Modern Physics Letters B

A model of phase transition of the first kind is introduced, based on the assumption that a classical gas of particles condenses in composite particles made up of various numbers of gas molecules. The transition temperature and the latent heat are derived, and the phase diagram is characterized.

The possibility of high-field Josephson magnetic resonance (HFJMR) in high-T_c superconductors (HTSCs) is theoretically demonstrated. The HFJMR is caused by the penetration of Abrikosov vortices into the grains in fields within H_c1≤H<H_x (where H_c1 is the first critical field and H_x is the field corresponding to vortex separation from pinning centers in the grains). The signals from microwave absorption is dependent on the ratio of grain sizes that produces junction, the anisotropy and the intergrain coupling strength. These properties can be used for investigations of HTSC macrostructures and a vortex matter.

We study a 2-qubit spin model for the possibility of realizing an arbitrary geometric quantum phase gate in terms of a single coherent magnetic pulse with multi-harmonic frequency. Using resonant transition approximation, the time-dependent Hamiltonian of two coupled spins can be solved analytically. The time evolution of the wave function is obtained without adiabatic approximation. The parameters of magnetic pulse, such as the frequency, amplitude, phase of each harmonic part as well as the time duration of the pulse are determined for achieving an arbitrary non-adiabatic geometric phase gate. The requirement of materials for realizing such a gate is analyzed. As a result, the non-adiabatic geometric controlled phase gates and A–A phase are also addressed.

We propose a feasible scheme for teleporting an unknown atomic state by using non-maximally entangled states in cavity QED. The distinct advantage of the scheme is that, not only can the teleportation and distillation procedure be realized simultaneously, but the scheme is also insensitive to the cavity decay and thermal field with the assistance of a strong classical driving field. In addition, the joint Bell-state measurement can be distinguished via detecting the atomic state.

Networks, acting as infrastructure for information communication, play an important role in modern society, therefore, the elements affecting the efficiency of network traffic are worthy of deep research. In this paper, we investigate numerically the problem of traffic congestion in complex networks through the use of various routing strategies. Three types of complex networks structures, namely Poisson random networks, small-world networks and scale-free networks, are considered. Three different routing strategies are used on networks: deterministic routing strategy, preferential routing strategy and shortest path routing strategy. We evaluate the efficiency of different routing strategies on different network topologies and show how the network structures and routing strategies influence the traffic congestion status.

The kinetics of the Ostwald ripening in a homogeneous supersaturated solution is studied both numerically and analytically. The time evolution of the grain-size distribution function in a new phase is theoretically described, taking into account the finite value of the maximal size of a grain. Two situations are considered: the kinetics of grain growth is controlled either by the grain-monomer reaction process (an early stage) or by the monomer diffusion process (a late stage). A transition to the final distribution is shown to take place through an intermediate-asymptotical mode of the Ostwald ripening kinetics, the crossover of the kinetic indices is demonstrated, and the duration of intermediate stage is evaluated.

Three samples of boro-germanate glass system (GeO₂–B₂O₃) were prepared by cooling the melt from 1473°K in the compositional series containing 40, 35 and 30 mol% B₂O₃. For these glasses the optical absorbance, % transmission, optical band gap, relative permittivity (ε_r), index of refraction (n) and index of dispersion (Abbe No., V_d) have been determined. The position of the absorption edge and hence the optical band gap (E_opt) was found to depend on glass composition. The absorption edge was attributed to indirect transitions. The values of E_opt and n_d were observed to decrease with increasing B₂O₃ content while ε_r and V_d increased with increasing B₂O₃ content.