2014年, 第61卷, 第03期　
刊出日期：2014-03-01

  

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  Characterizing Quantum Correlations in Arbitrary-Dimensional Bipartite Systems Using Hurwitz’s Theory

  李辉, 李岩松, 王书浩, 龙桂鲁

  理论物理通讯. 2014, 61(03): 273-280.

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  Quantum correlations play vital roles in the quantum features in quantum information processing tasks. Among the measures of quantum correlations, quantum discord (QD) and entanglement of formation (EOF) are two significant ones. Recent research has shown that there exists a relation between QD and EOF, which makes QD more significant in quantum information theory. However, until now, there exists no general method of characterizing quantum discord in high-dimensional quantum systems. In this paper, we have proposed a general method for calculating quantum discord in arbitrary-dimensional bipartite quantum systems in terms of Hurwitz's theory. Applications including the Werner state, the spin-1 XXZ model thermal equilibrium state, the Horodecki state, and the separable-bound-free entanglement state are investigated. We present the method of obtaining the EOF of arbitrary-dimensional bipartite quantum states via purification, and the relationship between QD and EOF.
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  Non-Maximal Tripartite Entanglement Degradation of Dirac and Scalar Fields in Non-Inertial Frames

  Salman Khan, Niaz Ali Khan, M.K. Khan

  理论物理通讯. 2014, 61(03): 281-288.

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  The π-tangle is used to study the behavior of entanglement of a nonmaximal tripartite state of both Dirac and scalar fields in accelerated frame. For Dirac fields, the degree of degradation with acceleration of both one-tangle of accelerated observer and π-tangle, for the same initial entanglement, is different by just interchanging the values of probability amplitudes. A fraction of both one-tangles and the π-tangle always survives for any choice of acceleration and the degree of initial entanglement. For scalar field, the one-tangle of accelerated observer depends on the choice of values of probability amplitudes and it vanishes in the range of infinite acceleration, whereas for π-tangle this is not always true. The dependence of π-tangle on probability amplitudes varies with acceleration. In the lower range of acceleration, its behavior changes by switching between the values of probability amplitudes and for larger values of acceleration this dependence on probability amplitudes vanishes. Interestingly, unlike bipartite entanglement, the degradation of π-tangle against acceleration in the case of scalar fields is slower than for Dirac fields.
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  One Hair Postulate for Hawking Radiation as Tunneling Process

  董辉, 蔡庆宇, 刘旭峰, 孙昌璞

  理论物理通讯. 2014, 61(03): 289-292.

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  For Hawking radiation, treated as a tunneling process, the no-hair theorem of black hole together with the law of energy conservation is utilized to postulate that the tunneling rate only depends on the external qualities (e.g., the mass for the Schwarzschild black hole) and the energy of the radiated particle. This postulate is justified by the WKB approximation for calculating the tunneling probability. Based on this postulate, a general formula for the tunneling probability is derived without referring to the concrete form of black hole metric. This formula implies an intrinsic correlation between the successive processes of the black hole radiation of two or more particles. It also suggests a kind of entropy conservation and thus resolves the puzzle of black hole information loss in some sense.
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  Uncertainty and Certainty Relations for Pauli Observables in Terms of Rényi Entropies of Order α∈(0;1]

  Alexey E. Rastegin

  理论物理通讯. 2014, 61(03): 293-298.

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  We obtain uncertainty and certainty relations of state-independent form for the three Pauli observables with use of the Rényi entropies of order α∈(0;1]. It is shown that these entropic bounds are tight in the sense that they are always reached with certain pure states. A new result is the condition for equality in Rényi-entropy uncertainty relations for the Pauli observables. Upper entropic bounds in the pure-state case are also novel. Combining the presented bounds leads to a band, in which the rescaled average Rényi α-entropy ranges for a pure measured state. A width of this band is compared with the Tsallis formulation derived previously.
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  Effect of Phase Shift in Dual-Rail Perfect State Transfer

  王兆明, 张忠军, 顾永建

  理论物理通讯. 2014, 61(03): 299-304.

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  We investigate the effect of phase shift on the perfect state transfer through two parallel one-dimensional ring-shaped spin chains. We find that the total success probability can be significantly enhanced by phase shift control when the communication channel consists of two odd chains. The average time to gain unit success probability is discussed, showing that a proper phase shift can be used to enhance the efficiency of state transmission.
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  Two Schemes for Probabilistic Remote Preparation of a Four-Particle Entangled Cluster-Type State

  侯奎, 王洪燕, 李义宝

  理论物理通讯. 2014, 61(03): 305-314.

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  Using partial entangled states as the quantum channel, two schemes for probabilistic remote preparation of the four-particle cluster-type state with real and complex coefficients are presented. In the first scheme, the sender and the receiver share two partial Bell states and one partial three-qubit GHZ stats as the quantum channel, and the sender can help a remote receiver to prepare a four-particle entangled cluster-type state by using three-qubit projective measurements with certain probability. In the second scheme, the quantum channel is composed of two partial three-qubit GHZ states, the remote state preparation (RSP) can be successfully realized via the positive operator valued measure (POVM), and the two-particle projective measurements are also needed in this process. The total success probability and classical communication cost are calculated.
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  Controlled Remote Preparing of an Arbitrary 2-Qudit State with Two-Particle Entanglements and Positive Operator-Valued Measure

  廖月明, 周萍, 覃星辰, 何燕和, 覃健生

  理论物理通讯. 2014, 61(03): 315-321.

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  We present a scheme for symmetric controlled remote preparation of an arbitrary 2-qudit state form a sender to either of the two receivers via positive operator-valued measurement and pure entangled two-particle states. The first sender transforms the quantum channel shared by all the agents via POVM according to her knowledge of prepared state. All the senders perform single- or two-particle projective measurements on their entangled particles and the receiver can probabilisticaly reconstruct the original state on her entangled particles via unitary transformation and auxiliary qubit. The scheme is optimal as the probability which the receiver prepares the original state equals to the entanglement of the quantum channel. Moreover, it is more convenience in application than others as it requires only two-particle entanglements for preparing an arbitrary two-qudit state.
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  Hyperconcentration Based on Projection Measurements

  陈晓, 曾志, 李熙涵

  理论物理通讯. 2014, 61(03): 322-328.

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  We propose an efficient hyperconcentration protocol for distilling maximally hyperentangled state from partially entangled pure state, resorting to the projection measurement on an auxiliary photon. In our scheme, two photons simultaneously entangled in polarization states and spatial modes are considered. One party performs quantum nondemolition detections on his photon and an additional photon to produce three photon hyperentangled state, then he projects the assistant photon into an orthogonal basis composed of both the polarization and spatial degree of freedom. Then the state of the left two photons collapses into maximally hyperentangled state with a certain probability. In the rest cases, some less-entangled states are obtained, which can be used as resource for the next round concentration. By repeating the concentration process for several rounds, a higher success probability can be obtained, which makes our scheme useful in practical quantum information applications.
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  Synchronization of Phase Oscillators in Networks with Certain Frequency Sequence

  冯媛媛, 吴亮, 朱士群

  理论物理通讯. 2014, 61(03): 329-333.

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  Synchronization of Kuramoto phase oscillators arranged in real complex neural networks is investigated. It is shown that the synchronization greatly depends on the sets of natural frequencies of the involved oscillators. The influence of network connectivity heterogeneity on synchronization depends particularly on the correlation between natural frequencies and node degrees. This finding implies a potential application that inhibiting the effects caused by the changes of network structure can be balanced out nicely by choosing the correlation parameter appropriately.
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  Bright Solitons on Continuous Wave Background in Blood Vessels

  项佳杰, 蒋华杰, 戴朝卿, 王悦悦

  理论物理通讯. 2014, 61(03): 334-338.

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  The nonlinear Schrödinger equation (NLSE) with variable coefficients in blood vessels is discussed via an NLSE-based constructive method, and exact solutions are obtained including multi-soliton solutions with and without continuous wave backgrounds. The dynamical behaviors of these soliton solutions are studied. The solitonic propagation behaviors such as restraint and sustainment on continuous wave background are discussed by altering the value of dispersion parameter δ. Moreover, the longitude controllable behaviors are also reported by modulating the dispersion parameter δ. These results are potentially useful for future experiments in various blood vessels.
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  Wronskian Form Solutions for a Variable Coefficient Kadomtsev-Petviashvili Equation

  吕卓生, 任文秀

  理论物理通讯. 2014, 61(03): 339-343.

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  Starting from a simple transformation, and with the aid of symbolic computation, we establish the relationship between the solution of a generalized variable coefficient Kadomtsev-Petviashvili (vKP) equation and the solution of a system of linear partial differential equations. According to this relation, we obtain Wronskian form solutions of the vKP equation, and further present N-soliton-like solutions for some degenerated forms of the vKP equation. Moreover, we also discuss the influences of arbitrary constants on the soliton and N-soliton solutions of the KPII equation.
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  Efficiency at Maximum Power Output of a Quantum-Mechanical Brayton Cycle

  袁媛, 何济洲, 高勇, 王建辉

  理论物理通讯. 2014, 61(03): 344-348.

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  The performance in finite time of a quantum-mechanical Brayton engine cycle is discussed, without introduction of temperature. The engine model consists of two quantum isoenergetic and two quantum isobaric processes, and works with a single particle in a harmonic trap. Directly employing the finite-time thermodynamics, the efficiency at maximum power output is determined. Extending the harmonic trap to a power-law trap, we find that the efficiency at maximum power is independent of any parameter involved in the model, but depends on the confinement of the trapping potential.
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  Quantum Discord in Two-Qubit System Constructed from the Yang-Baxter Equation

  苟立丹, 王晓茜, 徐玉梅, 孙媛媛

  理论物理通讯. 2014, 61(03): 349-353.

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  Quantum correlations among parts of a composite quantum system are a fundamental resource for several applications in quantum information. In general, quantum discord can measure quantum correlations. In that way, we investigate the quantum discord of the two-qubit system constructed from the Yang-Baxter Equation. The density matrix of this system is generated through the unitary Yang-Baxter matrix ?. The analytical expression and numerical result of quantum discord and geometric measure of quantum discord are obtained for the Yang-Baxter system. These results show that quantum discord and geometric measure of quantum discord are only connect with the parameter θ, which is the important spectral parameter in Yang-Baxter equation.
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  Production of Charged Heavy Quarkonium-Like States at the LHC and Tevatron

  郭奉坤, Ulf-G. Meißner, 王伟

  理论物理通讯. 2014, 61(03): 354-358.

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  We study prompt hadroproduction of the charged bottomonium-like states Z_b^± (10610) and Z_b^± (10650), and the charged charmonium-like states Z_c^± (3900) and Z_c^± (4020), at the Tevatron and the LHC, provided that these states are S-wave hadronic molecules. Using two Monte Carlo event generators, Herwig and Pythia, to simulate the production of heavy meson pairs, we derive an order-of-magnitude estimate of the production rates for these four particles. Our estimates yield a cross section at the nb level for the Z_b(10610) and Z_b(10650). The results for the Z_c(3900) and Z_c(4020) are larger by a factor of 20-30. These cross sections are large enough to be observed, and measurements at hadron colliders in the future will supplement the study using electron-positron collisions, and therefore allow to explore the mysterious nature of these exotic states.
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  Calculation of the Mass of X(3872) by the Mandelstam Generalization of the Gell-Mann-Low Method

  周华彬, 吕晓夫

  理论物理通讯. 2014, 61(03): 359-364.

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  On the basis of assuming that the narrow state X(3872) is a molecule state consisting of D⁰ and D^*0, we apply the Mandelstam generalization of the Gell-Mann-Low method to calculate the matrix element of quark current between the heavy meson states described by Bether-Salpeter wave function. In calculation of the matrix element of quark current the operator product expansion is used in order to include the nonperturbative contribution of the vacuum condensates. In this scheme we calculate the mass of X(3872). We believe that this scheme is closer to QCD than the previous work.
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  The Fifth Order Peregrine Breather and Its Eight-Parameter Deformations Solutions of the NLS Equation

  Pierre Gaillard

  理论物理通讯. 2014, 61(03): 365-369.

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  We construct here explicitly new deformations of the Peregrine breather of order 5 with 8 real parameters. This gives new families of quasi-rational solutions of the NLS equation and thus one can describe in a more precise way the phenomena of appearance of multi rogue waves. With this method, we construct new patterns of different types of rogue waves. We get at the same time, the triangular configurations as well as rings isolated. Moreover, one sees appearing for certain values of the parameters, new configurations of concentric rings.
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  Studying Validity of Single-Fluid Model in Inertial Confinement Fusion

  谷建法, 范征锋, 戴振生, 叶文华, 裴文兵, 朱少平

  理论物理通讯. 2014, 61(03): 370-376.

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  The validity of single-fluid model in inertial confinement fusion simulations is studied by comparing the results of the multi- and single-fluid models. The multi-fluid model includes the effects of collision and interpenetration between fluid species. By simulating the collision of fluid species, steady-state shock propagation into the thin DT gas and expansion of hohlraum Au wall heated by lasers, the results show that the validity of single-fluid model is strongly dependent on the ratio of the characteristic length of the simulated system to the particle mean free path. When the characteristic length L is one order larger than the mean free path λ, the single-fluid model's results are found to be in good agreement with the multi-fluid model's simulations, and the modeling of single-fluid remains valid. If the value of L/λ is lower than 10, the interpenetration between fluid species is significant, and the single-fluid simulations show some unphysical results; while the multi-fluid model can describe well the interpenetration and mix phenomena, and give more reasonable results.
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  Large Amplitude Dust Ion Acoustic Solitons and Double Layers in Dusty Plasmas with Ion Streaming and High-Energy Tail Electron Distribution

  Mehran Shahmansouri, Mouloud Tribeche

  理论物理通讯. 2014, 61(03): 377-384.

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  Large amplitude dust ion acoustic (DIA) solitons as well as double layers (DLs) are studied in a dusty plasma having a high-energy-tail electron distribution. The influence of electron deviation from the Maxwellian distribution and ion streaming on the existence domain of solitons is discussed in the (M,f) space using the pseudo-potential approach. It is found that in the presence of streaming ions and for a fixed f, solitons may appear for larger values of M. This means that in the presence of ion streaming, high values of the Mach number are needed to have soliton. The DIA solitary waves profile is highly sensitive to the ion streaming speed. Their amplitude is found to decrease with an increase of the ion streaming speed. In addition, we find that the ion streaming effect may lead to the appearance of double layers. The results of this article should be useful in understanding the basic nonlinear features of DIA waves propagating in space dusty plasmas, especially those including a relative motion between species, such as comet tails and solar wind streams, etc.
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  Manipulation of Persistent Spin Helix States by Weak External Magnetic Fields

  胡茂金, 柴政, 胡梁宾

  理论物理通讯. 2014, 61(03): 385-390.

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  We study theoretically the effect of weak external magnetic fields on persistent spin helix states in semiconductor two-dimensional electron gases with both Rashba and linear-in-momentum Dresselhaus spin-orbit coupling. We show that in the presence of weak external magnetic fields, some basic properties of a persistent spin helix state, including the dispersion relation between the decay time and the magnitude of the wavevector, the maximum decay time and the value of the characteristic magnitude of the wavevector at which the maximum decay time occurs, will all depend sensitively on the directions of applied external magnetic fields.
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  Simulation of Electronic Total-Reflection Effect in a Graphene Junction

  陶伟伟, 刘波, 戴乾, 汪萨克

  理论物理通讯. 2014, 61(03): 391-396.

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  We investigate theoretically the electron-reflection phenomenon in a graphene n⁺n junction based on electron optics, where the local potential in the left n⁺ region is higher than that in the right n region. It is demonstrated numerically that electrons emitting from a point source in the n⁺ region will experience total internal reflection through the interface of the junction. The reflection becomes stronger and the transmission becomes weaker with decrease of the local potential in the right graphene ribbon. It is also found that when a nonideal interface is considered in the junction, the electron-reflection effect is enhanced due to interfacial backscattering.
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  D-term Chaotic Braneworld in Supergravity Constrained by WMAP9 Data

  A. Safsafi, M. Ferricha-Alami, H. Chakir, J. Inchaouh, M. Bennai

  理论物理通讯. 2014, 61(03): 397-402.

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  We study a supergravity D-term chaotic inflationary model, in the context of the braneworld scenario, in particular we consider the Randall-Sundrum model type 2. Using the latest release from the combination of WMAP9, eCMB, BAO, and H₀, we show that the inflation observables depend only on the number of e-folds N. We also derive all known spectrum inflationary parameters, which are widely consistent with WMAP9 data for a particular choice of values N specially for the scalar spectral index n_s and the ratio r. However, the running of the scalar spectral index dn_s/dlnk is now excluded from the range given by the latest observational measurements.