Modern Physics Letters B

An optical scheme of the quantum teleportation of superposed coherent states from light pulse to the atoms in Bose–Einstein condensate in terms of optical elements is presented. Beam splitters, photodetectors, cross-Kerr medium, and coherent state sources are needed in this scheme. The probability of successful teleportation is also obtained.

ZnO:V thin films with different doping concentration (0%, 1.8%, 3.9%, 6.8%, 10%, and 13%) were fabricated by direct current magnetron sputtering. The X-ray diffraction patterns show that the wurzite structure changed with doping concentration. Furthermore, we could not find any vanadium cluster or phase separation in the X-ray diffraction patterns. The photoluminescence of ZnO:V with different vanadium concentration was investigated. The room temperature photoluminescence spectrum indicates that the films have purple band with 370 nm and the bands with 475 and 490 nm. The peak intensity of room temperature photoluminescence spectrum was affected by vanadium contents and its position remained stable. The intensity of band with 370 nm increases with raising the vanadium concentration and then decreases. The hysteresis behavior indicates that films were ferromagnetic at 50 K. Room temperature ferromagnetism was observed for the film with the doping concentration at 6.8%. However, in this case almost no hysteresis is noticeable. The results implied that the doping concentration and crystalline microstructure influence strongly the film's magnetic characteristics. Increasing the vanadium content in the film caused the degradation of the magnetic ordering.

We have investigated the electronic and magnetic properties of GaC_1-xMn₃ (x = 0, 0.125, 0.25) using first-principles density functional theory within the generalized gradient approximation (GGA) + U schemes. The crystal structures of the compounds are cubic for x = 0, 0.125, 0.25. The lattice parameters and unit cell volume decrease as the C vacancy increase. Our spin polarized calculations give metallic ground state for x = 0, 0.125, 0.25. The magnetic structure for x = 0, 0.125 are antiferromagnetic, while for x = 0.25 it is ferromagnetic. From the density of states (DOS), the hybridization between the C 2p and Mn 3d state is the main reason for magnetic transition.

A novel thermal tuning technique of fiber Bragg gratings is proposed. With this technique, the thermal sensitivity of FBG can now be flexibly designed. The proposed technique is used in an erbium-doped fiber ring laser. A wavelength shift of 6.8 nm is obtained with a temperature change of only 20°C, which corresponds to a thermal sensitivity of 0.34 nm/°C. The 3 dB linewidth of the laser is less than 0.1 nm in the whole tuning range. The threshold and slope efficiency of the laser are 7.9 mW and 18.6%, respectively. The laser tuning has good linearity and good repeatability.

The non-magnetic impurities influence on the magnetic properties of a single layer thin film treated in the Heisenberg model with three different interactions is investigated, using Monte Carlo technique. Low different impurities concentration levels are discussed (the impurities being randomly distributed in the magnetic spins lattice). The relative magnetization, the magnetic susceptibility and the specific heat are investigated in order to detect the potential magnetic phase transitions in the Ising region of the phase diagram of the system presented above. In this context, the dependency of the critical temperature that characterizes the ferromagnetism-disordered phase (FM–PM) transition as a function of the impurity concentration level is studied. Finally, the lattice size effect is taken into account and a quantitative study about the relative variation of the critical parameters is performed.

In this paper, we present a method for synchronizing two different chaotic systems that have unknown parameters that are affected by stochastic variations generated by the Wiener process. The parameters are expressed by the sum of their mean values and the white Gaussian noise multiplied by the diffusion matrices. To describe the unknown nonlinear function yielded by Itô's lemma due to the unknown diffusion matrices, a fuzzy logic system is employed. Using adaptive fuzzy control, the response system is synchronized with the drive system within an arbitrarily small error bound. Numerical simulations show the effectiveness of the proposed method.

In this paper, the schemes of quantum key distribution and remote state preparation of an arbitrary two-qubit state via four-particle cluster state are proposed. The efficiency of the former is 1 and the probability of the latter is 1(1/4) if the coefficients are real (complex).

Based on an exactly-solvable spin-boson model, the geometric phase (GP) of a system of two qubits collectively coupled to a quantum bath is investigated. In this scenario, the decomposition of GP into the sum of GP of the subsystem should be forbidden. We demonstrate that the environment-induced modifications of the GP usually include not only the pure decoherence effect, but also the information about the environment evolution. We also show the dependence of the GP upon the entangled initial state and extend it to the case of multi-qubits system.

The exact traveling wave solutions of (4 + 1)-dimensional nonlinear Fokas equation is obtained by using three distinct methods with symbolic computation. The modified tanh–coth method is implemented to obtain single soliton solutions whereas the extended Jacobi elliptic function method is applied to derive doubly periodic wave solutions for this higher-dimensional integrable equation. The Exp-function method gives generalized wave solutions with some free parameters. It is shown that soliton solutions and triangular solutions can be established as the limits of the Jacobi doubly periodic wave solutions.

Applicable in fluid dynamics and plasmas, a generalized variable-coefficient Korteweg–de Vries (vcKdV) equation is investigated analytically employing the Hirota bilinear method in this paper. The bilinear form for such a model is derived through a dependent variable transformation. Based on the bilinear form, the integrable properties such as the N-solitonic solution, the Bäcklund transformation and the Lax pair for the vcKdV equation are obtained. Additionally, it is shown that the bilinear Bäcklund transformation can turn into the one denoted in the original variables.

By introducing suitable non-isospectral flows, we construct two sets of symmetries for the isospectral differential–difference Kadomstev–Petviashvili hierarchy. The symmetries form an infinite dimensional Lie algebra.