2018年, 第70卷, 第03期　
刊出日期：2018-09-01

  

• 全选
  |

• Select
  Double Wronskian Solutions for a Generalized Nonautonomous Nonlinear Equation in a Nonlinear Inhomogeneous Fiber

  解西阳, 蒙高庆

  理论物理通讯. 2018, 70(03): 249-254.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  A generalized nonautonomous nonlinear equation, which describes the ultrashort optical pulse propagating in a nonlinear inhomogeneous fiber, is investigated. N-soliton solutions for such an equation are constructed and verified with the Wronskian technique. Collisions among the three solitons are discussed and illustrated, and effects of the coefficients σ₁(x, t), σ₂(x, t), σ₃(x, t) and v(x, t) on the collisions are graphically analyzed, where σ₁(x, t), σ₂(x, t), σ₃(x, t) and v(x, t) are the first-, second-, third-order dispersion parameters and an inhomogeneous parameter related to the phase modulation and gain(loss), respectively. The head-on collisions among the three solitons are observed, where the collisions are elastc. When σ₁(x, t) is chosen as the function of x, amplitudes of the solitons do not alter, but the speed of one of the solitons changes. σ₂(x, t) is found to affect the amplitudes and speeds of the two of the solitons. It reveals that the collision features of the solitons alter with σ₃(x, t)=-1.8x. Additionally, traveling directions of the three solitons are observed to be parallel when we change the value of v(x, t).
• Select
  Breathers and Rogue Waves Derived from an Extended Multi-dimensional N-Coupled Higher-Order Nonlinear Schrödinger Equation in Optical Communication Systems

  白成林, 蔡跃进, 罗清龙

  理论物理通讯. 2018, 70(03): 255-262.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  In this paper, an extended multi-dimensional N-coupled higher-order nonlinear Schrödinger equation (NCHNLSE), which can describe the propagation of the ultrashort pulses in wavelength division multiplexing (WDM) systems, is investigated. By the bilinear method, we construct the breather solutions for the extended (1+1), (2+1) and (3+1)-dimensional N-CHNLSE. The rogue waves are derived as a limiting form of breathers with the aid of symbolic computation. The effect of group velocity dispersion (GVD), third-order dispersion (TOD) and nonlinearity on breathers and rogue waves solutions are discussed in the optical communication systems.
• Select
  Symmetric Surface Momentum and Centripetal Force for a Particle on a Curved Surface

  M. S. Shikakhwa

  理论物理通讯. 2018, 70(03): 263-267.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The Hermitian surface momentum operator for a particle confined to a 2D curved surface spanned by orthogonal coordinates and embedded in 3D space is expressed as a symmetric expression in derivatives with respect to the surface coordinates and so is manifestly along the surface. This is an alternative form to the one reported in the literature and usually named geometric momentum, which has a term proportional to the mean curvature along the direction normal to the surface, and so "apparently" not along the surface. The symmetric form of the momentum is the sum of two symmetric Hermitian operators along the two orthogonal directions defined by the surface coordinates. The centripetal force operator for a particle on the surface of a cylinder and a sphere is calculated by taking the time derivative of the momentum and is seen to be a symmetrization of the well-known classical expressions.
• Select
  Effectiveness of Non-Markovian Methods for Quantum Discord Dynamics of Non-coupled Two-Qubit System

  黄勇刚, 王小云, 杨学弦, 邓科, 彭金璋, 赵鹤平

  理论物理通讯. 2018, 70(03): 268-272.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The dissipative dynamics of non-coupled two qubits interacting with independent reservoir is studied by solving the non-Markovian master equation. In order to examine the effectiveness of the Nakajima-Zwanzig and timeconvolutionless master equations in the description of quantum correlation dynamics, different coupled regimes are investigated. The comparison between the above two master equation methods for investigating the dynamics of quantum discord is also made. Finally, we further confirm that the two master equations should be applied in different regimes of qubits coupled to their reservoirs, respectively.
• Select
  Non-Markovian Master Equation for Distant Resonators Embedded in a One-Dimensional Waveguide

  陈歆宇, 张闻钊, 李崇

  理论物理通讯. 2018, 70(03): 273-279.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  We develop a master equation approach to describe the dynamics of distant resonators coupled through a one-dimensional waveguide. Our method takes into account the back-actions of the reservoirs, and enables us to calculate the exact dynamics of the complete system at all times. We show that such system can cause nonexponential and long-lived photon decay due to the existence of a relaxation effect. The physical origin of non-Markovianity in our model system is the finite propagation speed resulting in time delays in communication between the nodes, and strong decay rate of the emitters into the waveguide. When the distance satisfies the standing wave condition, we find that when the time delay is increased, the dark modes formation is no longer perfect, and the average photon number of dark mode decreases in steady time limit.
• Select
  Noether Symmetry and Conserved Quantities of Fractional Birkhoffian System in Terms of Herglotz Variational Problem

  田雪, 张毅

  理论物理通讯. 2018, 70(03): 280-288.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The aim of this paper is to study the Herglotz variational principle of the fractional Birkhoffian system and its Noether symmetry and conserved quantities. First, the fractional Pfaff-Herglotz action and the fractional PfaffHerglotz principle are presented. Second, based on different definitions of fractional derivatives, four kinds of fractional Birkhoff's equations in terms of the Herglotz variational principle are established. Further, the definition and criterion of Noether symmetry of the fractional Birkhoffian system in terms of the Herglotz variational problem are given. According to the relationship between the symmetry and the conserved quantities, the Noether's theorems within four different fractional derivatives are derived, which can reduce to the Noether's theorem of the Birkhoffian system in terms of the Herglotz variational principle under the classical conditions. As applications of the Noether's t heorems of the fractional Birkhoffian system in terms of the Herglotz variational principle, an example is given at the end of this paper.
• Select
  Inclusive Photoproduction of Υ(1s) and J/ψ in Ultra-peripheral p-Pb Collisions at √s=5.5 TeV

  江学敏, 李云德

  理论物理通讯. 2018, 70(03): 289-293.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  With a photon spectrum of high energy charged partons, both differential and total cross sections of J/ψ and Υ(1s) inclusive photoproduction in ultra-peripheral p-Pb Collisions (UPCs) at √s=5.5 TeV are given. A direct photon process and a resolved photon process including fragment and non-fragment contributions are considered. The total cross section is compared to the inelastic production results in coherent p-Pb collisions at the same center-of-mass energy. Our results seem non-negligible.
• Select
  Dirac Equation with a New Tensor Interaction under Spin and Pseudospin Symmetries

  C. A. Onate, M. C. Onyeaju, A. N. Ikot, O. Ebomwonyi, J. O. A. Idiodi

  理论物理通讯. 2018, 70(03): 294-298.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The approximate analytical solutions of the Dirac equation under spin and pseudospin symmetries are examined using a suitable approximation scheme in the framework of parametric Nikiforov-Uvarov method. Because a tensor interaction in the Dirac equation removes the energy degeneracy in the spin and pseudospin doublets that leads to atomic stability, we study the Dirac equation with a Hellmann-like tensor potential newly proposed in this study. The newly proposed tensor potential removes the degeneracy from both the spin symmetry and pseudospin symmetry completely. The proposed tensor potential seems better than the Coulomb and Yukawa-like tensor potentials.
• Select
  Self-consistency of a Modification Method Based on Membrane Model with Minimal Length Considered

  唐浩, 孙成一, 吴滨, 宋宇, 岳瑞宏

  理论物理通讯. 2018, 70(03): 299-302.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  By adopting a result from generalized uncertainty principles (GUP), we modify the inner bound of the membrane model to a physical fixed value and get the cut-offs naturally rather than by hand, which are both in brickwall model and membrane model, and the semi-classical quantization condition could always be valid as well. We also calculate the entropies of Schwarzschild-de Sitter black hole and find the GUP we choose qualitatively shows that the requirement of mass in this method is the same as the natural requirement of the Schwarzschild-de Sitter black hole, which means the method might be self-consistent.
• Select
  Universal Pseudo-PT-Antisymmetry on One-Dimensional Atomic Optical Lattices

  王欣, 孙昌璞

  理论物理通讯. 2018, 70(03): 303-310.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  We present the interesting result that under sinusoidal field detuning setting along the propagation direction of 1D atomic lattices, the probe susceptibility response of the lattices, regardless of atomic configuration, uniformly demonstrates pseudo-PT-antisymmetry, which by our definition corresponds to n(z)=-n^*(-z), the complex refractive index antisymmetry along propagation axis, and when being cast back to quantum mechanical side, corresponds to V (x, t)=-V^*(x, -t), the conjugate time-reversal antisymmetry of complex potential. We define this as the pseudo PT-antisymmetry, and prove the reason for this phenomenon to be the quantum-mechanical nature described by master equation under weak field approximation for any configuration of 1D atomic lattices. This work will help to deepen the understanding of origin of optical response features of atomic lattices, and will certainly open up the gate to a more rigorous, durable and flexible method of atomic optical lattice design.
• Select
  Pulse Slippage of Resonant Third Harmonic Generation in Electron-Hole Plasma

  Vishal Thakur, Prabhdeep Kaur, Amanpreet Kaur, Niti Kant

  理论物理通讯. 2018, 70(03): 311-316.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  Effect of pulse slippage on resonant third harmonic generation of a short pulse laser in electron-hole plasma in the presence of wiggler magnetic field has been investigated. The group velocity mismatch of the third harmonic pulse and the fundamental pulse is significant in electron hole plasma. As the third harmonic pulse has higher group velocity than that of fundamental pulse, therefore, it moves faster than the fundamental pulse. It gets slipped out of the domain of fundamental pulse and its amplitude saturates. Phase matching condition is satisfied by applying wiggler magnetic field, which provides additional angular momentum to the third harmonic photon to make the process resonant. Enhancement in the efficiency of third harmonic generation of an intense short pulse laser in electron-hole plasma embedded with a magnetic wiggler is seen.
• Select
  Quadruple Gaussian Laser Beam Profile Dynamics in Collisionless Magnetized Plasma

  Shivani Vij, Munish Aggarwal

  理论物理通讯. 2018, 70(03): 317-324.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  This paper presents an investigation of self-focusing of a quadruple Gaussian laser beam in collisionless magnetized plasma. The nonlinearity due to ponderomotive force which arises on account of nonuniform intensity distribution of the laser beam is considered. The nonlinear partial differential equation governing the evaluation of complex envelope in the slowly varying envelope approximation is solved using a paraxial formalism. The self-focusing mechanism in magnetized plasma, in the presence of self-compression mechanism will be analyzed in contrast to the case in which it is absent. It can be observed that, in case of ponderomotive nonlinearity, the self-compression mechanism obstructs the pulse self-focusing above a certain intensity value. The effect of an external magnetic field is to generate pulses with smaller spot size and shorter compression length. The lateral separation parameter and the initial intensity of the laser beam play a crucial role on focusing and compression parameters. Also, the three-dimensional analysis of pulse propagation is presented by coupling the self-focusing equation with the self-compression one.
• Select
  Cylindrical Three-Dimensional Dust-Ion Acoustic Propagation in Plasmas

  S. K. El-Labany, E. K. El-Shewy, H. N. Abd El-Razek, A. A. El-Rahman

  理论物理通讯. 2018, 70(03): 325-330.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  Wave properties of solitons in an unmagnetized four-component dusty plasma system contains isothermal distributed electrons, mobile ions, and negative-positive dusty grains have been examined. To study DIA wave properties, a reductive perturbation (RP) analysis is used. By a reductive perturbation (RP) analysis under convenient coordinate transformation, the three dimension Kadomtsev-Petviashvili equation in cylindrical coordinates is obtained. The effects of dust grain charge on soliton pulse structures are studied. More specifically, solitary profile depending on the axial, radial, and polar angle coordinates with time is discussed. This investigation may be viable in plasmas of the Earth's mesosphere.
• Select
  Improving the Performance of Practical Decoy-State Measurement-Device-Independent Quantum Key Distribution with Biased Basis Choice

  张春辉, 张春梅, 王琴

  理论物理通讯. 2018, 70(03): 331-336.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  Statistical fluctuations are unavoidable in realistic quantum key distribution (QKD) due to finite-size effect. Based on the four-intensity proposal on measurement-device-independent QKD (MDI-QKD) in[Phys. Rev. A 93 (2016) 042324], we particularly analyze the scenario that only three intensities are used, namely a three-intensity decoy-state MDI-QKD with biased basis choice. After performing full parameter optimization method, simulations results demonstrate that this scenario can obtain distinct enhancement compared with the conventional unbiased threeintensity decoy-state method, e.g. Xu et al.'s[Phys. Rev. A 89 (2014) 052333]. Furthermore, results also show that it works more efficiently by using HSPS than using WCS at longer transmission distance.
• Select
  Nano Fluid Flow Analysis in the Presence of Slip Effects and Wall Properties by Means of Contraction and Expansion

  Hina Sadaf, Rabia Malik

  理论物理通讯. 2018, 70(03): 337-343.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The present article is a study of mixed convective peristaltic flow of Cu-blood nanofluid confined in a non-uniform tube along with the velocity slip conditions and wall properties. Endoscopic or catheterized special effects are also taken into description. Upon utilization of the large wavelength and small reynolds number approximation, the non-dimensional governing differential equation took a more simplified form, which is then solved for the exact solutions. Afterwards, these outcomes are offered graphically and are debated in detail. Velocity profile for pure blood as well as Cu-blood and no-slip and slip effects are also discussed separately. Streamlines pattern is also discussed for different physical parameters.
• Select
  Third-Order Optical Nonlinearity in Two-Dimensional Transition Metal Dichalcogenides

  Sina Khorasani

  理论物理通讯. 2018, 70(03): 344-360.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  We present a detailed calculation of the linear and nonlinear optical response of four types of monolayer twodimensional (2D) transition-metal dichalcogenides (TMDCs), having the formula MX₂ with M=Mo, W and X=S, Se. The calculations are based on 6-band tight-binding model of TMDCs, and then performing a semi-classical perturbation analysis of response functions. We numerically calculate the linear χ_μν⁽¹⁾ (-ω;ω) and nonlinear surface susceptibility tensors χ_μνζη⁽³⁾(-ω_Σ; ω_r; ω_s; ω_t) with ω_Σ=ω_r+ω_s+ω_t. Both non-degenerate and degenerate cases are studied for thirdharmonic generation and nonlinear refractive index, respectively. Computational results obtained with no external fitting parameters are discussed regarding two recent reported experiments on MoS₂, and thus we can confirm the extraordinarily strong optical nonlinearity of TMDCs. As a possible application, we demonstrate generation of a π/4-rotated squeezed state by means of nonlinear response of TMDCs, in a silica micro-disk resonator covered with the 2D material. Our proposed method will enable accurate calculations of nonlinear optical response, such as four-wave mixing and highharmonic generation in 2D materials and their heterostructures, thus enabling study of novel functionalities of 2D photonic integrated circuits.
• Select
  Significance of Darcy-Forchheimer Porous Medium in Nanofluid Through Carbon Nanotubes

  Taseer Muhammad, Dian-Chen Lu, B. Mahanthesh, Mohamed R. Eid, Muhammad Ramzan, Amanullah Dar

  理论物理通讯. 2018, 70(03): 361-366.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  This article manages Darcy-Forchheimer 3D flow of water based carbon nanomaterial (CNTs). A bidirectional nonlinear stretchable surface has been utilized to make the flow. Disturbance in permeable space has been represented by Darcy Forchheimer (DF) expression. Heat transfer mechanism is explored through convective heating. Outcomes for SWCNT and MWCNT have been displayed and compared. The reduction of partial differential framework into nonlinear common differential framework is made through reasonable variables. Optimal series scheme is utilized for arrangements advancement of associated flow issue. Optimal homotopic solution expressions for velocities and temperature are studied through graphs by considering various estimations of physical variables. Moreover surface drag coefficients and heat transfer rate are analyzed through plots.
• Select
  Vertical Sediment Concentration Distribution in High-Concentrated Flows: An Analytical Solution Using Homotopy Analysis Method

  Manotosh Kumbhakar, Jitraj Saha, Koeli Ghoshal, Jitendra Kumar, Vijay P. Singh

  理论物理通讯. 2018, 70(03): 367-378.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  Transport of suspended sediment in open channel flow has an enormous impact on real life situations, viz. control and management of reservoir sedimentation, geomorphic evolution such as dunes, rivers, and coastlines etc. Transport entails advection and diffusion. Turbulent diffusion is governed by the concept of Fick's law, which is based on the molecular diffusion theory, and the equation that represents the distribution of sediment concentration is the advection-diffusion equation. The study uses the existing governing equation which considers different phases for solid and fluid, and then couples the two phases. To deal with high-concentrated flow, sediment and turbulent diffusion coefficients are taken to be different from each other. The effect of hindered settling on sediment particles is incorporated in the governing equation, which makes the equation highly non-linear. This study derives an explicit closed-form analytical solution to the generalized one-dimensional diffusion equation representing the vertical sediment concentration distribution with an arbitrary turbulent diffusion coefficient profile. The solution is obtained by Homotopy Analysis Method, which does not rely on the small parameters present in the equation. Finally, the solution is validated by comparing it with the implicit solution and the numerical solution. A relevant set of laboratory data is selected to check the applicability of the model, and a close agreement shows the potential of the model in the context of application to high-concentrated sediment-laden open channel flow.