2016年, 第65卷, 第03期　
刊出日期：2016-03-01

  

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  Double Wronskian Solution and Soliton Properties of the Nonisospectral BKP Equation

  王灯山, 李祥贵, 陈昌麒, 周健

  理论物理通讯. 2016, 65(03): 259-265.

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  Based on the Wronskian technique and Lax pair, double Wronskian solution of the nonisospectral BKP equation is presented explicitly. The speed and dynamical influence of the one soliton are discussed. Soliton resonances of two soliton are shown by means of density distributions. Soliton properties are also investigated in the inhomogeneous media.
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  Dynamics of Information Entropies of Atom-Field Entangled States Generated via the Jaynes-Cummings Model

  R. Pakniat, M. K. Tavassoly, M. H. Zandi

  理论物理通讯. 2016, 65(03): 266-272.

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  In this paper we have studied the dynamical evolution of Shannon information entropies in position and momentum spaces for two classes of (nonstationary) atom-field entangled states, which are obtained via the Jaynes-Cummings model and its generalization. We have focused on the interaction between two- and Ξ-type three-level atoms with the single-mode quantized field. The three-dimensional plots of entropy densities in position and momentum spaces are presented versus corresponding coordinates and time, numerically. It is observed that for particular values of the parameters of the systems, the entropy squeezing in position space occurs. Finally, we have shown that the well-known BBM (Beckner, Bialynicki-Birola and Mycielsky) inequality, which is a stronger statement of the Heisenberg uncertainty relation, is properly satisfied.
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  Temporal Behavior of Rabi Oscillation in Nanomechanical QED System with a Nonlinear Resonator

  肖骁, 赵明月, 于书敏, 高一波

  理论物理通讯. 2016, 65(03): 273-277.

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  In nanomechanical QED system, consisting of a charge qubit and a nanomechanical resonator with intrinsic nonlinearity, we study the temporal behavior of Rabi oscillation in the nonlinear Jaynes-Cummings model. Using microscopic master equation approach, we solve time evolution of the density operator describing this model. Also, the probability of excited state of charge qubit is calculated. These analytic calculations show how nonlinearity parameter and decay rates of two different excited states of the qubit-resonator system affect time-oscillating and decaying of Rabi oscillation.
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  Dynamics of Entanglement in Qubit-Qutrit with x-Component of DM Interaction

  Kapil K. Sharma, S. N. Pandey

  理论物理通讯. 2016, 65(03): 278-284.

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  In this present paper we study the entanglement dynamics in qubit A-qutrit B pair under x component of Dzyaloshinshkii-Moriya interaction (D_x) by taking an auxiliary qubit C. Here, we consider an entangled qubit-qutrit pair initially prepared in two parameter qubit-qutrit states and one auxiliary qubit prepared in pure state interacts with the qutrit of the pair through DM interaction. We trace away the auxiliary qubit and calculate the reduced dynamics in qubit A-qutrit B pair to study the influence of the state of auxiliary qubit C and D_x on entanglement. We find that the state (probability amplitude) of auxiliary qubit does not influence the entanglement, only D_x influences the same. The phenomenon of entanglement sudden death (ESD) induced by D_x has also been observed. We also present the affected and unaffected two parameter qubit-qutrit states by D_x.
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  Quantum Measurement of Two-Qubit System in Damping Noise Environment

  杨青, 刘慧, 甄秀兰, 杨名, 曹卓良

  理论物理通讯. 2016, 65(03): 285-291.

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  It is known that the inevitable interaction of the entangled qubits with their environments may result in the degradation of quantum correlation. We study the decoherence of two remote qubits under general local single- and two-sided amplitude-damping channel (ADC). By using concurrence, quantum discord and Clauser-Horne-Shimony-Holt (CHSH) inequality, we find that the relation between the residual quantum correlations and the initial ones are different. Recently, Wang et al.[Int. J. Theor. Phys. 54 (2015) 5] showed that there exist a set of partially entangled states that are more robust than maximally entangled states in terms of the residual quantum correlation measured by concurrence, fully entangled fraction and quantum discord, respectively. Here we find that both in single- and two-sided ADC, only the evolution of CHSH inequality with the initial parameter is proportional to that of the initial nonlocality. That means the initial state with maximally nonlocality will retain its role in the evolution. It implies that the evolution of nonlocality may reveal the characteristics of quantum state better. Furthermore, we discuss the evolutions of the three different quantum measurements with the initial parameter under generalized amplitude damping channel (GADC) and find that they are all proportional to that of the initial state.
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  Resonances of Spin-1/2 Fermions in Eddington-Inspired Born-Infeld Gravity

  付启明, 赵力, 杜云芝, 古宝珉

  理论物理通讯. 2016, 65(03): 292-300.

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  We investigate the fermionic resonances for both chiralities in five-dimensional Eddington-inspired Born-Infeld (EiBI) theory. In order to localize fermion on the brane, it needs to be considered the Yukawa coupling between the fermion and the background scalar field. In our models, since the background scalar field has kink, double kink, or anti-kink solution, the system has rich resonant Kaluza-Klein (KK) modes structure. The massive KK fermionic modes feel a volcano potential, which result in a fermionic zero mode and a set of continuous massive KK modes. The inner structure of the branes and a free parameter in background scalar field influence the resonant behaviors of the massive KK fermions.
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  Plane Symmetric Solutions in f(R, T) Gravity

  M. Farasat Shamir

  理论物理通讯. 2016, 65(03): 301-307.

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  The main purpose of this paper is to investigate the exact solutions of plane symmetric spacetime in the context of f(R,T) gravity[Phys. Rev. D 84 (2011) 024020], where f(R,T) is an arbitrary function of Ricci scalar R and trace of the energy momentum tensor T. We explore the exact solutions for two different classes of f(R,T) models. The first class f(R,T)=R+2f(T) yields a solution which corresponds to Taub's metric while the second class f(R,T)=f₁(R)+f₂(T) provides two additional solutions which include the well known anti-deSitter spacetime. The energy densities and corresponding functions for f(R,T) models are evaluated in each case.
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  Inflation in Non-de Sitter Background with Coherent States

  E. Yusofi, M. Mohsenzadeh, M. R. Tanhayi

  理论物理通讯. 2016, 65(03): 308-314.

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  We use the excited coherent states built over the initial non-de Sitter modes, to study the modification of spectra of primordial scalar fluctuation. Non-de Sitter modes are actually the asymptotic solution of the inflaton field equation[J. High Energy Phys. 09 (2014) 020]. We build excited coherent states over the non-de Sitter modes and despite the lack of interactions in the Lagrangian, we find a non-zero one-point function. It is shown that the primordial non-Gaussianity resulting from excited-de Sitter modes depend both of time and background space-time. It is very tiny of order (≤ 10^-24), at the Planck initial fixed time that confirmed by resent observations for single field inflation but it grows in the present epoch. Moreover, our results at the leading order are similar to what obtained with general initial states and in the dS limit leads to standard results[J. Cosmol. Astropart. Phys. 1202 (2012) 005]. We will show that the non-dS modes and its resulting spectrum are more usable for far past time limit.
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  Conformal Killing Vectors in LRS Bianchi Type V Spacetimes

  Suhail Khan, Tahir Hussain, Ashfaque H. Bokhari, Gulzar Ali Khan

  理论物理通讯. 2016, 65(03): 315-320.

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  In this note, we investigate conformal Killing vectors (CKVs) of locally rotationally symmetric (LRS) Bianchi type V spacetimes. Subject to some integrability conditions, CKVs up to implicit functions of (t,x) are obtained. Solving these integrability conditions in some particular cases, the CKVs are completely determined, obtaining a classification of LRS Bianchi type V spacetimes. The inheriting conformal Killing vectors of LRS Bianchi type V spacetimes are also discussed.
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  A Note on the Equivalence of Post-Newtonian Lagrangian and Hamiltonian Formulations

  陈荣超, 伍歆

  理论物理通讯. 2016, 65(03): 321-328.

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  Recently, it has been generally claimed that a low order post-Newtonian (PN) Lagrangian formulation, whose Euler-Lagrange equations are up to an infinite PN order, can be identical to a PN Hamiltonian formulation at the infinite order from a theoretical point of view. In general, this result is difficult to check because the detailed expressions of the Euler-Lagrange equations and the equivalent Hamiltonian at the infinite order are clearly unknown. However, there is no difficulty in some cases. In fact, this claim is shown analytically by means of a special first-order post-Newtonian (1PN) Lagrangian formulation of relativistic circular restricted three-body problem, where both the Euler-Lagrange equations and the equivalent Hamiltonian are not only expanded to all PN orders, but have converged functions. It is also shown numerically that both the Euler-Lagrange equations of the low order Lagrangian and the Hamiltonian are equivalent only at high enough finite orders.
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  Collapse of Self-Interacting Scalar Field in Anti-de Sitter Space

  蔡荣根, 季力伟, 杨润秋

  理论物理通讯. 2016, 65(03): 329-334.

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  The gravitational collapse of a massless scalar field with a self-interaction term λφ⁴ in anti-de Sitter space is investigated. We numerically investigate the effect of the self-interaction term on the critical amplitudes, forming time of apparent horizon, stable island, and energy transformation. The results show that a positive λ suppresses the formation of black hole, while a negative λ enhances the process. We define two susceptibilities to characterize the effect of the self-interaction on the black hole formation, and find that near the critical amplitude, there exists a universal scaling relation with the critical exponent α≈0.74 for the time of black hole formation.
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  On Generating Discrete Integrable Systems via Lie Algebras and Commutator Equations

  张玉峰, Honwah Tam

  理论物理通讯. 2016, 65(03): 335-340.

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  In the paper, we introduce the Lie algebras and the commutator equations to rewrite the Tu-d scheme for generating discrete integrable systems regularly. By the approach the various loop algebras of the Lie algebra A₁ are defined so that the well-known Toda hierarchy and a novel discrete integrable system are obtained, respectively. A reduction of the later hierarchy is just right the famous Ablowitz-Ladik hierarchy. Finally, via two different enlarging Lie algebras of the Lie algebra A₁, we derive two resulting differential-difference integrable couplings of the Toda hierarchy, of course, they are all various discrete expanding integrable models of the Toda hierarchy. When the introduced spectral matrices are higher degrees, the way presented in the paper is more convenient to generate discrete integrable equations than the Tu-d scheme by using the software Maple.
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  Nonlocal Symmetries and Interaction Solutions for Potential Kadomtsev-Petviashvili Equation

  任博, 俞军, 刘希忠

  理论物理通讯. 2016, 65(03): 341-346.

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  The nonlocal symmetry for the potential Kadomtsev-Petviashvili (pKP) equation is derived by the truncated Painlevé analysis. The nonlocal symmetry is localized to the Lie point symmetry by introducing the auxiliary dependent variable. Thanks to localization process, the finite symmetry transformations related with the nonlocal symmetry are obtained by solving the prolonged systems. The inelastic interactions among the multiple-front waves of the pKP equation are generated from the finite symmetry transformations. Based on the consistent tanh expansion method, a nonauto-Bäcklund transformation (BT) theorem of the pKP equation is constructed. We can get many new types of interaction solutions because of the existence of an arbitrary function in the nonauto-BT theorem. Some special interaction solutions are investigated both in analytical and graphical ways.
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  Electronic Structure of Helium Atom in a Quantum Dot

  Jayanta K. Saha, S. Bhattacharyya, T. K. Mukherjee

  理论物理通讯. 2016, 65(03): 347-353.

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  Bound and resonance states of helium atom have been investigated inside a quantum dot by using explicitly correlated Hylleraas type basis set within the framework of stabilization method. To be specific, precise energy eigenvalues of bound 1sns (¹S^e) (n=1-6) states and the resonance parameters i.e. positions and widths of ¹S^e states due to 2sns (n=2-5) and 2pnp (n=2-5) configurations of confined helium below N=2 ionization threshold of He⁺ have been estimated. The two-parameter (Depth and Width) finite oscillator potential is used to represent the confining potential due to the quantum dot. It has been explicitly demonstrated that the electronic structural properties become sensitive functions of the dot size. It is observed from the calculations of ionization potential that the stability of an impurity ion within a quantum dot may be manipulated by varying the confinement parameters. A possibility of controlling the autoionization lifetime of doubly excited states of two-electron ions by tuning the width of the quantum cavity is also discussed here.
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  Re-examining Photodetachment of H^- near a Spherical Surface using Closed-Orbit Theory

  尤晓鹏, 杜孟利

  理论物理通讯. 2016, 65(03): 354-360.

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  Photodeachment of H^- near a reflective spherical surface was studied by Haneef et al.[J. Phys. B:At. Mol. Opt. Phys. 44 (2011) 195004] using a theoretical imaging method. The total cross section displays interesting oscillations. Here we re-examine the total photodetachment cross section of this system by directly applying the standard closed-orbit theory. Our result for the total cross section differs from the result obtained by Haneef et al. The difference between the two results vanishes in the limit of large radius of the reflective sphere. We argue that the theoretical imaging method developed originally for photodetachment near a flat surface can not be directly applied to the present system.
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  Statistical Law of High-Energy Fullerene and Its Derivatives Passing Through Graphene

  徐志成, 温家乐, 钟伟荣, 魏亮

  理论物理通讯. 2016, 65(03): 361-365.

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  The behavior of graphene bombarded by fullerene (C60 and C70) and its derivatives through using non-equilibrium molecular dynamics method are studied. The microscopic mechanism of passing through graphene is obviously related to the initial structure of destroying carbon-carbon bonds and the strong interaction between the circular region of graphene and the cluster. The probability of passing through graphene depends on the incident velocity of clusters, the species of clusters, the temperature of heat baths, and the defect of graphene. Our results can provide a perspective for further understanding the mechanism of generating nanopores in graphene. The clusters used here may also bring about some potential utilities in the functionalization of graphene and the production of nanopores.
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  Extracting Structure Parameters of Dimers for Molecular Tunneling Ionization Model

  赵松峰, 黄方, 王国利, 周效信

  理论物理通讯. 2016, 65(03): 366-374.

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  We determine structure parameters of the highest occupied molecular orbital (HOMO) of 27 dimers for the molecular tunneling ionization (so called MO-ADK) model of Tong et al.[Phys. Rev. A 66 (2002) 033402]. The molecular wave functions with correct asymptotic behavior are obtained by solving the time-in}dependent Schrödinger equation with B-spline functions and molecular potentials which are numerically created using the density functional theory. We examine the alignment-dependent tunneling ionization probabilities from MO-ADK model for several molecules by comparing with the molecular strong-field approximation (MO-SFA) calculations. We show the molecular Perelomov-Popov-Terent'ev (MO-PPT) can successfully give the laser wavelength dependence of ionization rates (or probabilities). Based on the MO-PPT model, two diatomic molecules having valence orbital with antibonding systems (i.e., Cl₂, Ne₂) show strong ionization suppression when compared with their corresponding closest companion atoms.
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  Thermal Magnifier and Minifier

  沈翔瀛, 陈祎璇, 黄吉平

  理论物理通讯. 2016, 65(03): 375-380.

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  For thermal conduction cases, one can detect the size of an object explicitly by measuring the temperature distribution around it. If the temperature is the only signature we can obtain, we will give an incorrect judgment on the shape or size of the object by disturbing the distribution of it. According to this principle, in this article, we develop a transformation method and design a dual-functional thermal device, which can create a thermal illusion that the object inside it "seems" to appear bigger or smaller than its original size. This device can functionally switch among magnifier and minifier at will. The proposed device consists of two layers:the cloak and the complementary material. A thermal cloak can make the internal region thermally "invisible" while the complementary layer offsets this effect. The combination leads to the illusion of magnification and minification. As a result of finite element simulations, the performances of the illusions are confirmed.
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  An Improved Discrete-Time Model for Heterogeneous High-Speed Train Traffic Flow

  许琰, 贾斌, 李明华, 李新刚

  理论物理通讯. 2016, 65(03): 381-392.

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  This paper aims to present a simulation model for heterogeneous high-speed train traffic flow based on an improved discrete-time model (IDTM). In the proposed simulation model, four train control strategies, including departing strategy, traveling strategy, braking strategy, overtaking strategy, are well defined to optimize train movements. Based on the proposed simulation model, some characteristics of train traffic flow are investigated. Numerical results indicate that the departure time intervals, the station dwell time, the section length, and the ratio of fast trains have different influence on traffic capacity and train average velocity. The results can provide some theoretical support for the strategy making of railway departments.