Laser phase modulation approaches towards ensemble quantum computing

Selective control of decoherence is demonstrated for a multilevel system by generalizing the instantaneous phase of any chirped pulse as individual terms of a Taylor series expansion. In the case of a simple two-level system, all odd terms in the series lead to population inversion while the even terms lead to self-induced transparency. These results also hold for multiphoton transitions that do not have any lower-order photon resonance or any intermediate virtual state dynamics within the laser pulse-width. Such results form the basis of a robustly implementable CNOT gate.Comment: 10 pages, 4 figures, PRL (accepted

A Stepwise Planned Approach to the Solution of Hilbert's Sixth Problem. III : Measurements and von Neumann Projection/Collapse Rule

Supmech, the universal mechanics developed in the previous two papers, accommodates both quantum and classical mechanics as subdisciplines (a brief outline is included for completeness); this feature facilitates, in a supmech based treatment of quantum measurements, an unambiguous treatment of the apparatus as a quantum system approximated well by a classical one. Taking explicitly into consideration the fact that observations on the apparatus are made when it has `settled down after the measurement interaction' and are restricted to macroscopically distinguishable pointer readings, the unwanted superpositions of (system + apparatus) states are shown to be suppressed; this provides a genuinely physics based justification for the (traditionally \emph{postulated}) von Neumann projection/collapse rule. The decoherence mechanism brought into play by the stated observational constraints is free from the objections against the traditional decoherence program.Comment: 29 pages; one section and two references added; results unchange

A Landau fluid model for warm collisionless plasmas

A Landau fluid model for a collisionless electron-proton magnetized plasma, that accurately reproduces the dispersion relation and the Landau damping rate of all the magnetohydrodynamic waves, is presented. It is obtained by an accurate closure of the hydrodynamic hierarchy at the level of the fourth order moments, based on linear kinetic theory. It retains non-gyrotropic corrections to the pressure and heat flux tensors up to the second order in the ratio between the considered frequencies and the ion cyclotron frequency.Comment: to appear in Phys. Plasma

On trapped surface formation in gravitational collapse II

Further to our consideration on trapped surfaces in gravitational collapse, where pressures were allowed to be negative while satisfying weak energy condition to avoid trapped surface formation, we discuss here several other attempts of similar nature in this direction. Certain astrophysical aspects are pointed out towards examining the physical realization of such a possibility in realistic gravitational collapse

An Investigation of Solving Multidimensional Multiphase Flow: Streamline front tracking method

In the present paper we have studied streamline front tracking method for two and three-phase flow contains capillary forces. Increased demand for assessment of uncertainties and history matching require fast and accurate flow simulations on multiple plausible geological models on a routinely basis. On the other hand, conventional reservoir simulators fail to fulfill this need, and there seems to be trend within the petroleum industry to simulate reduced sets of equations. Hence, typically streamline or front tracking methods are used to solve the hyperbolic Buckley Leverette equation for two-phase flow. In this paper we consider models of multi-phase flow which do capillary forces, allowing for three phase. In particular we shall investigate a streamline front tracking method and to account for capillary effects we use operator splitting. Thus we compare the streamline front tracking method (SFTM) with a fast marching method (FFM) and a modified method of characteristics (MMOC). Keywords: Streamline front tracking method, three-phase immiscible flow, modified method of characteristics, Cartesian grid, Riemann solver, Fast Marching method

A Current Perspectives of Corrected Operator Splitting (OS) for Systems

In this paper we studied mathematical models for fluid flow often involve systems of convection-diffusion equations as a main ingredient. Operator splitting - one splits the time evolution into partial steps to separate the effects of convection and diffusion.  In the present paper it has been shown that that the temporal splitting error can be significant when there is a shock present in the solution, is well-understood for scalar convection – diffusion equation. Keywords: Convection diffusion, convection solver, front tracking method, nonlinear error mechanism, operator splitting

An analytical approach to Heat Transfer in Single and Multiphase Systems

This paper deals main physical processes arising during phase change have been investigated. The heat exchange within a single phase, many engineering technologies involve multiphase systems. Hence the problems dealing with phase change is the movement of phase interface with the release with the absorption of latent heat at this interface. The problems are highly nonlinear and thermophysical properties are typically different on each side of the phase interface.  Therefore, analytical solutions are available only for a limited class of one-dimensional problems- pure materials or fluids in infinite or semi-infinite domains.  In the present paper we demonstrate phase change heat transfer in pure liquids and materials as well as multicomponent systems. The multiphase systems have (i.e., solid, liquid, or gas phase) including one or more components. Although the governing equations vary for each type of multiphase system (i.e solid-liquid, liquid-gas, etc.,), the overall features of the physical and mathematical models are analogous. Theses continuum models are based on a mixture formulation or an interface tracking formulation. In the mixture approach, the control volume consists of a homogeneous mixture encompassing both (or all) phases. Mixture of interface tracking formulations are demonstrated in this studies. Key words: Interface tracking, multi-phase flow, phase interface, interfacial energy balance, scalar transport, entropy, two fluid modeling

Neutrino parameters from matter effects in PeeP_{ee} at long baselines

We show that the earth matter effects in the ${\rm {\nu_e \to \nu_e}}$ survival probability can be used to cleanly determine the third leptonic mixing angle $\theta_{13}$ and the sign of the atmospheric neutrino mass squared difference, $\Delta m^2_{31}$, using a $\beta$-beam as a $\nu_e$ source.Comment: 4 pages, 4 eps figures; comments and references added, to appear in Phys. Rev.