Table of contents

In this paper, we propose a scheme to construct an entangled state between s cavities and a single two-level atom, each cavity in a coherent state. Also, we propose the use of this scheme to produce the entanglement swapping of atomic states. We use the atomic collision scheme present by Zheng and Guo (2000 Phys. Rev. Lett.85 2392).

General dispersion relation of plasma waves in a finite temperature flowing dusty plasma in the presence of an external magnetic field has been examined using the Vlasov– Maxwell system of equations. In the frequency regime between ion and dust cyclotron frequencies, the transverse electromagnetic dust-ion magnetosonic wave mode is found to propagate nearly perpendicular to the external magnetic field, which reduces to the usual magnetosonic wave in the absence of dust. The electrostatic dust-lower-hybrid mode is also recovered propagating nearly perpendicular to the external magnetic field in a finite ion temperature and cold dust plasma, which for the strong ion-Larmor radius effect reduces to the usual dust-acoustic wave driven by the ion pressure.

The critical properties of the magnetic spin-1/2 Ising film are studied using the effective field theory with a probability distribution technique that accounts for the self-spin correlation functions. We discuss an L-layer film of simple cubic symmetry with nearest-neighbour interactions in which the strength of the interaction at the surface is different from the bulk value. We derive the phase diagram, the longitudinal susceptibility and the effective critical exponents in the case of a perfect surface. In such films, the critical temperature can shift to either lower or higher temperature compared to the corresponding bulk value.

It is shown that the deviation of a fractional quantum Hall edge fluid from power-law correlation functions with universal exponent α=1/ν as observed in a recent experiment may be explained when studied in the framework of Berry's phase. At the edge, a nonlocal effect is induced in the construction of the electron creation operator in terms of the edge boson fields. This nonlocality is responsible for the deviation of the power-law exponent from α=1/ν of the edge fluid. The nonlocal effect is incorporated through a length scale which is maximal at the lowest Landau level (LLL). The length scale decreases at the higher LLs and we have mixing of LLs. This will cause edge reconstruction and the existence of a striped phase at ν=1 and 1/3 and will be robust at higher LLs. We have also shown that there are gapless edge excitations described by chiral boson fields and the number of branches of chiral boson fields can be related to the polarization states of electrons in the bulk.

The Adomian decomposition method (ADM) has been successively used to find the explicit and numerical solutions of the time fractional of a coupled nonlinear fractional equations. Four models of special interest with fractional time derivative of order α, 0<α<1 are considered and solved by means of ADM. The behaviour of Adomian solutions and the effects of different values of α are shown graphically. Numerical examples are tested to illustrate the pertinent feature of the proposed algorithm.

Lattices of face-centred cubic crystals (fcc), due to irradiation processes, may become disordered in stable configurations like the dumb-bell configuration (DBC) or body-centred interstitial (BCI). In this work, a quantum mechanical treatment for the calculation of transmission coefficients of channelled positrons from their bound states in the normal lattice regions into the allowed bound states in the disordered regions is given as a function of the length of the disordered regions. In order to obtain more reliable results, higher anharmonic terms in the planar channelling potential are considered in the calculations by using first-order perturbation theory where new bound states have been found. The calculations were executed in the energy range 10–200 MeV of the incident positron on a copper single crystal in the planar direction (100).

In this paper, we calculate the Wigner distribution function to reveal the quantum–classical connection for the Schrödinger equation with position-dependent effective mass. On mapping this wave equation into an isospectral one with constant mass, the Wigner distribution function, which can be used to calculate matrix elements and expectation values of operators, can be obtained analytically for a given mass distribution and potential function.

A new dispersion relation for electrostatic perturbations is derived by employing the hydrodynamic and Poisson equations for an unmagnetized, partially ionized, self-gravitating plasma whose constituents are positive–negative charged and neutral dust particles. Collisions caused by the dust-neutral and neutral-dust particulates are incorporated. Two new modes are found without collisional effects. The frequency spectra are numerically analysed to study the effects of Jeans frequencies due to positive, negative and neutral dust particulates and neutral temperature on the real angular frequencies and the growth rates.

Lower hybrid current drive (LHCD) experiments have been carried out to achieve high performance for long pulse operation in the Hefei tokamak-7 (HT-7) superconducting tokamak. Multifaceted asymmetric radiation from the edge (MARFE) phenomena and an improved confinement mode induced by a MARFE are observed in LHCD plasmas when P_LH>160 kW and the edge safety factor q(a) is slightly less than 6.5. It is found that an improved confinement mode induced by a MARFE, characterized by H_α line emissions drops and the line-averaged density increase is triggered in the MARFE discharges. The MARFE event occurs at t=1120 ms following the L–H transition, and the improved confinement phase exists for about 65 ms from t=1140 ms after the L–H transition. The LHCD plasma results basically are typical with MARFEs and it is an improved confinement mode; they are unique in that they appear at very low values in the HT -7 tokamak.

Some special Bäcklund transformation (BT) theorems and a particular nonlinear superposition theorem are established to find exact solutions for a non-integrable model, the (N+1)-dimensional ϕ⁴ scalar field. Some new types of exact solutions such as the conoid periodic–periodic interaction waves and the periodic–solitary wave interaction solutions are explicitly given. The interaction solutions possess abundant structures, thanks to the intrusion of some arbitrary functions in the expressions of the special solutions.

Riemann derived two equations for unsteady isentropic one-dimensional fluid flow which by means of a transformation can be conflated into a single equation. We perform a symmetry analysis of this equation and find that the number of Lie point symmetries is not what one would expect for an hyperbolic equation. We use some of the symmetries to construct basis solutions and the others as creation operators to generate further solutions. Included in the solutions we obtain are polynomial solutions which remind one of the heat polynomials found as solutions of the classical heat equation.

Using the molecular template method, we synthesized a nanoporous SiO₂ thin film with ultra-low dielectric constant (k). Fourier transform infrared spectroscopy and differential thermal analysis were carried out to investigate the effect of n-hexane washing on the film properties before and after the surface modification process. The results showed the important role of the washing process, and revealed that –CH₃bonds substituted for –OH bonds in the films modified by trimethylchlorosilane (TMCS)/n-hexane solution, which avoided the destruction of the network structure of the thin films. The nanometre pore size (10–20 nm), good network structure and thickness of SiO₂ films were observed by scanning electron microscopy (SEM). The effects of the post-treatment conditions on the dielectric constant (1.5) and the porosity (78%) of the films were also investigated.

We have investigated the stability of the lower hybrid wave in a plasma containing hydrogen and positively and negatively charged oxygen ions. The electrons, streaming parallel to the magnetic field, can excite the instability provided their drift velocity exceeds the parallel phase velocity of the wave. This is true for both the collisionless and collisional cases. The growth/damping rate is modified by a factor dependent directly on the number densities and square of the charges on the oxygen ions and inversely on the masses of these ions. Thus oxygen ions, irrespective of the nature of the charge on them, tend to stabilize the wave; the higher the degree of ionization of the oxygen ions, the greater the stabilization for a given number density.

Plasma wave excitation by beating two lasers in a plasma is inhibited by the presence of clusters. The clusters undergo Coulomb explosion under the combined fields of the two lasers. The cluster susceptibility thus acquires a temporal variation. As the lasers exert ponderomotive forces on plasma electrons and cluster electrons and drive a plasma wave at the beat frequency of the two lasers, the time evolution of cluster susceptibility detunes the plasma resonance limiting the amplitude of the plasma wave.

We consider a highly excited atom in a good cavity strongly pumped by coherent light. We derive the autocorrelation function of the field emergent from the cavity. We show that the autocorrelation function can be expressed in terms of the atomic dissipation rate. In order to distinguish between the resonant and the non-resonant case, we introduce a parameter interpreted as the measure of the relative detuning between the pump laser and the excited atom frequency. By selecting the parameter time, we determine the lifetime of the excited atom. This method constitutes an interesting alternative for internal atomic parameter determination.

The equation-of-motion method is used to solve the energy spectra of one-dimensional quantum systems with symmetric polynomial potentials. This method is an approximation method, but it is not a perturbative approach since it is not based on the existence of some kind of small parameter. After a general discussion, we calculate the approximate energy spectra to some particular examples.

The extended mapping method has been used to derive some new exact solutions of the KdV–mKdV equation as a combination of some Jacobian elliptic functions. Solutions in the limiting cases have also been studied.

Semi-classical approximate values of the Stark parameters for several lines of Sn II are reported in this paper. They were calculated using a set of wavefunctions obtained from Hartree–Fock relativistic calculations. Stark widths for 80 lines of Sn II arising from ns ²S_1/2, np ²P_{1/2, 3/2}, nd ²D_{3/2, 5/2} and nf ²F_{5/2, 7/2} levels of Sn II have been calculated in this way. Stark widths are presented as a function of temperature for an electron density of 10¹⁷ cm⁻³. Our results are compared with available experimental data. Stark shifts of five lines with experimental value in the bibliography have been studied normalized to an electron density of 10¹⁷ cm⁻³. Common regularities for the Stark width of several lines of singly ionized tin have been discussed.

The interaction of singly and multiply charged ions with DNA can play a crucial role in biological radiation damage processes. In proton or heavy-ion therapy, high-energy ion beams are already employed for tumour treatment. The most relevant bio-molecular processes occur in the Bragg-peak region and involve primary as well as secondary ions of much lower kinetic energies. Bio-molecular mechanisms relevant in this regime are largely unexplored. First steps towards a better understanding of the relevant processes are ion-induced ionization and fragmentation studies on DNA building blocks, either isolated or in clusters or deposited on surfaces. In this paper, we will briefly summarize the current state of knowledge regarding low-energy ion interactions with DNA building blocks and try to identify important open questions.