that the composite colloidal photonic crystals have double photonic stop bands. Furthermore, when the sizes of the silica spheres used for fabricating the composite photonic crystal are slightly different, the transmission spectrum shows that the composite photonic crystals have more extended bandgap than that of the individual photonic crystals due to partial overlapping of its two photonic stop bands.
 Select Optimization of Pulse Temporal Contrast in Optical Parametric Chirped Pulse Amplification WANG Yan-Hai, PAN Xue, LI Xue-Chun, LIN Zun-Qi Chin. Phys. Lett. 2009, 26 (2): 024211 .   DOI: 10.1088/0256-307X/26/2/024211 Abstract   PDF(pc) (486KB) ( 701 ) In optical parametric chirped pulse amplification (OPCPA), the degradation of temporal contrast of the compressed signal pulse mainly results from spectral clipping in the grating stretcher with finite size of the optics, parametric fluorescence (PF) and the spectral variations transferred from temporal fluctuation of the pump pulse. The temporal contrast of the recompressed amplified pulse in the OPCPA system is studied numerically and a number of solutions are considered and optimized to achieve the highest temporal contrast.
 Select Experimental Investigation of Integrated Optical Intensive Impulse Electric Field Sensors SUN Bao, CHEN Fu-Shen Chin. Phys. Lett. 2009, 26 (2): 024212 .   DOI: 10.1088/0256-307X/26/2/024212 Abstract   PDF(pc) (373KB) ( 641 ) We design and fabricate an integrated optical electric field sensor with segmented electrode for intensive impulse electric field measurement. The integrated optical sensor is based on a Mach-Zehnder interferometer with segmented electrodes. The output/input character of the sensing system is analysed and measured. The maximal detectable electric field range (-75kV/m to 245kV/m) is obtained by analysing the results. As a result, the integrated optics electric field sensing system is suitable for transient intensive electric field measurement investigation.
 Select Analytical Model of Doppler Spectra of Light Backscattered from Rotating Convex Bodies of Revolution in the Global Cartesian Coordinate System GONG Yan-Jun, WU Zhen-Sen, WU Jia-Ji Chin. Phys. Lett. 2009, 26 (2): 024213 .   DOI: 10.1088/0256-307X/26/2/024213 Abstract   PDF(pc) (385KB) ( 453 ) We present an analytical model of Doppler spectra in backscattering from arbitrary rough convex bodies of revolution rotating around their axes in the global Cartesian coordinate system. This analytical model is applied to analyse Doppler spectra in backscatter from two cones and two cylinders, aswell as two ellipsoids of revolution. We numerically analyse the influences of attitude and geometry size of objects on Doppler spectra. The analytical model can give contribution of the surface roughness, attitude and geometry size of convex bodies of revolution to Doppler spectra and may contribute to laser Doppler velocimetry as well as ladar applications.
 Select Low-Power Super-resolution Readout with Antimony Bismuth Alloy Film as Mask layer JIANG Lai-Xin, WU Yi-Qun, WANG Yang, WEI Jing-Song, GAN Fu-Xi Chin. Phys. Lett. 2009, 26 (2): 024214 .   DOI: 10.1088/0256-307X/26/2/024214 Abstract   PDF(pc) (411KB) ( 437 ) Sb-Bi alloy films are proposed as a new kind of super-resolution mask layer with low readout threshold power. Using the Sb-Bi alloy film as a mask layer and SiN as a protective layer in a read-only memory disc, the super-resolution pits with diameters of 380nm are read out by a dynamic setup, the laser wavelength is 780nm and the numerical aperture of pickup lens is 0.45. The effects of the Sb-Bi thin film thickness, laser readout power and disc rotating velocity on the readout signal are investigated. The results show that the threshold laser power of super-resolution readout of the Sb-Bi mask layer is about 0.5mW, and the corresponding carrier-to-noise ratio is about 20dB at the film thickness of 50nm. The super-resolution mechanism of the Sb-Bi alloy mask layer is discussed based on its temperature dependence of reflection.
 Select Phase Transition in Acoustic Localization in a Soft Medium Permeated with Air Bubbles LIANG Bin, ZOU Xin-Ye, CHENG Jian-Chun Chin. Phys. Lett. 2009, 26 (2): 024301 .   DOI: 10.1088/0256-307X/26/2/024301 Abstract   PDF(pc) (289KB) ( 435 ) Propagation of an acoustic wave in a soft medium permeated with air bubbles is theoretically investigated by using a self-consistent approach. The soft medium is assumed to be viscoelastic to estimate the effect of acoustic absorption on the acoustic localization in such a medium. The oscillation phases of bubbles are examined by employing a phase diagram method. A collective oscillation of the bubbles is observed once the acoustic localization occurs, which is known as a phenomenon of phase transition', and such a phenomenon persists as we manually increase the viscosity factor of the soft medium. Therefore it is proven that the phenomenon of phase transition may serve as a unique criterion to effectively identify acoustic localization in a bubbly soft medium even in the presence of viscosity, and the directions of the phase vectors help to determine the extent of localization. This is of practical significance for experimental research studying the acoustic localization in such a medium, for which the presence of viscosity generally causes great ambiguity in distinguishing the effects of localization and acoustic absorption.
 Select Shear Profiles and Velocity Distribution in Dense Shear Granular Flow WANG Deng-Ming, ZHOU You-He Chin. Phys. Lett. 2009, 26 (2): 024501 .   DOI: 10.1088/0256-307X/26/2/024501 Abstract   PDF(pc) (410KB) ( 587 ) We perform DEM simulations to investigate the influence of the packing fraction γ on the shape of mean tangential velocity profile in a 2D annular dense shear granular flow. There is a critical packing fraction γc. For γ<γc, the mean tangential velocity profile shows a roughly exponential decay from the shearing boundary and is almost invariant to the imposed shear rate. However, for γ>γc, the tangential velocity profile exhibits a rate-dependence feature and changes from linear to nonlinear gradually with the increasing shear rate. Furthermore, the distributions of normalized tangential velocities at differentpositions along radial direction exhibit the Gaussian or the composite Gaussian distributing features.
 Select Three-Dimensional Waves in Tilt Thermal Boundary Layers TAO Jian-Jun, YUAN Xiang-Jiang Chin. Phys. Lett. 2009, 26 (2): 024701 .   DOI: 10.1088/0256-307X/26/2/024701 Abstract   PDF(pc) (287KB) ( 497 ) We numerically and theoretically study the stabilities of tilt thermal boundary layers immersed in stratified air. An interesting phenomenon is revealed: the stationary longitudinal-roll mode becomes unstable to some oscillating state even when the Grashof number is smaller than its corresponding critical value. By stability analysis, this phenomenon is explained in terms of a new three-dimensional wave mode. The effect of the tilt angle on the stability of the boundary flows is investigated. Since the new three-dimensional wave is found to be the most unstable mode when the title angle is between 30° and 64°, it is expected to play an important role in the transition to turbulence.
 Select Pattern Formation in the Turing-Hopf Codimension-2 Phase Space in a Reaction-Diffusion System YUAN Xu-Jin, SHAO Xin, LIAO Hui-Min, OUYANG Qi Chin. Phys. Lett. 2009, 26 (2): 024702 .   DOI: 10.1088/0256-307X/26/2/024702 Abstract   PDF(pc) (648KB) ( 661 ) We systematically investigate the behaviour of pattern formation in a reaction-diffusion system when the system is located near the Turing-Hopf codimension-2 point in phase space. The chloride-iodide-malonic acid (CIMA) reaction is used in this study. A phase diagram is obtained using the concentration of polyvinyl alcohol (PVA) and malonic acid (MA) as control parameters. It is found that the Turing-Hopf mixed state appears only in a small vicinity near the codimension-2 point, and has the form of hexagonal pattern overlapped with anti-target wave; the boundary line separating the Turing state and the wave state is independent of the concentration of MA, only relies on the concentration of PVA. The corresponding numerical simulation using the Lengyel-Epstein (LE) model gives a similar phase diagram as the experiment; it reproduces most patterns observed in the experiment. However, the mixed state we obtain in simulation only appears in the anti-wave tip area, implying that the 3-D effect in the experiments may change the pattern forming behaviour in the codimension-2 regime.
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
 Select Whistler-Mode Waves Growth by a Generalized Relativistic Kappa-Type Distribution ZHOU Qing-Hua, JIANG Bin, SHI Xiang-Hua, LI Jun-Qiu Chin. Phys. Lett. 2009, 26 (2): 025201 .   DOI: 10.1088/0256-307X/26/2/025201 Abstract   PDF(pc) (314KB) ( 500 ) The instability of field-aligned Whistler-mode waves in space plasmas is studied by using a recently developed generalized relativistic kappa-type (KT) distribution. Numerical calculations are performed for a direct comparison between the new KT distribution and the current kappa distribution. We show that the wave growth for the KT distribution tends to occur in the lower wave frequency (e.g., ω≤0.1 Ωe) due to a larger fractional number of the resonant electrons ηrel (which controls the wave growth), while primarily locating in the higher wave frequency for the kappa distribution. Moreover, the relativistic anisotropy Arel by the KT distribution is found to be smaller than that by the kappa distribution, leading to a smaller peak of wave growth. The results present a further understanding of plasma wave instability particularly in those plasmas where relativistic electrons are present.
 Select Design of a TE10-TE30 Rectangular Mode Converter for 4.6GHz LHCD Launcher in the Experimental Advanced Superconducting Tokamak WANG Xiao-Jie, LIU Fu-Kun, ZHAO Lian-Min, JIA Hua, LIU Hong-Bao, KUANGGuang-Li Chin. Phys. Lett. 2009, 26 (2): 025202 .   DOI: 10.1088/0256-307X/26/2/025202 Abstract   PDF(pc) (327KB) ( 1569 ) A compact rectangular TE10-TE30 mode converter is developed for the lower hybrid current drive (LHCD) launcher on the Experimental Advanced Superconducting Tokamak (EAST) at 4.6GHz. The converter with periodic width perturbation aims to divide the microwave power into three sub-waveguides in the poloidal direction. We present the design and numerical calculation of the mode converter. Calculations are performed on the ripple wall converter by codes based on numerical solving the coupled-mode differential equations and on the simulation of the High Frequency Structure Simulator (HFSS) package. The resulting conversion efficiency from TE10 mode to TE30 mode exceeds 95% within the bandwidth from 4.56GHz to 4.64GHz, and the return loss of the oversized transducer can be considerably decreased to 0.068% by means of a capacitive button embedded in the E-plane of the waveguide.
CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES
 Select Structure Characterization of Modified Polyimide Films Irradiated by 2MeV Si Ions CHEN Tian-Xiang, YAO Shu-De, WANG Kun, WANG Huan, DING Zhi-Bo, CHENDi Chin. Phys. Lett. 2009, 26 (2): 026101 .   DOI: 10.1088/0256-307X/26/2/026101 Abstract   PDF(pc) (394KB) ( 730 ) Structures of polyimide (6051) films modified by irradiation of 2.0MeV Si ions with different fluences are studied in detail. Variations of the functional groups in polyimide are investigated by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and Raman spectroscopy. The results indicate that the functional groups can be destroyed gradually with the increasing ion fluence. The variations of structure and element contents are characterized by x-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS) and x-ray photoelectron spectroscopy (XPS). The results indicate that the contents of N and O decrease significantly compared with the original samples, some graphite-like and carbon-rich phases are formed in the process of irradiation.
 Select Correlation between Displacement Damage Dose and Proton Irradiation Effects on GaInP/GaAs/Ge Space Solar Cells LIU Yun-Hong, WANG Rong, , CUI Xin-Yu, WANG Yong-Xia, Chin. Phys. Lett. 2009, 26 (2): 026102 .   DOI: 10.1088/0256-307X/26/2/026102 Abstract   PDF(pc) (352KB) ( 986 ) The irradiation effects of 0.28-2.80MeV protons on GaInP/GaAs/Ge solar cells have been analysed, and then correlated with the displacement damage dose. The results of I-V and spectral response measurements, combined with the SRIM-derived vacancies produced rates, show that the degradation of the solar cells is largely determined by the displacement damage of the GaAs sub-cell. Thus the SRIM-derived NIEL values for protons in the GaAs sub-cell are used to calculate the displacement damage dose. It is shown that the irradiation effects of the solar cells caused by protons at different energies are correlated well with the aid of displacement damage dose.
 Select Theoretical Strength of Face-Centred-Cubic Single Crystal Copper Based on a Continuum Model LIU Xiao-Ming, LIU Zhan-Li, YOU Xiao-Chuan, NIE Jun-Feng, ZHUANG Zhuo Chin. Phys. Lett. 2009, 26 (2): 026103 .   DOI: 10.1088/0256-307X/26/2/026103 Abstract   PDF(pc) (440KB) ( 2246 ) The constitutive relation of single crystal copper based on atomistic potential is implemented to capture the nonlinear inter-atomic interactions. Uniaxial loading tests of single crystal copper with inter-atomic potential finite-element model are carried out to determine the corresponding ideal strength using the modified Born stability criteria. Dependence of the ideal strength on the crystallographic orientation is studied, and tension-compression asymmetry in ideal strength is also investigated. The results suggest that asymmetry for yielding strength of nano-materials may result from anisotropic character of crystal instability. Moreover, the results also reveal that the critical resolved shear stress in the direction of slip is not an accurate criterion for the ideal strength since it could not capture the dependence on the loading conditions and hydrostatic stress components for the ideal strength.
 Select Growth of High-Quality Decagonal Al-Cu-Co Quasicrystals from Ternary Melt FAN Zhen-Jun, PAN Feng, ZHANG Dian-Lin Chin. Phys. Lett. 2009, 26 (2): 026104 .   DOI: 10.1088/0256-307X/26/2/026104 Abstract   PDF(pc) (281KB) ( 698 ) By changing the initial elements, we obtain high-quality samples of Al-Cu-Co decagonal quasicrystals with a wide range of composition. The sizes of the samples are typically several centimetres in length and 2-3mm in diameter. These samples are identified to be decagonal single grains by powder x-ray diffraction method, and the composition is homogeneous confirmed by EDX and chemical method.
 Select A Simple System to Measure Superconducting Transition Temperature at High Pressure YU Yong, ZHAI Guang-Jie, JIN Chang-Qing Chin. Phys. Lett. 2009, 26 (2): 026201 .   DOI: 10.1088/0256-307X/26/2/026201 Abstract   PDF(pc) (265KB) ( 491 ) A simple hydride system is fabricated to measure the superconducting transition temperature Tc under high pressure using a diamond anvil cell (DAC). The system is designed with centrosymetric coils around the diamond that makes it easy to keep balance between the pick-up coil and the inductance coil, while the superconducting states can be modulated with a low-frequency small external magnetic field. Using the device we successfully obtain the Tc evolution as a function of applied pressure up to 10GPa for YBa2Cu3O6+δ superconductor single crystal.
 Select Density-Functional Fidelity Approach to Quantum Phase Transitions GU Shi-Jian Chin. Phys. Lett. 2009, 26 (2): 026401 .   DOI: 10.1088/0256-307X/26/2/026401 Abstract   PDF(pc) (232KB) ( 782 ) We propose a new approach to quantum phase transitions in terms of the density-functional fidelity, which measures the similarity between density distributions of two ground states in parameter space. The key feature of the approach is such that the density-functional fidelity can be measured easily in experiments. Both the validity and versatility of the approach are checked by the Lipkin-Meshkov-Glick model and the one-dimensional Hubbard model.
 Select Thermal Expansion Anomaly and Spontaneous Magnetostriction of Y2Fe14Al3 Compound HAO Yan-Ming, ZHANG Yan-Yan, JIANG Xin-Yuan, GAO Chun-Jing, WU Yan-Zhao Chin. Phys. Lett. 2009, 26 (2): 026501 .   DOI: 10.1088/0256-307X/26/2/026501 Abstract   PDF(pc) (314KB) ( 438 ) The structure and magnetic properties of Y2Fe14Al3 compound are investigated by means of x-ray diffraction and magnetization measurements. The Y2Fe14Al3 compound has a hexagonal Th2Ni17-type structure. Negative thermal expansion is found in Y2Fe14Al3 compound in the temperature range from 403 to 491K by x-ray dilatometry. The coefficient of the average thermal expansion is -α=-2.54 ×10-5K-1. The spontaneous magnetostrictive deformations from 283 to 470K are calculated by means of the differences between the experimental values of the lattice parameters and the corresponding values extrapolated from the paramagnetic range. The result shows that the spontaneous volume magnetostrictive deformation ωS decreases from 5.74×10-3 to nearly zero with temperature increasing from 283 to 470K, the spontaneous linear magnetostrictive deformation λc along the c-axis is larger than the spontaneous linear magnetostrictive deformation λa in basal-plane in the same temperature below 350K.
 Select Cu(In, Ga)Se2 Thin Films on Flexible Polyimide Sheet: Structural and Electrical Properties versus Composition ZHANG Li, HE Qing, JIANG Wei-Long, LI Chang-Jian, SUN Yun Chin. Phys. Lett. 2009, 26 (2): 026801 .   DOI: 10.1088/0256-307X/26/2/026801 Abstract   PDF(pc) (381KB) ( 1251 ) The structural and electrical properties of Cu(In,Ga)Se2 (CIGS) films grown on polyimide (PI) sheet using the three-stage co-evaporation process are investigated by x-ray diffraction spectra (XRD), scanning electron microscopy (SEM), Raman spectra, and Hall effect measurements, respectively. The results show that the properties of CIGS films on PI sheet are strongly dependent on the compositional ratio of Cu/(In+Ga) (Cu/III). In contrast to the non-stoichiometric CIGS films, stoichiometric CIGS films show better structural and electrical properties, such as a relatively larger grain size, lower resistivity and higher carrier concentration. The flexible CIGS solar cells on PI sheet with the conversion efficiencies of 9.7% and 6.6% are demonstrated for the CIGS absorber layer with CuIII of 0.96 and 0.76, respectively (active area, 0.20cm2). The cell efficiency for Cu-poor CIGS films is limited by a relatively lower open circuit voltage and fill factor.
 Select Electrically Driven InAs Quantum-Dot Single-Photon Sources XIONG Yong-Hua, NIU Zhi-Chuan, DOU Xiu-Ming, SUN Bao-Quan, HUANG She-Song, NI Hai-Qiao, DU Yun, XIA Jian-Bai Chin. Phys. Lett. 2009, 26 (2): 026802 .   DOI: 10.1088/0256-307X/26/2/026802 Abstract   PDF(pc) (395KB) ( 701 ) Electrically driven single photon source based on single InAs quantum dot (QDs) is demonstrated. The device contains InAs QDs within a planar cavity formed between a bottom AlGaAs/GaAs distributed Bragg reflector (DBR) and a surface GaAs-air interface. The device is characterized by I-V curve and electroluminescence, and a single sharp exciton emission line at 966nm is observed. Hanbury Brown and Twiss (HBT) correlation measurements demonstrate single photon emission with suppression of multiphoton emission to below 45% at 80K
 Select Various Trap States at SiGe-SiO2 Interface Formed by a Pulsed Laser HUANG Wei-Qi, LÜ, Quan, XU Li, ZHANG Rong-Tao, WANG Hai-Xu, JIN Feng Chin. Phys. Lett. 2009, 26 (2): 026803 .   DOI: 10.1088/0256-307X/26/2/026803 Abstract   PDF(pc) (399KB) ( 485 ) We report fabrication of low-dimensional structures in air by a pulsed laser on SiGe alloy samples in which different oxide structures are formed by laserirradiation and annealing treatment. The micro-structures on SiGe are more complex than those on Si. A series of photoluminescence (PL) emission is observed due to various trap states at the SiGe-SiO2 interface formed under different preparing conditions. The peak centre of PL emission exhibits red-shift from Si to SiGe because of narrower gap. A model for explaining the PLemission is proposed in which the trap states of the interface between some oxide and SiGe play an important role.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
 Select Long Lifetime State of Shallow Donor Centres for Silicon Based THz Sources YU Chen-Hui, ZHANG Bo, CHEN Chang-Qing, YU Li-Bo, LU Wei, SHEN Xue-Chu Chin. Phys. Lett. 2009, 26 (2): 027101 .   DOI: 10.1088/0256-307X/26/2/027101 Abstract   PDF(pc) (336KB) ( 398 ) Impurity centres in high purity silicon with ionization energies 38.32 and 40.09meV are observed by photo-thermal ionization spectroscopy measurements. Their typical shallow donor characteristics are approved by good agreement with theoretic evaluation under varying magnetic fields. The 2p0 state lifetime of one donor centres are more than 3 times longer than that of phosphorus in the same silicon sample. Compared to phosphorus which has been already successfully exploited to produce silicon-based THz radiations, this shallow donor centre has a pronounced enhancement on lifetime and quality factor of population inversion level. Hence, silicon with this donor centre would be a potential excellent candidate to develop improved silicon-based THz sources.
 Select Influence of Oxygen Vacancy on Transport Property in Perovskite Oxide Heterostructures HAN Peng, JIN Kui-Juan, LÜ, Hui-Bin, JIA Jin-Feng, QIU Jie, HU Chun-Lian, YANG Guo-Zhen Chin. Phys. Lett. 2009, 26 (2): 027301 .   DOI: 10.1088/0256-307X/26/2/027301 Abstract   PDF(pc) (445KB) ( 633 ) Effect of oxygen vacancy on transport property of perovskite microstructures is studied theoretically. Compared with calculated and measured I-V curves, it is revealed that electron conduction plays an important role in the oxygen nonstoichiometry perovskite heterostructures even with hole-doped or un-doped material due to the oxygen vacancies. In addition, a detailed understanding of the influence of oxygen vacancy concentration and temperature on the conduction characteristics of oxide heterojunction with both forward and reverse biases is obtained by calculation.
 Select Schottky Barrier Formation at a Carbon Nanotube-Scandium Junction HE Yu, ZHANG Ming, ZHANG Jin-Yu, WANG Yan, YU Zhi-Ping Chin. Phys. Lett. 2009, 26 (2): 027302 .   DOI: 10.1088/0256-307X/26/2/027302 Abstract   PDF(pc) (348KB) ( 450 ) Recent experiment shows that scandium (Sc) can make a good performance contact with carbon nanotubes (CNTs) to fabricate n-type field effect transistor (n-FET). We study the Schottky barrier (SB) of scandium (Sc) and palladium (Pd) with a (8,0) single-wall CNT (SWCNT) using first-principles calculation. It is found that the p-type SB height (SBH) of the Pd--CNT contact is about 0.34eV, which is in good agreement with the experimental data. For the Sc-CNT contact, an n-type contact is formed and the SBH is about 0.08eV in agreement with the experimental observations. Our calculation demonstrates that by contacting CNT with Pd and Sc, p-FET and n-FET can be fabricated, respectively. The dipole effect at the interface is used to explain our result
 Select Dominance of Antinodal Quasiparticles on the Transport Properties of Heavily Overdoped High-Tc Cuprates: Infrared-Reflectance Spectra MA Yong-Chang, ZHAO Jie, AN Yu-Kai, LIU Ji-Wen Chin. Phys. Lett. 2009, 26 (2): 027401 .   DOI: 10.1088/0256-307X/26/2/027401 Abstract   PDF(pc) (470KB) ( 419 ) The infrared reflectance spectrum up to 2500cm-1 for heavily overdoped Tl-2201 at 300K has been analysed under the semiclassical approximation. In this approach, we use two independent sets of parameters to fit the reflectance: the momentum-dependent Fermi velocity vk and the momentum-dependent scattering rateτ-1(εk). Unlike the case at optimal doping in which the transport properties are dominated by the nodal quasi-particles (QPs), both the lifetime and the Fermi velocity of the QPs in the antinodal region near the Fermi surface increase remarkably for the heavily overdoped samples. Our fitting results indicate that the antinodal QPs tend to dominate the transport properties in heavily overdoped high-Tc cuprates.
 Select Simulation of Dynamics in Two-Dimensional Vortex Systems in Random Media ZHANG Wei, SUN Li-Zhen, LUO Meng-Bo Chin. Phys. Lett. 2009, 26 (2): 027402 .   DOI: 10.1088/0256-307X/26/2/027402 Abstract   PDF(pc) (482KB) ( 429 ) Dynamics in two-dimensional vortex systems with random pinning centres is investigated using molecular dynamical simulations. The driving force and temperature dependences of vortex velocity are investigated. Below the critical depinning force Fc, a creep motion of vortex is found at low temperature. At forces slightly above Fc, a part of vortices flow in winding channels at zero temperature. In the vortex channel flow region, we observe the abnormal behaviour of vortex dynamics: the velocity is roughly independent of temperature or even decreases with temperature at low temperatures. A phase diagram that describes different dynamics of vortices is presented.
 Select Mode-II Crack Problem for a Long Rectangular Slab of Superconductor under an Electromagnetic Force GAO Zhi-Wen, ZHOU You-He Chin. Phys. Lett. 2009, 26 (2): 027403 .   DOI: 10.1088/0256-307X/26/2/027403 Abstract   PDF(pc) (323KB) ( 669 ) We present a theoretical analysis to the fracture parameters of the large single domain YBCO superconductor with a tangential line crack under electromagnetic force. The mode-II fracture parameters are obtained due to coupled finite element and infinite element method, and the numerical results are conducted for two activation processes. For a zero-field cooling (ZFC) magnetization process, in the process of magnetic field descent, the larger the applied field is, the larger the stress intensity factors. In the case of field cooling (FC) magnetization process, the stress intensity factors have obvious differences between the two cases of bfc >1 and bfc≤1. Additionally, J-integral characteristic is obtained, and according to these results, the mode-II crack growth trend is predicted. These results are benefit for us to understand the fracture mechanism of superconductor both in theory and application.
 Select Stability Investigation of Colloidal FePt Nanoparticle Systems by Spectrophotometer Analysis M. Farahmandjou, S. A. Sebt, S. S. Parhizgar, P. Aberomand, M. Akhavan Chin. Phys. Lett. 2009, 26 (2): 027501 .   DOI: 10.1088/0256-307X/26/2/027501 Abstract   PDF(pc) (336KB) ( 655 ) FePt magnetic nanoparticle systems are an excellent candidate for ultrahigh-density magnetic recording. Monodisperse FePt nanoparticles are synthesized by superhydride reduction of FeCl2・4H2O and Pt(acac)2 at 263°C under N2 atmosphere. Transmission electron microscopy (TEM) images show monosize FePt nanoparticles with diameter of 4nm and a standard deviation of about 10%. The average distance between monodispesre particles is nearly 3nm, and oleic acid and oleylamine surround the nanoparticles as surfactants. Stability investigation of nanoparticle colloidal solution is done via spectrophotometery analysis. The results for FePt nanoparticles dispersed in hexane indicate that adding surfactants with concentration of 3×10-3 part by volume for centrifugation stage increases the stability of FePt nanoparticles solution with concentration of 16mg/mL, about 67%.
 Select Magnetic Properties and Antiferromagnetic Coupling in Inhomogeneous Zn1-xFexO Magnetic Semiconductor DENG Jiang-Xia, YAN Shi-Shen, MEI Liang-Mo, J. P. Liu, B. Altuncevahir, V. Chakka, WANG Yong, ZHANG Ze, SUN Xiang-Cheng, J. Lian, K. Sun Chin. Phys. Lett. 2009, 26 (2): 027502 .   DOI: 10.1088/0256-307X/26/2/027502 Abstract   PDF(pc) (485KB) ( 460 ) Zn1-xFexO inhomogeneous oxide magnetic semiconductor films with high Fe concentration are prepared by sputtering, and fast annealing is carried out at different temperatures. It is found that magnetic properties are greatly modulated by controlling the composition inhomogeneity and subsequently fast annealing. Both ferromagnetic and paramagnetic components are found to coexist in the as-deposited Zn1-xFexO magnetic semiconductor. In particular, the antiferromagnetic coupling between the neighbouring local ferromagnetic regions is found in the as-deposited Zn0.23Fe0.77O film, and the antiferromagnetic coupling strength increases with increasing temperature from 110K to 300K. We believe that this unusual antiferromagnetic coupling is mediated by thermally activated hopping carriers.
 Select KNN Based Lead-Free Piezoceramics with Improved Thermal Stability DU Juan, WANG Jin-Feng, ZHENG Li-Mei, WANG Chun-Ming, QI Peng, ZANG Guo-Zhong Chin. Phys. Lett. 2009, 26 (2): 027701 .   DOI: 10.1088/0256-307X/26/2/027701 Abstract   PDF(pc) (558KB) ( 928 ) Lead-free piezoelectric ceramics (1-x)(Na0.53K0.404Li0.066)Nb0.92Sb0.08O3+xSrTiO3 are fabricated by conventional solid-state sintering method, and their dielectric and piezoelectric characteristics are investigated. With the addition of SrTiO3, the growth of the grain size is restrained, meanwhile the phase transition temperature of orthorhombic-tetragonal is shifted below room temperature. It is found that the ceramics with x=0.010 exhibit excellent piezoelectric properties (d33=220pC/N, kp=41%, kt=39%) and improved thermal stability around room temperature. The results indicate that these materials are promising lead-free piezoceramics for practical operations.
 Select Characteristics Analysis of Vertical Double Gate Strained Channel Heterostructure Metal-Oxide-Semiconductor-Field-Effect-Transistor YANG Yuan, LI Gui-Ping, GAO Yong, LIU Jing Chin. Phys. Lett. 2009, 26 (2): 027801 .   DOI: 10.1088/0256-307X/26/2/027801 Abstract   PDF(pc) (308KB) ( 540 ) Since device feature size shrinks continuously, there appears various short-channel effects on the fabrication and performance of devices and integrated circuits. We present a vertical double gate (VDG) strained channel heterostructure metal-oxide-semiconductor-field-effect-transistor (MOSFET). The electrical characteristics of the device with the effective gate length scaled down to 60nm are simulated. The results show that the drive current and transconductance are improved by 57.92% and 54.53% respectively, and grid swing is decreased by 36.83% over their unstrained counterparts. VDG MOSFETs exhibit a stronger capability to restrict short-channel-effects over traditional MOSFETs.
 Select Optical and Electrical Properties Evolution of Diamond-Like Carbon Thin Films with Deposition Temperature DING Xu-Li, LI Qing-Shan, KONG Xiang-He Chin. Phys. Lett. 2009, 26 (2): 027802 .   DOI: 10.1088/0256-307X/26/2/027802 Abstract   PDF(pc) (328KB) ( 1826 ) Optical and electrical properties of diamond-like carbon (DLC) films deposited by pulsed laser ablation of graphite target at different substrate temperatures are reported. By varying the deposition temperature from 400 to 25°C, the film optical transparency and electrical resistivity increase severely. Most importantly, the transparency and resistivity properties of the DLC films can be tailored to approaching diamond by adjusting the deposition temperature, which is critical to many applications. DLC films deposited at low temperatures show excellent optical transmittance and high resistivity. Over the same temperature regime an increase of the sp3 bonded C content is observed using visible Raman spectroscopy, which is responsible for the enhanced transparency and resistivity properties
CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY
 Select Enhanced Photoluminescence of InGaN/GaN Green Light-Emitting Diodes Grown on Patterned Sapphire Substrate PEI Xiao-Jiang, GUO Li-Wei, WANG Xiao-Hui, WANG Yang, JIA Hai-Qiang, CHEN Hong, ZHOU Jun-Ming Chin. Phys. Lett. 2009, 26 (2): 028101 .   DOI: 10.1088/0256-307X/26/2/028101 Abstract   PDF(pc) (405KB) ( 1140 ) Green InGaN/GaN based light-emitting diodes (LEDs) are fabricated both on planar and wet-etched patterned sapphire substrates by metalorganic vapour phase epitaxy (MOVPE). Their photoluminescence (PL) properties of the two samples are studied. The results indicate that the PL integral intensity of the green LED on the patterned substrate is nearly two times of that on the planar one within the whole measured temperature range. The enhanced PL intensity in the green LED on the patterned substrate is shown completely contributed from the extraction efficiency, but not from the internal quantum efficiency. The conclusion is supported by temperature-dependent PL analysis on the two samples, and the mechanisms are discussed..
 Select GaAs Based InAs/GaSb Superlattice Short Wavelength Infrared Detectors Grown by Molecular Beam Epitaxy TANG Bao, XU Ying-Qiang, ZHOU Zhi-Qiang, HAO Rui-Ting, WANG Guo-Wei, REN Zheng-Wei, NIU Zhi-Chuan Chin. Phys. Lett. 2009, 26 (2): 028102 .   DOI: 10.1088/0256-307X/26/2/028102 Abstract   PDF(pc) (415KB) ( 818 ) InAs/GaSb superlattice (SL) short wavelength infrared photoconduction detectors are grown by molecular beam epitaxy on GaAs(001) semi-insulating substrates. An interfacial misfit mode AlSb quantum dot layer and a thick GaSb layer are grown as buffer layers. The detectors containing a 200-period 2ML/8ML InAs/GaSb SL active layer are fabricated with a pixel area of 800×800μm2 without using passivation or antireflection coatings. Corresponding to the 50% cutoff wavelengths of 2.05μm at 77K and 2.25μ,m at 300K, the peak detectivities of the detectors are 4×109cm・Hz1/2/W at 77K and 2×108cm・Hz1/2/W at 300K, respectively
 Select Cation Effect on Copper Chemical Mechanical Polishing WANG Liang-Yong, LIU Bo, SONG Zhi-Tang, FENG Song-Lin Chin. Phys. Lett. 2009, 26 (2): 028103 .   DOI: 10.1088/0256-307X/26/2/028103 Abstract   PDF(pc) (383KB) ( 1096 ) We examine the effect of cations in solutions containing benzotriazole (BTA) and H2O2 on copper chemical mechanical polishing (CMP). On the base of atomic force microscopy (AFM) and material removal rate (MRR) results, it is found that ammonia shows the highest MRR as well as good surface after CMP, while KOH demonstrates the worst performance. These results reveal a mechanism that small molecules with lone-pairs rather than molecules with steric effect and common inorganic cations are better for copper CMP process, which is indirectly confirmed by open circuit potential (OCP).
 Select Finite Element Analysis of Convection in Growth Cell for Diamond Growth Using Ni-Based Solvent TIAN Yu, JIA Xiao-Peng, ZANG Chuan-Yi, LI Rui, LI Shang-Sheng, XIAO Hong-Yu, ZHANG Ya-Fei, HUANG Guo-Feng, HAN Qi-Gang, MA Li-Qiu, LI Yong, CHEN Xiao-Zhou, ZHANG Cong, MA Hong-An Chin. Phys. Lett. 2009, 26 (2): 028104 .   DOI: 10.1088/0256-307X/26/2/028104 Abstract   PDF(pc) (607KB) ( 543 ) Thermal-electrical-fluid coupled finite element analyses are performed in the model of the growth cell in a high-pressure and high-temperature (HPHT) cubic apparatus in which the large diamond crystal can be grown by using Ni-based solvent with temperature gradient method (TGM). The convection in the Ni-based solvent with different thicknesses at 1700-1800K is simulated by finite element method (FEM). The experiments of diamond crystal growth are also carried out by using Ni-based solvent at 5.7GPa and 1700-1800K in a China-type cubic high pressure apparatus (CHPA). The simulation results show that the Rayleigh number in the solvent is enhanced obviously with the increasing solvent thickness. Good quality diamond single crystal cannot be grown if the Rayleigh number in the solvent is too high.
 Select Experimental Test of 7.8GHz Power Extractor Using Dielectric Loaded Rectangular Waveguide Structures LU Zhi-Gang, GONG Yu-Bin, GAI Wei, GAO Peng, GAO Feng, WEI Yan-Yu, WANG Wen-Xiang Chin. Phys. Lett. 2009, 26 (2): 028401 .   DOI: 10.1088/0256-307X/26/2/028401 Abstract   PDF(pc) (370KB) ( 447 ) We report on experimental test of a 7.8GHz power extractor using a dielectric loaded rectangular waveguide structure. This work is conducted at the Argonne wakefield accelerator (AWA) facility. The wakefield is excited by an electron beam travelling through a dielectric loaded rectangular waveguide, and the generated rf power is then subsequently extracted with a properly designed rf coupler. In the experiment, 30MW of output power is excited by a 66nC single electron bunch, and wakefield superposition by a train consisting of four bunches is also demonstrated. Both the results agree well with theoretical predictions
 Select Robust and Adaptive MicroRNA-Mediated Incoherent Feedforward Motifs XU Feng-Dan, LIU Zeng-Rong, ZHANG Zhi-Yong, SHEN Jian-Wei, Chin. Phys. Lett. 2009, 26 (2): 028701 .   DOI: 10.1088/0256-307X/26/2/028701 Abstract   PDF(pc) (261KB) ( 417 ) We integrate transcriptional and post-transcriptional regulation into microRNA-mediated incoherent feedforward motifs and analyse their dynamical behaviour and functions. The analysis show that the behaviour of the system is almost uninfluenced by the varying input in certain ranges and by introducing of delay and noise. The results indicate that microRNA-mediated incoherent feedforward motifs greatly enhance the robustness of gene regulation.
 Select Generalized Synchronization of Time-Delayed Differential Systems JING Jian-Yi, MIN Le-Quan, Chin. Phys. Lett. 2009, 26 (2): 028702 .   DOI: 10.1088/0256-307X/26/2/028702 Abstract   PDF(pc) (301KB) ( 541 ) We establish two theorems for two time-delayed (chaotic) differential equation systems to achieve time-delayed generalized synchronization (TDGS). The theorems uncover general forms of two TDGS systems via a prescribed differentiable transformation. Based on the theorems, we use two-coupled Ikeda equations as the driving system to construct TDGS driven systems via two prescribed transformations. Numerical simulations demonstrate the effectiveness of the proposed theorems. It may be expected that our theorems provide new tools for understanding and studying TDGS phenomena.
 Select Thermal Vibration and Twist Induced Semiconducting Behaviour in Short DNA Wires WU Zheng-Yi, FENG Jin-Fu, WU Xiao-Shan Chin. Phys. Lett. 2009, 26 (2): 028703 .   DOI: 10.1088/0256-307X/26/2/028703 Abstract   PDF(pc) (273KB) ( 363 ) We study the transport properties of electrons in a short homogeneous DNA molecule where thermal vibrations and twist fluctuations of the base molecules are considered. The nonlinear current-voltage curves can be derived by using the equivalent single-particle multichannel network. The voltage gap is sensitive to the strength of thermal vibrations and twist fluctuations of the base molecules. Our results are in good agreement with the recent finding of semiconducting behaviour in short poly(G)-poly(C) DNA oligomers. The present method can also be used to calculate the other molecular wires
 Select Direct Evidence for Inversion Formula in Multifractal Financial Volatility Measure JIANG Zhi-Qiang, , ZHOU Wei-Xing, , Chin. Phys. Lett. 2009, 26 (2): 028901 .   DOI: 10.1088/0256-307X/26/2/028901 Abstract   PDF(pc) (275KB) ( 723 ) The inversion formula for conservative multifractal measures was unveiled mathematically a decade ago, which is however not well tested in real complex systems. We propose to verify the inversion formula using high-frequency turbulent financial data. We construct conservative volatility measure based on minutely S&P 500 index from 1982 to 1999 and its inverse measure of exit time. Both the direct and inverse measures exhibit nice multifractal nature, whose scaling ranges are not irrelevant. Empirical investigation shows that the inversion formula holds in financial markets.
 Select Heavy-Tailed Statistics in Short-Message Communication HONG Wei, HAN Xiao-Pu, ZHOU Tao, WANG Bing-Hong, Chin. Phys. Lett. 2009, 26 (2): 028902 .   DOI: 10.1088/0256-307X/26/2/028902 Abstract   PDF(pc) (332KB) ( 558 ) Short-message (SM) is one of the most frequently used communication channels in modern society. Based on the SM communication records provided by some volunteers, we investigate the statistics of SM communication pattern, including the inter-event time distributions between two consecutive short messages and two conversations, and the distribution of message number contained in a complete conversation. In the individual level, the empirical result raises strong evidence that the human activity pattern, exhibiting a heavy-tailed inter-event time distribution, is driven by a non-Poisson process.
GEOPHYSICS, ASTRONOMY, AND ASTROPHYSICS
 Select Physical Explanation of Influence of Twin and Three Satellite Formation Mode on the Accuracy of Earth's Gravitational Field ZHENG Wei, XU Hou-Ze, ZHONG Min, YUN Mei-Juan Chin. Phys. Lett. 2009, 26 (2): 029101 .   DOI: 10.1088/0256-307X/26/2/029101 Abstract   PDF(pc) (238KB) ( 537 ) The simulated results of the influence of twin and three satellite formation mode on the accuracy of GRACE Earth's gravitational field are interpreted from the viewpoint of physics. Because the effective satellite observation information of Earth's gravitational field recovery from three-satellite formation mode is only one time more than that of twin satellites, the improvement of the accuracy of Earth's gravitational field is far lower than one order of magnitude based on the simple two-times differences between three satellites. Three efficient ways of improving largely the accuracy of measurement of the Earth's gravitational field in the future international satellite gravity measurement programme, including proper decrease of satellite orbital altitude, the increase of accuracy from key payloads and an innovation of satellite observation mode are proposed.
 Select Properties of Field Aligned Current in Plasma Sheet Boundary Layers in Magnetotail: Cluster Observation SHI Jian-Kui, CHENG Zheng-Wei, T. L. Zhang, M. Dunlop, LIU Zhen-Xing Chin. Phys. Lett. 2009, 26 (2): 029401 .   DOI: 10.1088/0256-307X/26/2/029401 Abstract   PDF(pc) (250KB) ( 616 ) Field aligned current (FAC) distribution in the plasma sheet boundary layers (PSBLs) in the magnetotail is studied statistically by analysing magnetic field data from the Cluster 4-point measurements. The results show that the FAC distribution on the dusk side is not the same as that on the dawn side in the magnetotail. On the each side earthward and tailward, FAC occurrences are different; occurrence and average current density of FACs in the northern hemisphere are different from those in the southern hemisphere. This implies that the FACs have dusk-dawn side asymmetry, polarity asymmetry and inter hemisphere difference in the magnetotail. The present results give a good observation evidence for study on the FAC mechanism.
 Select Interacting Holographic Dark Energy in the Scalar Gauss-Bonnet Gravity M. R. Setare Chin. Phys. Lett. 2009, 26 (2): 029501 .   DOI: 10.1088/0256-307X/26/2/029501 Abstract   PDF(pc) (164KB) ( 428 ) We study cosmological application of interacting holographic dark energy density in the scalar Gauss-Bonnet framework. We employ the interacting holographic model of dark energy to obtain the equation of state for the interacting holographic energy density in a spatially flat universe. Our calculations show that taking ΩΛ=0.73 for the present time, it is possible to have wΛeff crossing -1. This implies that one can generate a phantom-like equation of state from the interacting holographic dark energy model in flat universe in the scalar Gauss-Bonnet cosmology framework. Then we reconstruct the potential of the scalar field.
 Select Mass of Open Cluster NGC 7789 WU Zhen-Yu, DU Cui-Hua, MA Jun, ZHOU Xu Chin. Phys. Lett. 2009, 26 (2): 029701 .   DOI: 10.1088/0256-307X/26/2/029701 Abstract   PDF(pc) (297KB) ( 375 ) Mass of open cluster NGC 7789 in the Galaxy is determined by three methods: the photometric method based on mass-luminosity relations of stars in the cluster Mpho=7712.5M⊙; the dynamical method based on virial theorem Mvir=6996.1M⊙; and the tidal radius method based on the interaction between the cluster and the Galaxy Mtid=5152.5M⊙. The mean mass of this cluster is estimated to be Mc=6620.4±762.5M⊙.
Original Articles
 Select Evolution of Holographic Dark Energy in Interacting Modified Chaplygin Gas Model WANG Cong, WU Ya-Bo, LIU Fei Chin. Phys. Lett. 2009, 26 (2): 029801 .   DOI: 10.1088/0256-307X/26/2/029801 Abstract   PDF(pc) (300KB) ( 400 ) We investigate the modified Chaplygin gas (MCG) with interaction between holographic dark energy proposed by Li and dark matter. In this model, evolution of the universe is described in detail, which is from deceleration to acceleration. Specifically, the evolutions of related cosmological quantities such as density parameter, the equation of state of holographic dark energy, deceleration parameter and transition redshift are discussed. Moreover, we also give their present values which are consistent with the lately observations. Furthermore, the results given by us show such a model can accommodate a transition of the dark energy from a normal state wX>-1 to wX<-1 phantom regimes.
 Select Bianchi Type III Bulk Viscous Barotropic Fluid Cosmological Models with Variable G and Λ Raj Bali, Seema Tinker Chin. Phys. Lett. 2009, 26 (2): 029802 .   DOI: 10.1088/0256-307X/26/2/029802 Abstract   PDF(pc) (191KB) ( 607 ) Bianchi type-III bulk viscous barotropic fluid cosmological model with variables G and Λ is investigated. To obtain the realistic model, we assume the conditions between the metric potentials A, B, C as ・A/A=・B/B=m1/tn and ・C/C=m2/tn, P=p-3ηH,η=η0 ρs, p =γρ, 0≤γ≤1, where p is isotropic pressure, η the coefficient of bulk viscosity, η0 and S the constants, H the Hubble constant, m1= 2m2 where m1>0, m2>0. The solutions obtained lead to inflationary phase and the results obtained match with the observations. The case n=1 for S=1 is also discussed, relating the results with the observations.
87 articles