Apr 2015, Volume 10 Issue 2

Cover illustration

  • Bismuth-based skutterudite is a new topological insulator, in which the bands involved in the topological band-inversion process are d- and p-orbitals, which is distinctive with usual topological insulators, for instance in Bi2Se3 and BiTeI the bands involved in the topological band-inversion process are only p-orbitals. The present of large d-electronic states (primarily the eg states) makes the electronic interaction in this topolog [Detail] ...

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    Guan-Xing Guo, Lei Zhang, Yong Zhang

    Because of the many potential medical applications of nanoparticles, considerable research has been conducted on the interactions between nanoparticles and biomembranes. We employed coarsegrained molecular dynamics simulations to study the infiltration of lipid-wrapping C60 and polyhydroxylated single-walled nanotubes. Diffusion coefficients and scaling factors are adopted to quantify the diffusivity of the biomembranes, and the rupture tension is used to measure the lateral strength of the lipid bilayer. According to our simulations, all wrapped nanoparticles, except those wrapped by dipalmitoyl-glycero-phosphoglycerol, can be inserted into the bilayers. Our simulations also reveal that the bilayers remain in free diffusion after the nanoparticle insertions while their diffusion coefficient can be altered significantly. The polyhydroxylated single-walled nanotubes lead to significant changes to the lateral strength of biomembranes and this effect depends on the quantity of the inserted nanoparticles. The simulations demonstrate the feasibility of using these methods to deliver nanoparticles while some suggestions are given for choosing the appropriate lipids for wrapping. The results also suggest that the functionalized nanoparticles could be applied in strengthening or weakening the lateral strength of biomembranes for specific purposes.

    Ming Yang, Xiao-Long Zhang, Wu-Ming Liu

    We review our theoretical advances in tunable topological quantum states in three- and twodimensional materials with strong spin–orbital couplings. In three-dimensional systems, we propose a new tunable topological insulator, bismuth-based skutterudites in which topological insulating states can be induced by external strains. The orbitals involved in the topological band-inversion process are the d- and p-orbitals, unlike typical topological insulators such as Bi2Se3and BiTeI, where only the p-orbitals are involved in the band-inversion process. Owing to the presence of large d-electronic states, the electronic interaction in our proposed topological insulator is much stronger than that in other conventional topological insulators. In two-dimensional systems, we investigated 3d-transition-metal-doped silicene. Using both an analytical model and first-principles Wannier interpolation, we demonstrate that silicene decorated with certain 3d transition metals such as vanadium can sustain a stable quantum anomalous Hall effect. We also predict that the quantum valley Hall effect and electrically tunable topological states could be realized in certain transition-metal-doped silicenes where the energy band inversion occurs. These findings provide realistic materials in which topological states could be arbitrarily controlled.

    Xiu Jun-Shan(修俊山), Bai Xue-Shi(白雪石), Vincent Motto-Ros, Yu Jin(俞进)

    Optical emissions from the major and trace elements embodied in a transparent gel prepared from cooking oil were detected after the gel was spread in a thin film on a metallic substrate. Such emissions are due to the indirect breakdown of the coating layer. The generated plasma, a mixture of substances from the substrate, the layer, and the ambient gas, was characterized using emission spectroscopy. The characteristics of the plasma formed on the metal with and without the coating layer were investigated. The results showed that Al emission induced from the aluminum substrates coated with oil films extends away from the target surface to ablate the oil film. This finally formed a bifurcating circulation of aluminum vapor against a spherical confinement wall in the front of the plume, which differed from the evolution of the plasma induced from the uncoated aluminum target. The strongest emissions of elements from the oil films can be observed at 2 mm above the target after a detection delay of 1.0 μs. A high temperature zone has been observed in the plasma after the delay of 1.0 μs for the plasma induced from the coated metal. This higher temperature determined in the plasma allows the consideration of the sensitive detection of trace elements in liquids, gels, biological samples, or thin films.

    Arash Ahmadivand, Saeed Golmohammadi

    In this study, gold nanodisk clusters in heptamer orientations as clusters were used to design a super-heptamer consisting of one central and six peripheral heptamers. We examined the position and movement of the plasmon and Fano resonances by sketching the spectral response of the superstructure for various nanodisk dimensions. The quality of the interference between the superradiant and subradiant plasmon resonance modes of the nanodisk clusters was found to depend strongly on the structural configuration and the refractive index of the environmental medium. We replaced the central heptamer with a nanodisk and probed the position of the Fano resonance by geometrically altering the nanodisk structure. Finally, the effect of the dielectric environment on the plasmon response of both of the studied structures was examined numerically and theoretically. The localized surface plasmon resonance sensitivity of the finite plasmonic structures to the presence of liquid substances was investigated and shown by plotting the linear figure of merit. The finite-difference time-domain method was used as a numerical tool to investigate the plasmon response of the structure.

    Jin-Hong Huang, Hong-Ji Li, Xiang-Yu Zhang, Yong-Yao Li

    We study the interactions of moving discrete solitons in waveguide arrays with two types of point defects that are constructed by varying either the local linear coupling or local waveguide propagation constant at the center of the waveguide array. A broad discrete soliton is kicked toward the defect and interacts with it. Transmission, reflection, scattering, and trapping during the interaction between the soliton and the defect occur depending on the parameters. The detailed behavior of the soliton dynamics is analyzed numerically. A transmission window in the parameter domain is found and the behavior of this window for different parameters is studied. The dynamics of the soliton in the transmission window is found to have chaotic features under certain circumstances and the causes of these phenomena are identified and discussed.

    Dong-Sheng Guo, Chao Yu, Jingtao Zhang, Ju Gao, Zhi-Wei Sun, Zhenrong Sun

    The currently well accepted cutoff law for laser induced high harmonic spectra predicts the cutoff energy as a linear combination of two interaction energies, the ponderomotive energy Up and the atomic biding energy Ip, with coefficients 3.17 and 1.32, respectively. Even though, this law has been there for twenty years or so, the background information for these two constants, such as how they relate to fundamental physics and mathematics constants, is still unknown. This simple fact, keeps this cutoff law remaining as an empirical one. Based on the cutoff property of Bessel functions and the Einstein photoelectric law in the multiphoton case, we show these two coefficients are algebraic constants, 9 - 42≈ 3.34 and 22- 1 ≈ 1.83, respectively. A recent spectra calculation and an experimental measurement support the new cutoff law.

    Stephen Lars Olsen

    QCD-motivated models for hadrons predict an assortment of “exotic” hadrons that have structures that are more complex than the quark-antiquark mesons and three-quark baryons of the original quark-parton model. These include pentaquark baryons, the six-quark H-dibaryon, and tetraquark, hybrid and glueball mesons. Despite extensive experimental searches, no unambiguous candidates for any of these exotic configurations have been identified. On the other hand, a number of meson states, one that seems to be a proton-antiproton bound state, and others that contain either charmed-anticharmed quark pairs or bottom-antibottom quark pairs, have been recently discovered that neither fit into the quark-antiquark meson picture nor match the expected properties of the QCD-inspired exotics. Here I briefly review results from a recent search for the H-dibaryon, and discuss some properties of the newly discovered states –the proton-antiproton state and the so-called XYZ mesons– and compare them with expectations for conventional quark-antiquark mesons and the predicted QCD-exotic states.

    Zi-Liang Li, Ding Lu, Bai-Song Xie

    By solving the quantum Vlasov equation, the dynamically assisted pair production for scalar quantum electrodynamics (QED) is investigated. It is verified that this mechanism still holds true for boson pair production. Two combinations of two electric fields having different time scales under various time delays are considered; it is found that the oscillations of the momentum spectrum and the number density of created bosons decrease with increasing time delay, and the latter has a maximum value when the time delay equals zero. Furthermore, the differences in vacuum pair production between bosons and fermions are also studied, and they are helpful for distinguishing the created bosons from fermions.

    Chun Li, Fei Long, Dong-Cheng Mei

    The effects of correlation between additive and multiplicative noises on the symmetry of an asymmetric bistable system are investigated. The steady-state probability distribution function of the system was calculated by using analytical and numerical methods. Results indicate that i) for the case of positive correlation between noises, as the correlation strength between additive and multiplicative noises, λ, increases, the symmetry of the system is restored; ii) for the case of negative correlation between noises, as the absolute value of λ increases, the symmetry of the system is destroyed; and iii) the analytic prediction agrees well with the stochastic simulation result.

    Qiao Bi

    A formalism of quantum computing with 2000 qubits or more in decoherence-free subspaces is presented. The subspace is triangular with respect to the index related to the environment. The quantum states in the subspaces are projected states ruled by a subdynamic kinetic equation. These projected states can be used to perform general, large-scale decoherence-free quantum computing.

    Ji Sai(季赛), Wang Fang(王芳), Liu Wen-Jie(刘文杰), Yuan Xiao-Min(袁晓敏)

    Recently, Li et al. presented a two-party quantum private comparison scheme using Greenberger–Horne–Zeilinger (GHZ) states and error-correcting code (ECC) [Int. J. Theor. Phys. 52, 2818 (2013)], claiming it is fault-tolerant and could be performed in a non-ideal scenario. However, there exists a fatal loophole in their private comparison scheme under a special attack, namely the twice-Hadamard-CNOT attack. Specifically, a malicious party may intercept the other party’s particles and execute Hadamard operations on the intercepted particles as well as on his or her own particles. Then, the malicious party could sequentially perform a controlled-NOT (CNOT) operation between intercepted particles and the auxiliary particles, as well as between his or her own particles and the auxiliary particles prepared in advance. By measuring the auxiliary particles, the secret input will be revealed to the malicious party without being detected. For resisting this special attack, a feasible improved scheme is proposed by introducing a permutation operator before the third party (TP) sends the particle sequences to each participant.

    Hong-Yi Fan,Jun-Hua Chen,Peng-Fei Zhang

    We propose an entangled fractional squeezing transformation (EFrST) generated by using two mutually conjugate entangled state representations with the following operator: e-iα(a1?a2?+a1a2)eiπa2?a2; this transformation sharply contrasts the complex fractional Fourier transformation produced by using e-iα(a1?a2?+a2?a2)eiπa2?a2 (see Front. Phys. DOI 10.1007/s11467-014-0445-x). The EFrST is obtained by converting the triangular functions in the integration kernel of the usual fractional Fourier transformation into hyperbolic functions, i.e., tanα → tanhα and sinα → sinhα. The fractional property of the EFrST can be well described by virtue of the properties of the entangled state representations.