International Journal of Modern Physics B

The dynamics of a general two qubit system in a noninetrial frame is investigated analytically, where it is assumed that both of its subsystems are differently accelerated. Two classes of initial traveling states are considered: self-transposed and generic pure states. The entanglement contained in all possible generated entangled states between the qubits and their anti-qubits is quantified. The usefulness of the traveling states as quantum channels to perform quantum teleportation is investigated. For the self-transposed classes, it is shown that the generalized Werner state is the most robust class and starting from a class of pure state, one can generate entangled states more robust than self-transposed classes.

Canonical-dissipative nonequilibrium energy distributions play an important role in the life sciences. In one of the most fundamental forms, such energy distributions correspond to two-parametric normal distributions truncated to the left. We present an implicit moment method involving the first and second energy moments to estimate the distribution parameters. It is shown that the method is consistent with Cohen's 1949 formula. The implementation of the algorithm is discussed and the range of admissible parameter values is identified. In addition, an application to an earlier study on human oscillatory hand movements is presented. In this earlier study, energy was conceptualized as the energy of a Hamiltonian oscillator model. The canonical-dissipative approach allows for studying the systematic change of the model parameters with oscillation frequency. It is shown that the results obtained with the implicit moment method are consistent with those derived in the earlier study by other means.

In this paper, we study the effect of external periodic pulses on spiral dynamics. Resonant entrainment bands were observed on the period T-axis, and T is close to rational multiples of the path curvature period of the spiral tip on the bands. It is also shown that spiral waves are drifted and eliminated by applying the driving method with suitable control parameters, and we reveal the mechanism which forces the spiral wave to periodically shift and rotate. In the domain near the spiral tip, the bidirectional wave excitations are periodically generated by external pulses, and each excitation induces a straight drift of the spiral wave tip. Numerical results show that the parameter range of the external pulse period T, used to successfully eliminate spiral waves, is broaden by appropriately increasing the values of the pulse width and the amplitude. The low-amplitude control scheme is operable in many real systems, and its study is beneficial to understand the forced spiral dynamics.

The amorphous Ni–Nb–Zr–H glassy alloy containing subnanometer-sized icosahedral Zr₅ Nb₅Ni₃ clusters exhibited four types of electronic phenomena: a metal/insulator transition, an electric current-induced voltage oscillation (Coulomb oscillation), giant capacitor behavior and an electron avalanche with superior resistivity. These findings could be excluded by charge density waves that the low-dimensional component of clusters, in which the atoms are lined up in chains along the [130] direction, plays important roles in various electron transport phenomena.

The critical-charge criterion of the stem-leader transition and the shielding effects of space charges on the streamer inception are two most contested issues on the inception of positive upward leader–streamer system (LSS). In this paper, a series of simulation experiments on the LSS inception were designed and carried out. A new critical-charge criterion in the range of 0.2–0.3 μC was proposed, and the previous criterion of 1.0 μC was proved to be harsh. The shielding effect of positive space charges on the streamer inception was verified directly by the experiment results. A theoretical formula for calculating the LSS inception voltage by the first-corona inception voltage was obtained. An appropriate first-corona inception time for getting an earlier LSS inception was proved to be existent. At last, the effects of the so-called improved lightning rods, such as the early streamer emission rod (ESE) and the controllable lightning rod (CL), were discussed, and it seemed that they would not help to extend the protective zones of the lightning rods.

As a suitable recombination process, recombination via tail state in organic bulk-heterojunction solar cells (OBHJs) is capable of reproducing both dark and illuminated current–voltage curves. The characteristic parameters of OBHJs based on recombination via tail are governed by transportation and extraction efficiency, and both processes are strongly dependent on the charge carrier mobility. Using a macroscopic simulation, we calculate the mobility dependent power conversion efficiency, open-circuit voltage, short-circuit current and fill factor. The open-circuit voltage is determined by not only carrier density n(p), but also by carrier density gradient. Furthermore, open-circuit voltage is more affected by majority charge carriers and less affected by minority ones.

We report a study of crystallographic parameters of the Sr₂CoNbO₆ double perovskite obtained from Rietveld analysis of X-ray diffraction data and electronic properties predictions using the density functional theory (DFT). The Sr₂CoNbO₆ material was prepared by the citrate precursor method. Diffraction analysis reveal that this material crystallizes in a structure which is tetragonal with lattice parameters a = 5.5960(3) Å and c = 7.9881(1) Å (space group I4/m). The density of states of Sr₂CoNbO₆ tetragonal distorted structure was calculated using DFT within the generalized gradient approximation. Results predict the semiconductor characteristics of this material which is majority due to the 3d-Co orbital with a energy gap of 0.2 eV. Structural lattice parameters obtained from the Rietveld refinement present a matching of 97% with that obtained from the Structure Prediction Diagnostic Software and 98% with the theoretical DFT results. Measurements of magnetization as a function of temperature evidence the occurrence of a magnetic ordering transition at T = 220 K and a marked irreversibility with a blocking temperature of 250 K for applied fields up to 100 Oe, which disappears for higher fields. Electronic paramagnetic resonance experiments evidence that the valence Co³⁺ is the most possible in the synthesized material.

FeCo/PZT/FeCo cylindrical heterostructures were prepared by electroless deposition. Scanning electron microscopy shows that the magnetostrictive FeCo layers are in contact with piezoelectric PZT directly. To control the resonant frequency at which the magnetoelectric coupling shows an obvious improvement, the height of cylinder needs to be taken into consideration. In the present work, three hollow cylinders with different height were polarized along the radial direction. It was shown that with the increase of cylinder height the magnetoelectric coefficient increased. Both experimental and calculated results show that the resonant frequency of FeCo/PZT/FeCo cylindrical layered composites decreases with increasing the cylinder height. Proper resonant frequency and strong ME effect could be obtained by optimizing the configuration.