2013年, 第60卷, 第02期　
刊出日期：2013-08-15

  

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  Generating a New Higher-Dimensional Coupled Integrable Dispersionless System: Algebraic Structures, Bäcklund Transformation and Hidden Structural Symmetries

  Souleymanou Abbagari, Thomas B. Bouetou, Timoleon C. Kofane

  理论物理通讯. 2013, 60(02): 145-149.

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  The prolongation structure methodologies of Wahlquist-Estabrook [H.D. Wahlquist and F.B. Estabrook, {J. Math. Phys.} 16 (1975) 1] for nonlinear differential equations are applied to a more general set of coupled integrable dispersionless system. Based on the obtained prolongation structure, a Lie-Algebra valued connection of a closed ideal of exterior differential forms related to the above system is constructed. A Lie-Algebra representation of some hidden structural symmetries of the previous system, its Bäcklund transformation using the Riccati form of the linear eigenvalue problem and their general corresponding Lax-representation are derived. In the wake of the previous results, we extend the above prolongation scheme to higher-dimensional systems from which a new (2+1)-dimensional coupled integrable dispersionless system is unveiled along with its inverse scattering formulation, which applications are straightforward in nonlinear optics where additional propagating dimension deserves some attention.
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  Dynamics of the Manakov Solitons in Biased Guest-Host Photorefractive Polymer

  谭钊, 田播, 江彦, 王盼, 李敏

  理论物理通讯. 2013, 60(02): 150-158.

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  In the biased guest-host photorefractive polymer, the Manakov equations can be used to describe the optical soliton propagation and interaction. Hereby for such equations, via the Hirota method and symbolic computation, analytic soliton solutions in the bright-dark and dark-dark forms are obtained. Based on the choice of photorefractive polymer parameter and incident-optical-beam parameter, the bright-dark and dark-dark solitons as well as their interaction can occur in the polymer when the total intensity is much lower than the background illumination, and our analysis indicates that the incident light with different polarization directions influence little on the soliton propagation. γ, representing the soliton intensity far away from the soliton center, determines the appearance of bright or dark soliton under the background illumination. Through the graphic and asymptotic analysis on the two-soliton solutions along with the different γ, we find that there exist the elastic and inelastic interactions between the bright-dark solitons, while the interactions between the dark-dark solitons are always elastic.
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  Adomian Decomposition Method Using Integrating Factor

  Yinwei Lin, Tzon-Tzer Lu, Cha'o-Kuang Chen

  理论物理通讯. 2013, 60(02): 159-164.

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  This paper proposes a new Adomian decomposition method by using integrating factor. Nonlinear models are solved by this method to get more reliable and efficient numerical results. It can also solve ordinary differential equations where the traditional one fails. Besides, the complete error analysis for this method is presented.
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  Single-Qubit Operation Sharing with Bell and W Product States

  季启彬, 刘益民, 刘先松, 尹晓峰, 张战军

  理论物理通讯. 2013, 60(02): 165-170.

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  Two tripartite schemes are put forward with shared entanglements and Local Operation and Classical Communication (LOCC) for sharing an operation on a remote target sate. The first scheme uses a Bell and a symmetric W states as quantum channels, while the second replaces the symmetric W state by an asymmetric one. Both schemes are treated and compared from the aspects of quantum resource consumption, operation complexity, classical resource consumption, success probability and efficiency. It is found that the latter scheme is better than the former one. Particularly, the sharing can be achieved only probabilistically with the first scheme deterministically with the second one.
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  Effects of Quantum Correction on Dynamical Phase Transition in a Single Species Bosonic Josephson Junction

  田静, 邱海波

  理论物理通讯. 2013, 60(02): 171-174.

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  In this paper, by employing Bogliubov backreaction method, we investigate quantum correction effects on dynamical phase transition in a single species bosonic Josephson junction induced by increasing nonlinear interaction. Compared with mean field theory results, we find that the transition point is shifted. The dynamical phase transition is accompanied by a change of the entanglement entropy, which is found to reach a maximum at the transition point of the mean field theory.
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  Painlevé Analysis, Lie Symmetries and Exact Solutions for Variable Coefficients Benjamin-Bona-Mahony-Burger (BBMB) Equation

  Vikas Kumar, R.K. Gupta, Ram Jiwari

  理论物理通讯. 2013, 60(02): 175-182.

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  In this paper, a variable-coefficient Benjamin-Bona-Mahony-Burger (BBMB) equation arising as a mathematical model of propagation of small-amplitude long waves in nonlinear dispersive media is investigated. The integrability of such an equation is studied with Painlevé analysis. The Lie symmetry method is performed for the BBMB equation and then similarity reductions and exact solutions are obtained based on the optimal system method. Furthermore different types of solitary, periodic and kink waves can be seen with the change of variable coefficients.
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  Reconstruction of Scalar Field Dark Energy Models in Kaluza-Klein Universe

  M. Sharif, Abdul Jawad

  理论物理通讯. 2013, 60(02): 183-188.

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  This paper is devoted to study the modified holographic dark energy model by taking its different aspects in the flat Kaluza-Klein universe. We construct the equation of state parameter which evolutes the universe from quintessence region towards the vacuum. It is found that the modified holographic model exhibits instability against small perturbations in the early epoch of the universe but becomes stable in the later times. We also develop its correspondence with some scalar field dark energy models. It is interesting to mention here that all the results are consistent with the present observations.
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  Finite-Time Stability of Fractional-Order Neural Networks with Delay

  吴然超, 黑鑫东, 陈立平

  理论物理通讯. 2013, 60(02): 189-193.

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  Finite-time stability of a class of fractional-order neural networks is investigated in this paper. By Laplace transform, the generalized Gronwall inequality and estimates of Mittag-Leffler functions, sufficient conditions are presented to ensure the finite-time stability of such neural models with the Caputo fractional derivatives. Furthermore, results about asymptotical stability of fractional-order neural models are also obtained.
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  Darboux Transformation and Soliton Solutions for the (2+1)-Dimensional Generalization of Shallow Water Wave Equation with Symbolic Computation

  闻小永, 孟祥花

  理论物理通讯. 2013, 60(02): 194-200.

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  In this paper, the (2+1)-dimensional generalization of shallow water wave equation, which may be used to describe the propagation of ocean waves, is analytically investigated. With the aid of symbolic computation, we prove that the (2+1)-dimensional generalization of shallow water wave equation possesses the Painlevé property under a certain condition, and its Lax pair is constructed by applying the singular manifold method. Based on the obtained Lax representation, the Darboux transformation (DT) is constructed. The first iterated solution, second iterated solution and a special N-soliton solution with an arbitrary function are derived with the resulting DT. Relevant properties are graphically illustrated, which might be helpful to understanding the propagation processes for ocean waves in shallow water.
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  The Effects of Simplest Little Higgs Model on the Spin Correlations in the Top Quark Pair Production at the LHC and ILC

  韩小芳, 史文谱, 王磊

  理论物理通讯. 2013, 60(02): 201-204.

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  In the simplest little Higgs model (SLH), we study the spin correlations in the top quark pair production at the LHC and ILC. We find that the SLH always suppresses the tt spin correlations compared to the SM values. At the LHC, the suppression can be over 10% for m_Z' < 750 GeV. The SLH prediction value is outside the 1σ range of the experimental data from ATLAS, and within 1σ range of the experimental data from CMS. At the ILC, the SLH can sizably suppress the tt spin correlation for m_Z' approaching the center-of-mass energy √s. For example, the maximal suppression can reach -22.5%, -14.5%, and -9.5% for √s=500 GeV, 800 GeV, and 1000 GeV, respectively. Therefore, the tt spin correlation at the ILC can be a sensitive probe for the SLH.
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  Detection of Charged Higgs Bosons in e⁺e^-(γγ)→tbφ^- Production at the ILC

  韩金钟, 李炳中

  理论物理通讯. 2013, 60(02): 205-209.

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  In the context of the left-right twin Higgs (LRTH) model, we have studied the charged Higgs bosons production processes e⁺e^-(γγ)→tbφ^- at the International Linear Collider (ILC). It is found that the cross sections of these two processes could reach a few fb with reasonable parameter values. With the yearly integrated luminosity of L=500 fb^-1 expected at the ILC, one could collect hundreds up to thousands of charged Higgs events via these two processes. Therefore, our researches in this paper can help us search for charged Higgs bosons, and furthermore, to test the LRTH model.
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  Dynamical Entanglement of Vibrations in Integrable Dimer and Small Molecules

  张金利, 刘金明

  理论物理通讯. 2013, 60(02): 210-216.

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  By means of the reduced-density linear entropy, we investigate the properties of dynamical entanglement of vibrations in integrable dimer and realistic small molecules which are initially in the two-mode squeezed vacuum state. It is found that the entropy of the integrable dimer is periodic for weak coupling strength c₁ and small squeezing parameter r, and there exists a beat phenomenon for strong c₁ and large r. Moreover, the entropy of the small molecules is quasi-periodic for small r, and the beat phenomenon occurs in the entropy evolution of the two molecules C₂D₂ and SO₂ for large r. Our results might be used for molecular quantum computing based on vibrational states.
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  Emission Spectrum Property of Modulated Atom-Field Coupling System

  高云峰, 冯健, 李悦科

  理论物理通讯. 2013, 60(02): 217-221.

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  The emission spectrum of a two-level atom interacting with a single mode radiation field in the case of periodic oscillation coupling coefficient is investigated. A general expression for the emission spectrum is derived. The numerical results for the initial field in pure number stare are calculated. It is found that the effect of the coupling coefficient modulation on the spectral structure is very obvious in the case of a low modulation frequency and larger amplitude when the initial field is vacuum, which is potentially useful for exploring a modulated light source.
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  Effects of Higher-Order Relativistic Nonlinearity and Wakefield During a Moderately Intense Laser Pulse Propagation in a Plasma Channel

  刘明萍, 刘兵兵, 刘三秋, 张福阳, 刘杰

  理论物理通讯. 2013, 60(02): 222-226.

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  Using a variational approach, the propagation of a moderately intense laser pulse in a parabolic preformed plasma channel is investigated. The effects of higher-order relativistic nonlinearity (HRN) and wakefield are included. The effect of HRN serves as an additional defocusing mechanism and has the same order of magnitude in the spot size as that of the transverse wakefield (TWF). The effect of longitudinal wakefield is much larger than those of HRN and TWF for an intense laser pulse with the pulse length equaling the plasma wavelength. The catastrophic focusing of the laser spot size would be prevented in the present of HRN and then it varies with periodic focusing oscillations.
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  Spherical Kadomtsev-Petviashvili Solitons in a Suprathermal Complex Plasma

  Mehran Shahmansouri, Jafar Borhanian

  理论物理通讯. 2013, 60(02): 227-232.

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  The nonlinear aspects of nonplanar dust acoustic (DA) solitary waves are investigated in an unmagnetized complex plasma comprising of cold dust grains, kappa-distributed ions as well as electrons. The nonplanar DA solitons are studied based on the reductive perturbation technique. It is shown that the evolution of DA solitons is governed by a spherical Kadomtsev-Petviashvili (sKP) equation and then the impact of suprathermality on the spatial structure as well as the nature of DA soliton is studied. It seems that the properties of DA solitons in nonplanar geometry are quite different from that of the planar solitons.
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  First-principles Study on the Magnetic, Half-metal and Thermoelectric Transport Properties of Inorganic-Organic Hybrid Compounds [C₄N₂H₁₂][Fe₄^Ⅲ(HPO₃)₂(C₂O₄)₃]

  李艳丽, 张典娜

  理论物理通讯. 2013, 60(02): 233-239.

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  The electronic structure, magnetic and half-metal properties of inorganic-organic hybrid compound [C₄N₂H₁₂][Fe₄^Ⅲ(HPO₃)₂(C₂O₄)₃] are investigated by using the full-potential linearized augmented plane wave (FPLAPW) method within density-functional theory (DFT) calculations. The density of states (DOS), the total energy of the cell and the spontaneous magnetic moment of [C₄N₂H₁₂][Fe₄^Ⅱ(HPO₃)₂(C₂O₄)₃] are calculated. The calculation results reveal that the low-temperature phase of [C₄N₂H₁₂][Fe₄^Ⅲ(HPO₃)₂(C₂O₄)₃] exhibits a stable ferromagnetic (FM) ground state, and we find that this organic compound is a half-metal in FM state. In addition, we have calculated antiferromagnetically coupled interactions, revealing the existence of antiferromagnetic (AFM), which is in agreement with the experiment. We have also found that [C₄N₂H₁₂][Fe₄^Ⅲ(HPO₃)₂(C₂O₄)₃] is a semiconductor in the AFM state with a band gap of about 0.40 eV. Subsequently, the transport properties for potential thermoelectric applications have been studied in detail based on the Boltzmann transport theory.
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  Effects of Bond Alternation on the Ground-State Phase Diagram of One-Dimensional XXZ Model

  强凌, 刘光华, 田光善

  理论物理通讯. 2013, 60(02): 240-246.

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  The ground-state properties and quantum phase transitions (QPTs) of the one-dimensional bond-alternative XXZ model are investigated by the infinite time-evolving block decimation (iTEBD) method. The bond-alternative effects on its ground-state phase diagram are discussed in detail. Once the bond alternation is taken into account, the antiferromagnetic phase (Δ > 1) will be destroyed at a given critical point and change into a disordered phase without nonlocal string order. The QPT is shown to be second-order, and the whole phase diagram is provided. For the ferromagnetic phase region (Δ < -1), the critical point r^c always equals 1 (independent of Δ), and the QPT for this case is shown to be first-order. The dimerized Heisenberg model is also discussed, and two disordered phases can be distinguished by with or without nonlocal string orders. Both the bipartite entanglement and the fidelity per site, as two kinds of model-independent measures, are capable of describing all the QPTs in such a quantum model.
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  Reduction of Protein Networks Models by Passivity Preserving Projection

  Luca Mesin, Flavio Canavero, Lamberto Rondoni

  理论物理通讯. 2013, 60(02): 247-257.

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  Reduction of complex protein networks models is of great importance. The accuracy of a passivity preserving algorithm (PRIMA) for model order reduction (MOR) is here tested on protein networks, introducing innovative variations of the standard PRIMA method to fit the problem at hand. The reduction method does not require to solve the complete system, resulting in a promising tool for studying very large-scale models for which the full solution cannot be computed. The mathematical structure of the considered kinetic equations is preserved. Keeping constant the reduction factor, the approximation error is lower for larger systems.
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  Detecting Communities by Revised Max-flow Method in Networks

  刘传建, 朱志强, 吴建良

  理论物理通讯. 2013, 60(02): 258-262.

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  A ubiquitous phenomenon in networks is the presence of communities within which the network connections are dense and between which they are sparser. This paper proposes a max-flow algorithm in bipartite networks to detect communities in general networks. Firstly, we construct a bipartite network in accordance with a general network and derive a revised max-flow problem in order to uncover the community structure. Then we present a local heuristic algorithm to find the optimal solution of the revised max-flow problem. This method is applied to a variety of real-world and artificial complex networks, and the partition results confirm its effectiveness and accuracy.