Showing papers in "Central European Journal of Physics in 2008"
TL;DR: In this paper, the Optimal Homotopy Asymptotic Method (OHAM) has been applied to thin film flow of a fourth grade fluid down a vertical cylinder and the results reveal that the proposed method is very accurate, effective and easy to use.
Abstract: A new approximate analytical technique to address for non-linear problems, namely Optimal Homotopy Asymptotic Method (OHAM) is proposed and has been applied to thin film flow of a fourth grade fluid down a vertical cylinder. This approach however, does not depend upon any small/large parameters in comparison to other perturbation method. This method provides a convenient way to control the convergence of approximation series and allows adjustment of convergence regions where necessary. The series solution has been developed and the recurrence relations are given explicitly. The results reveal that the proposed method is very accurate, effective and easy to use.
231 citations
TL;DR: In this article, a ring-shaped pseudoharmonic potential was solved for the Schrodinger equation in D-dimensions by using the Nikiforov-Uvarov method, and the radial and angular parts of the wave functions were obtained in terms of orthogonal Laguerre and Jacobi polynomials.
Abstract: A new non-central potential, consisting of a pseudoharmonic potential plus another recently proposed ring-shaped potential, is solved. It has the form \( V(r,\theta ) = \tfrac{1} {8}\kappa r_e^2 \left( {\tfrac{r} {{r_e }} - \tfrac{{r_e }} {r}} \right)^2 + \tfrac{{\beta cos^2 \theta }} {{r^2 sin^2 \theta }} \). The energy eigenvalues and eigenfunctions of the bound-states for the Schrodinger equation in D-dimensions for this potential are obtained analytically by using the Nikiforov-Uvarov method. The radial and angular parts of the wave functions are obtained in terms of orthogonal Laguerre and Jacobi polynomials. We also find that the energy of the particle and the wave functions reduce to the energy and the wave functions of the bound-states in three dimensions.
55 citations
TL;DR: In this paper, the bound-state energy spectrum for the d-dimensional Klein-Gordon equation with scalar S(r) and vector potentials V(r), where the potentials are Coulombic and Kratzer type, was obtained.
Abstract: We apply the Asymptotic Iteration Method to obtain the bound-state energy spectrum for the d-dimensional Klein-Gordon equation with scalar S(r) and vector potentials V(r). When S(r) and V(r) are both Coulombic, we obtain all the exact solutions; when the potentials are both of Kratzer type, we obtain all the exact solutions for S(r) = V(r); if S(r) > V(r) we obtain exact solutions under certain constraints on the potential parameters: in this case, a possible general solution is found in terms of a monic polynomial, whose coefficients form a set of elementary symmetric polynomials.
52 citations
TL;DR: In this paper, a comparison between the usual Pareto distribution and its truncated version is presented, and a possible physical mechanism that produces pareto tails for the distribution of the masses of stars is presented.
Abstract: The Pareto probability distribution is widely applied in dierent fields such us finance, physics, hydrology, geology and astronomy. This note deals with an application of the Pareto distribution to astrophysics and more precisely to the statistical analysis of masses of stars and of diameters of asteroids. In particular a comparison between the usual Pareto distribution and its truncated version is presented. Finally, a possible physical mechanism that produces Pareto tails for the distribution of the masses of stars is presented.
49 citations
TL;DR: In this article, the exact solutions of the D-dimensional radial Schrodinger equation with some molecular potentials, such as pseudoharmonic and modified Kratzer, are obtained.
Abstract: Making an ansatz to the wave function, the exact solutions of the D-dimensional radial Schrodinger equation with some molecular potentials, such as pseudoharmonic and modified Kratzer, are obtained. Restrictions on the parameters of the given potential, δ and ν are also given, where η depends on a linear combination of the angular momentum quantum number l and the spatial dimensions D and δ is a parameter in the ansatz to the wave function. On inserting D = 3, we find that the bound state eigensolutions recover their standard analytical forms in literature.
47 citations
TL;DR: A polycrystalline sample of KCa2Nb5O15 with tungsten bronze structure was prepared by a mixed oxide method at high temperature and a preliminary structural analysis of the compound showed an orthorhombic crystal structure at room temperature as discussed by the authors.
Abstract: A polycrystalline sample of KCa2Nb5O15 with tungsten bronze structure was prepared by a mixed oxide method at high temperature. A preliminary structural analysis of the compound showed an orthorhombic crystal structure at room temperature. Surface morphology of the compound shows a uniform grain distribution throughout the surface of the sample. Studies of temperature variation on dielectric response at various frequencies show that the compound has a transition temperature well above the room temperature (i.e., 105°C), which was confirmed by the polarization measurement. Electrical properties of the material have been studied using a complex impedance spectroscopy (CIS) technique in a wide temperature (31–500°C) and frequency (102–106 Hz) range that showed only bulk contribution and non-Debye type relaxation processes in the material. The activation energy of the compound (calculated from both the loss and modulus spectrum) is same, and hence the relaxation process may be attributed to the same type of charge carriers. A possible ‘hopping’ mechanism for electrical transport processes in the system is evident from the modulus analysis. A plot of dc conductivity (bulk) with temperature variation demonstrates that the compound exhibits Arrhenius type of electrical conductivity.
40 citations
TL;DR: In this paper, the authors present approximate analytical solutions of the radial Schrodinger equation with non-zero l values for the Hulthen potential in the frame of an approximation to the centrifugal potential for any l states.
Abstract: In this paper, using the Exact Quantization Rule, we present approximate analytical solutions of the radial Schrodinger equation with non-zero l values for the Hulthen potential in the frame of an approximation to the centrifugal potential for any l states. The energy levels of all bound states can be easily calculated from the Exact Quantization Rule. Specifically, the normalized analytical wave functions are also obtained. Some energy eigenvalues are numerically calculated and compared with those obtained by other methods such as asymptotic iteration, supersymmetry, numerical integration methods, and the schroedinger Mathematica package.
38 citations
TL;DR: In this article, the Klein-Gordon equation in D-dimensions for a ring-shaped Kratzer potential is solved analytically by means of the conventional Nikiforov-Uvarov method.
Abstract: The Klein-Gordon equation in D-dimensions for a recently proposed ring-shaped Kratzer potential is solved analytically by means of the conventional Nikiforov-Uvarov method. The exact energy bound states and the corresponding wave functions of the Klein-Gordon are obtained in the presence of the non-central equal scalar and vector potentials. The results obtained in this work are more general and can be reduced to the standard forms in three dimensions given by other works.
36 citations
TL;DR: In this paper, the relativistic perihelion precession of Mercury's orbit was investigated using a modified form of the general theory of relativity, which is a remodeled form of Einstein's theories and which retained only experimentally proven principles.
Abstract: Among all the theories proposed to explain the “anomalous” perihelion precession of Mercury’s orbit first announced in 1859 by Le Verrier, the general theory of relativity proposed by Einstein in November 1915 alone could calculate Mercury’s “anomalous” precession with the precision demanded by observational accuracy. Since Mercury’s precession was a directly derived result of the full general theory, it was viewed by Einstein as the most critical test of general relativity from amongst the three tests he proposed. With the advent of the space age, the level of observational accuracy has improved further and it is now possible to detect this precession for other planetary orbits of the solar system — viz., Venus and the Earth. This conclusively proved that the phenomenon of “anomalous” perihelion precession of planetary orbits is a relativistic effect. Our previous papers presented the mathematical model and the computed value of the relativistic perihelion precession of Mercury’s orbit using an alternate relativistic gravitational model, which is a remodeled form of Einstein’s relativity theories, and which retained only experimentally proven principles. In addition this model has the benefit of data from almost a century of relativity experimentation, including those that have become possible with the advent of the space age. Using this model, we present in this paper the computed values of the relativistic precession of Venus and the Earth, which compare well with the predictions of general relativity and are also in agreement with the observed values within the range of uncertainty.
32 citations
TL;DR: In this article, an improved Monte Carlo diffusion model was used to calculate the ground state energies and chemical potentials of parahydrogen clusters of three to forty molecules, using two different p-H 2-p-H2 interactions.
Abstract: An improved Monte Carlo diffusion model is used to calculate the ground state energies and chemical potentials of parahydrogen clusters of three to forty molecules, using two different p-H2-p-H2 interactions. The improvement is due to three-body correlations in the importance sampling, to the time step adjustment and to a better estimation of statistical errors. In contrast to path-integral Monte Carlo results, this method predicts no magic clusters other than that with thirteen molecules.
27 citations
TL;DR: In this article, a new theory explaining the intensity of f-f transitions and the crystal field using an approximation of a strong configuration interaction is proposed, which enables the anomalous influence of excited configurations with charge transfer on some multiplets of the f shell to be taken into account.
Abstract: A new theory explaining the intensity of f-f transitions and the crystal field using an approximation of a strong configuration interaction is proposed. The theory enables the anomalous influence of excited configurations with charge transfer on some multiplets of the f shell to be taken into account. With the help of this theory, a satisfactory description of the absorption transitions and luminescence branching ratios from 1 D 2 and 3 P 0 multiplets for the Pr3+ ion in double molybdates has been achieved for the first time. For further validation the theory, was used to provide a description of Stark splitting of Pr3+ — multiplets in elpasolites and determine the covalence parameters; these parameters were found to be in good agreement with values obtained by the other methods.
TL;DR: In this paper, the quasinormal frequencies of the massive scalar field in the background of a Schwarzchild black hole surrounded by quintessence with the third-order WKB method are presented.
Abstract: We present the quasinormal frequencies of the massive scalar field in the background of a Schwarzchild black hole surrounded by quintessence with the third-order WKB method. The mass of the scalar field u plays an important role in studying the quasinormal frequencies, the real part of the frequencies increases linearly as mass of the field u increases, while the imaginary part in absolute value decreases linearly which leads to damping more slowly than the massless scalar field. The frequencies have a limited value, so it is easier to detect the quasinormal modes. Moreover, owing to the presence of the quintessence, the massive scalar field damps more slowly.
TL;DR: In this paper, the dependence of the ablation rate of aluminium on the fluence of nanosecond laser pulses with wavelengths of 532 nm and respectively 1064 nm was investigated in atmospheric air.
Abstract: The dependence of the ablation rate of aluminium on the fluence of nanosecond laser pulses with wavelengths of 532 nm and respectively 1064 nm is investigated in atmospheric air. The fluence of the pulses is varied by changing the diameter of the irradiated area at the target surface, and the wavelength is varied by using the fundamental and the second harmonic of a Q-switched Nd-YAG laser system. The results indicate an approximately logarithmic increase of the ablation rate with the fluence for ablation rates smaller than ∼6 μm/pulse at 532 nm, and 0.3 μm/pulse at 1064 nm wavelength. The significantly smaller ablation rate at 1064 nm is due to the small optical absorptivity, the strong oxidation of the aluminium target, and to the strong attenuation of the pulses into the plasma plume at this wavelength. A jump of the ablation rate is observed at the fluence threshold value, which is ∼50 J/cm2 for the second harmonic, and ∼15 J/cm2 for the fundamental pulses. Further increasing the fluence leads to a steep increase of the ablation rate at both wavelengths, the increase of the ablation rate being approximately exponential in the case of visible pulses. The jump of the ablation rate at the threshold fluence value is due to the transition from a normal vaporization regime to a phase explosion regime, and to the change of the dimensionality of the hydrodynamics of the plasma-plume.
TL;DR: In this article, the authors report on the fabrication of all transparent heterojunction thin film diodes of the form glass/n-ZnO: Al/p-CuAlO2 produced by a combinatorial chemical and physical technique and on a study of their electro-optical properties.
Abstract: We report on the fabrication of all transparent heterojunction thin film diodes of the form glass/n-ZnO: Al/p-CuAlO2 produced by a combinatorial chemical and physical technique and on a study of their electro-optical properties. The n-ZnO: Al layer was deposited by a sol-gel-dip-coating process whereas the p-CuAlO2 layer was deposited by direct current sputtering techniques. The diode structure, with a total thickness of 1100 nm showed around 60% transmittance in the visible region. The current-voltage characteristics of the device showed a rectifying nature, with a low turn-on voltage around 0.8 V, having a rectification ratio > 50 at ± 2 V. The low turn-on voltage and moderate visible transmittance of the transparent diode indicate its potential application in the field of “Transparent” or “Invisible Electronics”.
TL;DR: In this paper, the electronic energy-band structure, density of states (DOS), and optical properties of AgBO3 in the paraelectric cubic phase have been studied by using density functional theory within the local density approximation for exchange correlation for the first time.
Abstract: The electronic energy-band structure, density of states (DOS), and optical properties of AgBO3 in the paraelectric cubic phase have been studied by using density functional theory within the local density approximation for exchange-correlation for the first time The band structure shows a band gap of 1533 eV (AgNbO3)and 1537 eV (AgTaO3)at (M-⌈)point in the Brillouin zone The optical spectra of AgBO3 in the photon energy range up to 30 eV are investigated under the scissor approximation The real and imaginary parts of the dielectric function and — thus the optical constants such as reflectivity, absorption coefficient, electron energy-loss function, refractive index, and extinction coefficient — are calculated We have also made some comparisons with related experimental and theoretical data that is available
TL;DR: In this paper, the effect of adsorbed Sn atoms as a surfactant on Ge diffusion on a Si(111) surface has been studied by Low Energy Electron Diffraction and Auger Electron Spectroscopy.
Abstract: The effect of adsorbed Sn as a surfactant on Ge diffusion on a Si(111) surface has been studied by Low Energy Electron Diffraction and Auger Electron Spectroscopy. The experimental dependence of Ge diffusion coefficients on the Si(111) surface versus temperature in the presence of adsorbed Sn atoms has been measured in the range from 300 to 650°C. It has been shown that at a Sn coverage of about 1 monolayer the mobility of Ge atoms increases by several orders of magnitude.
TL;DR: In this paper, the authors analyzed the optical ability of left-handed chiral metamaterials by emphasizing their optical ability on the rotation of the plane of polarization of a wave and presented the possibilities of a negative phase velocity, negative and positive propagation constants, and basic electromagnetic properties of this novel medium.
Abstract: In this work, the concept of left-handed chiral metamaterials is analyzed by emphasizing their optical ability on the rotation of the plane of polarization of a wave. The possibilities of a negative phase velocity, negative and positive propagation constants, and basic electromagnetic properties of this novel medium are also presented. After the characterization of left-handed chiral metamaterial, we provide a reflection and transmission study for two planar boundaries of nonchiral-left-handed chiral metamaterial for normal angles of incidence. Some numerical results are also provided to validate the formulation found in the analysis and to show the role of the chirality in the propagation constants, phase velocities, reflection and transmission.
TL;DR: In this paper, the authors used the three body potential model (TBPM) approach to predict the phase transition pressure and pressure variations of elastic constants of transition metal compounds (TiO and TiN) which crystallize in NaCl-structure.
Abstract: The high pressure phase transition and elastic behavior of Transition Metal Compounds (TiO and TiN) which crystallize in NaCl-structure have been investigated using the three body potential model (TBPM) approach. These interactions arise due to the electron-shell deformation of the overlapping ions in crystals. The TBP model consists of a long range Coulomb, three body interactions, and the short-range overlap repulsive forces operative up to the second neighboring ions. The authors of this paper estimated the values of the phase transition pressures, associated volume collapses, and elastic constants, all of which were found to be closer to available experimental data than other calculations. Thus, the TBPM approach promises to predict the phase transition pressure and pressure variations of elastic constants of Transition Metal compounds.
TL;DR: In this paper, the phase transition pressure of Barium chalcogenides (BaO, BaSe and BaTe) was investigated using a three-body interaction potential (MTBIP) approach, modified by incorporating covalency effects.
Abstract: In the present paper we have investigated the high-pressure, structural phase transition of Barium chalcogenides (BaO, BaSe and BaTe) using a three-body interaction potential (MTBIP) approach, modified by incorporating covalency effects. Phase transition pressures are associated with a sudden collapse in volume. The phase transition pressures and associated volume collapses obtained from TBIP show a reasonably good agreement with experimental data. Here, the transition pressure, NaCl-CsCl structure increases with decreasing cation-to-anion radii ratio. In addition, the elastic constants and their combinations with pressure are also reported. It is found that TBP incorporating a covalency effect may predict the phase transition pressure, the elastic constants and the pressure derivatives of other chalcogenides as well.
TL;DR: In this article, complex multilayer thin film filters for optical applications have been designed, prepared and characterized in the first stage, optimized individual film layers of TiO2, Ta2O5, and SiO2 are deposited and characterized optically and structurally before the deposition of multilayered structures.
Abstract: Complex multilayer thin film filters for optical applications have been designed, prepared and characterized in this work. E-beam reactive evaporation technique has been used as a deposition process. In the first stage, optimized individual film layers of TiO2, Ta2O5, and SiO2 are deposited and characterized optically and structurally before the deposition of multilayered structures. The filter designs are based upon 33 layered SiO2/TiO2 and SiO2/Ta2O5 configurations on glass substrate. These designs are optimized to achieve wideband transmission in the visible spectrum. After deposition, the two filter configurations are characterized optically and structurally using spectrophotometery, atomic force microscopy (AFM), X-ray diffraction (XRD) and scanning electron microscopy (SEM). SiO2/Ta2O5/glass filter has been found sensitive to deposition conditions since high absorption is observed in multilayered configuration for the as-deposited samples. Post-deposition annealing of the filter in the temperature range 150 to 250°C was also performed in order to study the effect of temperature on absorption and spectral characteristics of the filter. Comparison of the two filter configurations was also performed to analyze their suitability for optical applications. Adhesion of the two filters was found to be very good by means of tape-peel test.
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TL;DR: In this article, the joint propagation of a periodically modulated field and a pulse of different frequency in an optical fiber is discussed, and the effects of discreteness are predicted both in the temporal and in the spatial domain.
Abstract: In this paper we discuss the joint propagation of a periodically modulated field and a pulse of different frequency in an optical fiber. The pulse experiences the action of an index lattice induced via cross-phase modulation by the periodic field. We predict effects of discreteness to show up both in the temporal and in the spatial domain. For large walk-off between the two fields one should observe Bloch oscillations in frequency space, where discrete diffraction is expected to occur for equal velocities of both waves.
TL;DR: In this article, the effect of a strong electric field on the dc conduction of these amorphous bulk samples was investigated using the gap-type electrode configuration, and the Pool-Frenkel high-field effect was observed at electrical fields of about 103-104 V/cm; then the lowering factor of the potential barrier, the high frequency dielectric constant and the refractive index of these glasses were determined.
Abstract: The ternary 70P2O5-10Li2MoO4-20Li2O and 70P2O5-10Na2MoO4-20Na2O glasses, prepared by the press-melt quenching technique, were studied at temperatures between 298 and 418 K for their high dc electric field properties. For the above purpose, the effect of a strong electric field on the dc conduction of these amorphous bulk samples was investigated using the gap-type electrode configuration. At low electric fields, the current-voltage (I — V) characteristics have a linear shape, while at high electric fields (> 103 V/cm), bulk samples show nonlinear effects (nonohmic conduction). Current-voltage curves show increasing departure from Ohm’s law with increasing current density, leading to critical phenomena at a maximum voltage (threshold voltage), known as switching (switch from a low-conduction state to a higher-conduction state at threshold voltage). The Pool-Frenkel high-field effect was observed at electrical fields of about 103–104 V/cm; then the lowering factor of the potential barrier, the high frequency dielectric constant, and the refractive index of these glasses were determined.
TL;DR: In this article, the authors identified 1298 compact groups of galaxies (CGs) at the neighbourhood radius of R = 1.2 Mpc by three-dimensional cluster analysis.
Abstract: From the volume-limited MAIN galaxy sample of the SDSS Data Release 6 (SDSS6), we have identified 1298 compact groups of galaxies (CGs) at the neighbourhood radius of R = 1.2 Mpc by three-dimensional cluster analysis. In order to compile the CG catalog, we also estimated velocity dispersion, virial radius, virial mass and crossing time of CGs. In addition, our results show that properties of galaxies may not correlate with merging frequencies.
TL;DR: In this paper, the electrical properties of polycrystalline samples of Ba4SrRTi3V7O30 (R=Sm and Dy), members of the tungsten-bronze family, were prepared using a high-temperature, solid-state reaction technique and studied their electrical properties (using complex impedance spectroscopy) in a wide range of temperature (31-500°C) and frequency (1 kHz-1 MHz).
Abstract: Polycrystalline samples of Ba4SrRTi3V7O30 (R=Sm and Dy), members of the tungsten-bronze family, were prepared using a high-temperature, solid-state reaction technique and studied their electrical properties (using complex impedance spectroscopy) in a wide range of temperature (31–500°C) and frequency (1 kHz-1 MHz). Preliminary structural (XRD) analyses of these compounds show the formation of single-phase, orthorhombic structures at room temperature. The scanning electron micrographs (SEM) provided information on the quality of the samples and uniform distribution of grains over the entire surface of the samples. Detailed studies of the dielectric properties suggest that they have undergone ferroelectric-paraelectric phase transition well above the room temperatures (i.e., 432 and 355°C for R= Sm and Dy, respectively, at frequency 100 kHz). Measurements of electrical conductivity (ac and dc) as a function of temperature suggest that the compounds have semiconducting properties much above the room temperature, with negative temperature coefficient of resistance (NTCR) behavior. The existence of ferroelectricity in these compounds was confirmed from a polarization study.
TL;DR: In this paper, an ab initio study of the structural, electronic and thermodynamic properties of TlX(X=P,As) was performed using the plane-wave pseudopotential approach to the density-functional theory within the LDA and GGA approximations implemented in VASP (Viena Ab-initio Simulation Package).
Abstract: We present an ab initio study of the structural, electronic and thermodynamic properties of TlX(X=P,As). The plane-wave pseudopotential approach to the density-functional theory within the LDA and GGA approximations implemented in VASP (Viena Ab-initio Simulation Package) is used. The calculated lattice parameter, elastic constants, and band structures are compared with other available theoretical results, and good agreement is obtained. In addition, we have calculated the transition pressure (Pt) from zinc-blende (ZB) to (rock-salt) NaCl structures, and have examined some thermodynamic properties.
TL;DR: The results show that for a suitable value of the frequency, an increase in focal pressure leads to a decrease in the required duration of the treatment and is associated with less heating of the surrounding normal tissue.
Abstract: In this paper, the finite-element method (FEM) simulation of ultrasound brain surgery is presented. The overheating problem of the post-target bone, which is one of the limiting factors for a successful ultrasound brain surgery, is considered. In order to decrease bone heating, precise choices of frequency, focal pressure, and scanning path are needed. The effect of variations in the mentioned scanning parameters is studied by means of the FEM. The resulting pressure and temperature distributions of a transdural ultrasound brain surgery are simulated by employing the FEM for solving the Helmholtz and bioheat equations in the context of a two-dimensional MRI-based brain model. Our results show that for a suitable value of the frequency, an increase in focal pressure leads to a decrease in the required duration of the treatment and is associated with less heating of the surrounding normal tissue. In addition, it is shown that at a threshold focal pressure, the target temperature reaches toxic levels whereas the temperature rise in the bone is minimal. Wave reflections from sinus cavities, which result in constructive interference with the incoming waves, are one of the reasons for overheating of the bone and can be avoided by choosing a suitable scanning path.
TL;DR: In this article, the paraxial complex geometrical optics (CGO) was proposed to describe Gaussian beam diffraction in arbitrary smoothly inhomogeneous media, including lens-like waveguides.
Abstract: The method of paraxial complex geometrical optics (CGO) is presented, which describes Gaussian beam diffraction in arbitrary smoothly inhomogeneous media, including lens-like waveguides. By way of an example, the known analytical solution for Gaussian beam diffraction in free space is presented. Paraxial CGO reduces the problem of Gaussian beam diffraction in inhomogeneous media to the system of the first order ordinary differential equations, which can be readily solved numerically. As a result, CGO radically simplifies the description of Gaussian beam diffraction in inhomogeneous media as compared to the numerical methods of wave optics. For the paraxial on-axis Gaussian beam propagation in lens-like waveguide, we compare CGO solutions with numerical results for finite differences beam propagation method (FD-BPM). The CGO method is shown to provide 50-times higher rate of calculation then FD-BPM at comparable accuracy. Besides, paraxial eikonal-based complex geometrical optics is generalized for nonlinear Kerr type medium. This paper presents CGO analytical solutions for cylindrically symmetric Gaussian beam in Kerr type nonlinear medium and effective numerical solutions for the self-focusing effect of Gaussian beam with elliptic cross section. Both analytical and numerical solutions are shown to be in a good agreement with previous results, obtained by other methods.
TL;DR: The optimization of the well-known universal procedure proposed by Barenco et al. is proposed and can be applied to any quantum circuit containing generalized Toffoli gates, including basic quantum gate circuits.
Abstract: Any unitary operation in quantum information processing can be implemented via a sequence of simpler steps — quantum gates. However, actual implementation of a quantum gate is always imperfect and takes a finite time. Therefore, searching for a short sequence of gates — efficient quantum circuit for a given operation, is an important task. We contribute to this issue by proposing optimization of the well-known universal procedure proposed by Barenco et al. [Phys. Rev. A 52, 3457 (1995)]. We also created a computer program which realizes both Barenco’s decomposition and the proposed optimization. Furthermore, our optimization can be applied to any quantum circuit containing generalized Toffoli gates, including basic quantum gate circuits.
TL;DR: In this paper, a new approach for determination of refractive index dispersion n(λ) and thickness d of thin films of negligible absorption and weak dispersion is proposed, based on determination of the phase thickness of the film in the spectral region of measured transmittance data All points of measured spectra are included in the calculations.
Abstract: A new approach for determination of refractive index dispersion n(λ) (the real part of the complex refractive index) and thickness d of thin films of negligible absorption and weak dispersion is proposed The calculation procedure is based on determination of the phase thickness of the film in the spectral region of measured transmittance data All points of measured spectra are included in the calculations Barium titanate thin films are investigated in the spectral region 038–078 μm and their n(λ) and d are calculated The approach is validated using Swanepoel’s method and it is found to be applicable for relatively thin films when measured transmittance spectra have one minimum and one maximum only
TL;DR: In this paper, four simple statistical microscopic models are used to derive BBR exergy, which consist of combinations of quantum and classical descriptions of the state occupation number and entropy, respectively.
Abstract: There is a long term debate in literature about the exergy of blackbody radiation (BBR). Most authors contributing to this dispute used classical thermodynamics arguments. The objective of this paper is to propose a statistical thermodynamics approach. This gives new perspectives to previous results. Four simple statistical microscopic models are used to derive BBR exergy. They consist of combinations of quantum and classical descriptions of the state occupation number and entropy, respectively. In all four cases the BBR exergy (or exergy flux density) is given by the internal energy (or energy flux density) times an efficiency-like factor containing the environment temperature and the blackbody radiation temperature. One shows that Petela-Landsberg-Press efficiency is the “exact” result while the Jeter (Carnot) efficiency corresponds to the classical approximation. Other two (new) approximate efficiency-like factors are also reported.