2013年, 第60卷, 第04期　
刊出日期：2013-10-15

  

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  Interactions Between Solitons and Cnoidal Periodic Waves of the Boussinesq Equation

  杨铎, 楼森岳, 余炜沣

  理论物理通讯. 2013, 60(04): 387-390.

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  The Boussinesq equation is one of important prototypic models in nonlinear physics. Various nonlinear excitations of the Boussinesq equation have been found by many methods. However, it is very difficult to find interaction solutions among different types of nonlinear excitations. In this peper, two equivalent very simple methods, the truncated Painlevé analysis and the generalized tanh function expansion approaches, are developed to find interaction solutions between solitons and any other types of Boussinesq waves.
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  Quantum Correlations in a Two-Qubit Heisenberg XX Model under Intrinsic Decoherence

  仇亮

  理论物理通讯. 2013, 60(04): 391-396.

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  Taking into account the intrinsic decoherence, we have investigated quantum correlations in a two-qubit Heisenberg XX model when a nonuniform magnetic field is included. We compare entanglement measured by entanglement of formation, quantum discord and measurement-induced measurement (MID) and illustrate their different characteristics. Quantum discord and MID show the same features and always exist even though there is no entanglement in the long time limit. In the time evolution, quantum discord could be generated or enhanced to the stable value, while MID just decreases to the stable value.
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  A Novel Deterministic Secure Quantum Communication Scheme with Einstein-Podolsky-Rosen Pairs and Single Photons

  王朝, 刘建伟, 刘潇, 尚涛

  理论物理通讯. 2013, 60(04): 397-404.

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  A novel deterministic secure quantum communication (DSQC) scheme is presented based on Einstein-Podolsky-Rosen (EPR) pairs and single photons in this study. In this scheme, the secret message can be encoded directly on the first particles of the prepared Bell states by simple unitary operations and decoded by performing the Bell-basis measurement after the additional classic information is exchanged. In addition, the strategy with two-step transmission of quantum data blocks and the technique of decoy-particle checking both are exploited to guarantee the security of the communication. Compared with some previous DSQC schemes, this scheme not only has a higher resource capacity, intrinsic efficiency and total efficiency, but also is more realizable in practical applications. Security analysis shows that the proposed scheme is unconditionally secure against various attacks over an ideal quantum channel and still conditionally robust over a noisy and lossy quantum channel.
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  Quantum Correlations in Werner Derivatives

  王胜房, 刘益民, 李国锋, 刘先松, 张战军

  理论物理通讯. 2013, 60(04): 405-409.

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  Quantum correlations in Werner derivatives are studied with two different approaches, i.e., measurement-induced disturbance (MID) [Phys. Rev. A 77 (2008) 022301] and ameliorated MID (AMID) [J. Phys. A 44 (2011) 352002]. They are derived via strict deductions with MID while numerically calculated via the measurement optimization with AMID. Interestingly, quantum correlations captured with both approaches are completely coincident. Moreover, some distinct features of the quantum correlations and their underlying physics are exposed via analyses and discussions.
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  Entanglement Dynamics of Quantum States Undergoing Decoherence from a Driven Critical Environment

  马小三, 乔莹, 刘晓东, 王安民

  理论物理通讯. 2013, 60(04): 410-414.

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  In this paper, we have investigated the quantum entanglement of quantum states undergoing decoherence from a spin environment which drives a quantum phase transition. From our analysis, we find that the entanglement dynamics depends not only on the coupling strength but also on the external magnetic field and the number of the freedom degrees of the environment. Specially, our results imply that the decay of the entanglement can be enhanced by the quantum phase transition of the environment when the system is coupled to the environment weakly. Additionally, the discussion of the case of the multipartite states with high dimensions is made.
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  Quantum Network Coding on Networks with Arbitrarily Distributed Hidden Channels

  张盛, 李洁, 董恒杰, 刘进

  理论物理通讯. 2013, 60(04): 415-420.

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  Although perfect quantum network coding has been proved to be achievable, it is still puzzling whether it is feasible whenever one or more of the channels are replaced by the hidden ones emerging from quantum entanglement. The question is answered in this paper. First, we propose a quantum network coding protocol over a butterfly network with two hidden channels. Second, we investigate a more general situation, where d-level quantum letters are transmitted through the network containing arbitrarily distributed hidden channels, and prove that quantum network coding on such networks is still achievable.
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  Efficient Multipartite Polarization Entanglement Distribution Over Arbitrary Noise Channel

  陈晓, 李艳, 曾志, 李熙涵

  理论物理通讯. 2013, 60(04): 421-426.

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  We present an efficient faithful multipartite polarization entanglement distribution protocol over an arbitrary noisy channel. The spatial degree of freedom is used to carry the entanglement during the transmission. We describe the principle by distributing n-qubit Greenberge-Horne-Zeilinger state and n-qubit W state. Our scheme can be used to distribute arbitrary n-qubit entangled states to n distant locations. The remote parties can obtain maximally entangled states deterministically on the polarization of photons. Only passive linear optics are employed in our setup, which makes our scheme more feasible and efficient for practical application in long distance quantum communication.
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  Information Loss for QCD Matter in AdS Black Holes at LHC

  A. Sepehri, M. E. Zomorrodian, S. Shoorvazi, M. Hasheminia

  理论物理通讯. 2013, 60(04): 427-432.

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  In this paper, we find the information loss for QCD matter in AdS black holes at LHC by extending the Gottesman and Preskill methode to AdS black holes. We calculate the information transformation from the collapsing matter to the state of outgoing Hawking radiation for both quarks and gluons. It is noticed that for finite values of quark and gluon energies, information from all emission processes experiences some degrees of loss. Possible explanation for this feature will be presented in this paper.
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  Dynamics of Charged Particles Around a Magnetized Black Hole with Pseudo-Newtonian Potential

  王颖, 伍歆, 孙威

  理论物理通讯. 2013, 60(04): 433-438.

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  The linear stability of equilibria of charged particles moving near a compact object with a dipole magnetic field and a pseudo-Newtonian potential is analyzed detailedly. An optimal fourth-order force gradient symplectic method, as a global symplectic integrator that can simultaneously solve both the equations of motion and the variational equations, is used to calculate fast Lyapunov indicators. In this way, dynamical structures are described, and parameter domains for causing chaos are found.
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  Drive Control of Spiral Wave and Turbulence by a Target Wave in CGLE

  向秀桥, 施保昌, 何耀耀

  理论物理通讯. 2013, 60(04): 439-444.

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  Suppression of spiral wave and turbulence in the complex Ginzburg-Landau equation (CGLE) plays a prominent role in nonlinear science and complex dynamical system. In this paper, the nonlinear behavior of the proposed drive-response system, which consists of two coupled CGLEs, is investigated and controlled by a state error feedback controller with the lattice Boltzmann method. First, spiral wave and turbulence are, respectively, generated by selecting appropriate parameters of the response system under the no-flux boundary and perpendicular gradient initial conditions. Then, based on the random initial condition, the target wave yielded by introducing spatially localized inhomogeneity into the drive system is applied on the above response system. The numerical simulation results show that the spiral wave and turbulence existing in the response system could be successfully eliminated by the target wave in the drive system during a short evolution time. Furthermore, it turns out that the transient time for the drive course is related to the control intensity imposed on the whole media.
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  Improved Speed and Shape of Ion-Acoustic Waves in a Warm Plasma

  H. G. Abdelwahed, E. K. El-Shewy

  理论物理通讯. 2013, 60(04): 445-452.

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  The basic set of fluid equations can be reduced to the nonlinear Kortewege-de Vries (KdV) and nonlinear Schrödinger (NLS) equations. The rational solutions for the two equations has been obtained. The exact amplitude of the nonlinear ion-acoustic solitary wave can be obtained directly without resorting to any successive approximation techniques by a direct analysis of the given field equations. The Sagdeev's potential is obtained in terms of ion acoustic velocity by simply solving an algebraic equation. The soliton and double layer solutions are obtained as a small amplitude approximation. A comparison between the exact soliton solution and that obtained from the reductive perturbation theory are also discussed.
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  Interference of Quantum Chaotic Systems in Phase Space

  徐酉阳

  理论物理通讯. 2013, 60(04): 453-457.

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  We investigate the interference of a kicked harmonic oscillator in phase space. With the measure of interference defined in Lee and Jeong [Phys. Rev. Lett. 106 (2011) 220401], we show that interference increases more rapidly in the chaotic regime than in the regular regime, and that the sub-Planck structure is of importance for the decoherence time in the chaotic regime. We also find that interference plays an important role in energy transport between the kicking fields and the kicked harmonic oscillator.
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  (n+1)-Dimensional Gravity Duals to Quantum Criticalities with Spontaneous Symmetry Breaking

  曾定方, 赵凯

  理论物理通讯. 2013, 60(04): 458-464.

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  We reexamine the charged AdS domain wall solution to the Einstein-Abelian-Higgs model proposed by Gubser et al. as holographic superconductors at quantum critical points and comment on their statement about the uniqueness of gravity solutions. We generalize their explorations from (3+1)-dimensions to arbitrary n+1Ds and find that the n+1≥qslant5D charged AdS domain walls are unstable against electric perturbations.
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  A Semi-Analytical Solution to Classic Yang-Mills Equations with Both Asymptotical Freedom and Confining Features

  曾定方

  理论物理通讯. 2013, 60(04): 465-470.

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  It is well known that confinings and asymptotic freedom are properties of quantum chromo-dynamics (QCD). But hints of these features can also be observed at purely classic levels. For this purpose we need to find solutions to the colorly-sourceful Yang-Mills equations with both confining and asymptotic freedom features. We provide such a solution in this paper which at the near-source region is of serial form, while at the far-away region is approximately expressed through simple elementary functions. From the solution, we derive out a classically non-perturbative beta function describing the running of effective coupling constant, which is linear in the couplings both in the infrared and ultraviolet region.
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  Holographic p-Wave Superconductors in Quintessence AdS Black Hole Spacetime

  陈松柏, 潘启沅

  理论物理通讯. 2013, 60(04): 471-478.

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  We construct a holographic p-wave superconductor model in the background of quintessence AdS black hole with an SU(2) Yang-Mills gauge field and then probe the effects of quintessence on the holographic p-wave superconductor. We investigate the relation between the critical temperature and the state parameter of quintessence, and present the numerical results for electric conductivity. It is shown that the condensation of the vector field becomes harder as the absolute value of the state parameter increases. Unlike the scalar condensate in the s-wave model, the condensation of the vector field in p-wave model can occur in the total value range of the state parameter w_q of quintessence. These results could help us know more about holographic superconductor and dark energy.
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  A New Determination of the Lambda-Nucleon Coupling Constants in Relativistic Mean Field Theory

  王小素, 桑红毅, 王家慧

  理论物理通讯. 2013, 60(04): 479-484.

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  A new determination of the Lambda-nucleon coupling constants in relativistic mean field theory is presented by optimizing both hyperon binding energy and spin-orbit splitting. Hypernuclear single particle spectra with the new coupling constants suggest the good agreement between the calculation and available data. The spin-orbit splitting of hyperon in medium mass hypernuclei is systematically larger than that in light- or heavy-mass hypernuclei. The sensitivity of the Lambda spin-orbit splitting to the omega-Lambda-Lambda tensor coupling term is also explored.
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  A New Lattice Model of Two-Lane Traffic Flow with the Consideration of the Honk Effect

  彭光含

  理论物理通讯. 2013, 60(04): 485-490.

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  In this paper, a new lattice model of two-lane traffic flow with the honk effect term is proposed to study the influence of the honk effect on wide moving jams under lane changing. The linear stability condition on two-lane highway is obtained by applying the linear stability theory. The modified Korteweg-de Vries (KdV) equation near the critical point is derived and the coexisting curves resulted from the modified KdV equation can be described, which shows that the critical point, the coexisting curve and the neutral stability line decrease with increasing the honk effect coefficient. A wide moving jam can be conceivably described approximately in the unstable region. Numerical simulation is performed to verify the analytic results. The results show that the honk effect could suppress effectively the congested traffic patterns about wide moving jam propagation in lattice model of two-lane traffic flow.
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  Effective Parameters on Energy Losses of Fast Electron in Fusion Mediums

  M. Mahdavi, S. F. Ghazizadeh

  理论物理通讯. 2013, 60(04): 491-495.

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  The stopping and scattering of fast electrons in a dense plasma relevant to inertial confinement fusion (ICF) are investigated numerically with the latest improved cross section equations. Binary and collective effects are considered to determine beam transport parameters such as range, penetration depth, spreading processes as straggling and blooming versus electron energy and plasma parameters. Blooming and straggling effects, which act as consequences of scattering with statistical assumption in collisions, lead to a non-uniform, extended region of energy deposition. Finally the mean angle of deflections is calculated for different plasma energies.
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  The Effect of Queueing Strategy on Network Traffic

  张学军, 管祥民, 孙登峰, 唐绍婷

  理论物理通讯. 2013, 60(04): 496-502.

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  In recent years, the transportation system has been faced by increasing challenge in congestion and inefficiency, and research in traffic network has become a significant area of interest. In this paper, we introduce a dynamic-information-based (DIB) queueing strategy into network traffic model under the efficient routing strategy. DIB makes a packet with higher priority to be delivered if there are less packets travelling along its path from the current node to the destination. It is found that, compared with the traditional first-in-first-out (FIFO) queueing strategy, DIB can effectively balance the traffic load of the system via delaying packets to be delivered to congested nodes. Although the network capacity has no obvious changes, some other indexes which reflect transportation efficiency are efficiently improved in the congestion state. Besides, extensive simulation results and discussions are provided to explain the phenomena. The results may provide novel insights for research on traffic systems.
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  Nonequilibrium Shot Noise Spectrum Through a Quantum Dot in the Kondo Regime: A Master Equation Approach under Self-Consistent Born Approximation

  刘玉, 金锦双, 栗军, 李新奇

  理论物理通讯. 2013, 60(04): 503-509.

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  We construct a number(n)-resolved master equation (ME) approach under self-consistent Born approximation (SCBA) for noise spectrum calculation. The formulation is essentially non-Markovian and incorporates properly the interlay of the multi-tunneling processes and many-body correlations. We apply this approach to the challenging nonequilibrium Kondo system and predict a profound nonequilibrium Kondo signature in the shot noise spectrum. The proposed n-SCBA-ME scheme goes completely beyond the scope of the Born-Markovian master equation approach, in the sense of being applicable to the shot noise of transport under small bias voltage, in non-Markovian regime, and with strong Coulomb correlations as favorably demonstrated in the nonequilibrium Kondo system.
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  Influence of Noise on Stability of the Ecosystem

  刘同波, 唐军

  理论物理通讯. 2013, 60(04): 510-514.

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  Based on a simplified predator-prey model, the influence of noise on the ecosystem has been studied. The results show the following facts. (i) For all parameter values, the existence of noise maintains the oscillatory state of the ecosystem, and enough strong noise can destroy the ecosystem, which means the annihilation of the species. (ii) Comparing to oscillation with small amplitude, while the ecosystem oscillates explosively with large amplitude, it is more likely to lose balance. In addition, the small-amplitude oscillation takes on higher level of regularity. All the numerical results are reasonable comparing to the general knowledge about ecosystem.
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  Molecular Mechanism of the Early Stage of Amyloidogenic Hexapeptides (NFGAIL) Aggregation

  施碧云, 周波, 蔡卓伟, 修鹏

  理论物理通讯. 2013, 60(04): 515-520.

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  Peptides/proteins aggregation can give rise to pathological conditions of many human diseases. Small partially ordered oligomers formed in the early stage of aggregation, rather than mature fibrils, are thought to be the main toxicity agent for the living cell. Thus, understanding the pathway and the underlying physical mechanism in the early stage of aggregation is very important for prevention and treatment of these protein functional diseases. Herein we use all-atom molecular dynamics simulations to study the aggregation of four NFGAIL hexapeptides (NFGAIL peptide is a core segment of human islet amyloid polypeptide and exhibits similar aggregation kinetics as the full-length polypeptide). We observe that the peptide monomers in water mainly adopt non-structural coil configurations; the four peptides which are randomly placed in water aggregate spontaneously to partially ordered oligomer (β-sheets) through dimerization or trimerization, with the dimerization predominated. Both parallel and anti-parallel β-sheets are observed. The hydrophobic interactions drive the initial peptides associations, and the subsequent conformational fluctuations promote the formation of more hydrogen bonds between the dangling hydrogen sites in the main chains of peptides.