Modern Physics Letters B

The polar surface-optical (SO) phonon modes and their dispersion relations in a quantum box are derived within the dielectric continuum approximation. Then, having quantized the vibrational eigenmodes, we give the electron-SO phonon interaction Hamiltonian in a quantum box.

Based on the entangled state representation <η| in two-mode Fock space (Fan and Klauder, Phys. Rev.A49, 704 (1994)), we provide an alternative approach for analyzing quantum teleportation of continuous variables and go a step further by deriving some relations between input (target) states and teleported states. The natural representation of the two-mode squeezing operator in the |η> representation greatly simplifies our calculations.

The minimal entanglement fidelities of the phase damping channel, depolarizing channel, two-Pauli channel and amplitude damping channel are calculated. It is shown that for the same condition, the minimal fidelity of the phase damping channel is the biggest among the four channels. The minimal fidelity of the depolarizing channel is bigger than the other two.

The properties of pulse propagation in a nonlinear fiber including a linear damped term added in the nonlinear Schrödinger equation with cubic and quintic terms is analyzed analytically. We apply the variational modified approach based on the Lagrangian that describes the dynamic of a system and, with a suitable trial function, we obtain a solution which is as accurate as a pertubative solution found by inverse scattering transformation in earlier works. As a result, we show that the quintic term can retain the pulse propagation more stably and in a greater time in optical fiber.

We report a ferromagnetic resonance (FMR) study on the in-plane anisotropy of the patterned permalloy film with arrays of submicron rectangular elements prepared by electron beam lithography and the theoretical fitting of the FMR results, by which the in-plane anisotropy, effective magnetization, gyromagnetic ratio and g value of the samples are determined. The theoretical curves of the dependence of the resonance field on the field orientation Φ_H fit well with the experimental data.

Magnetic susceptibility and XPS results on xFe₂O₃ · (100-x) [4Bi₂O₃ · PbO] where 0<x ≤20 samples are presented in order to point out the oxidation states and the distribution of iron ions in the lead-bismuthate matrix. The valence state of iron ions changes from Fe³⁺ to Fe²⁺ as the Fe₂O₃ content increases from 1 to 20 mol%. The XPS data indicate the migration of metallic elements in the inner part of the bulk investigated samples.

EPR investigations on La_0.7Ca_0.3MnO₃ were carried out in the temperature range from 14 K to 300 K. The important observations are: (i) a coincidence of resistivity maxima with the disappearance of paramagnetic EPR line I, which suggests that there exists a strong electron–phonon interaction, (ii) the appearance of an "out of phase" line near the Curie temperature T_c due to the formation of spin clusters consisting of Mn³⁺ and Mn⁴⁺ ions, and (iii) the appearance of an intense EPR line III and the splitting of FC and ZFC magnetization curves below 160 K, ascribed to local magnetic frustrations. The above EPR observations provide experimental evidence for the co existence of spin fluctuations and magnetic disorders in this sample, which leads to the formation of spin-glass features below T_c.