On the role of coherent states in quantum foundations

Coherent states, and the Hilbert space representations they generate, provide ideal tools to discuss classical/quantum relationships. In this paper we analyze three separate classical/quantum problems using coherent states, and show that useful connections arise among them. The topics discussed are: (1) a truly natural formulation of phase space path integrals; (2) how this analysis implies that the usual classical formalism is ``simply a subset'' of the quantum formalism, and thus demonstrates a universal coexistence of both the classical and quantum formalisms; and (3) how these two insights lead to a complete analytic solution of a formerly insoluble family of nonlinear quantum field theory models.Comment: ICQOQI'2010, Kiev, Ukraine, May-June 2010, Conference Proceedings (9 pages

Nondispersive X-ray emission analysis for geochemical exploration

Nondispersive X-ray emission technique uses lightweight, and rugged X-ray fluorescence units. The X-ray pulse-height spectra is excited by radioactive isotope sources. The technique is applicable for quantitative and qualitative analyses on complex chemical systems, and satisfies the goals for a lunar geochemical exploration device

E2 component in subcoulomb breakup of ^{8}B

We calculate the angular distribution and total cross section of the ^{7}Be fragment emitted in the break up reaction of ^{8}B on ^{58}Ni and ^{208}Pb targets at the subCoulomb beam energy of 25.8 MeV, within the non-relativistic theory of Coulomb excitation with proper three-body kinematics. The relative contributions of the E1, E2 and M1 multipolarities to the cross sections are determined. The E2 component makes up about 65% and 40% of the ^{7}Be total cross section for the ^{58}Ni and ^{208}Pb targets respectively. We find that the extraction of the astrophysical S-factor, S_{17}(0), for the ^{7}Be(p,\gamma)^8B reaction at solar energies from the measurements of the cross sections of the ^{7}Be fragment in the Coulomb dissociation of ^{8}B at sub-Coulomb energies is still not free from the uncertainties of the E2 component.Comment: Revised version (correcting earlier errors) submitted to Phys. Letts.

Dark solitons in laser radiation build-up dynamics

We reveal the existence of slowly-decaying dark solitons in the radiation build-up dynamics of bright pulses in all-normal dispersion mode-locked fiber lasers, numerically modeled in the framework of a generalized nonlinear Schr\"odinger equation. The evolution of noise perturbations to quasi-stationary dark solitons is examined, and the significance of background shape and soliton-soliton collisions on the eventual soliton decay is established. We demonstrate the role of a restoring force in extending soliton interactions in conservative systems to include the effects of dissipation, as encountered in laser cavities, and generalize our observations to other nonlinear systems

Experiences with the design and implementation of flutter suppression systems

Research efforts aim at flutter suppression are discussed. The application of active controls technology to reduce the aeroelastic response of aircraft structures is discussed. Feedback control, control law design processes and synthesis, wind tunnel studies, and delta-wing wind tunnel models are discussed

Towards 'smart lasers': self-optimisation of an ultrafast pulse source using a genetic algorithm

Short-pulse fibre lasers are a complex dynamical system possessing a broad space of operating states that can be accessed through control of cavity parameters. Determination of target regimes is a multi-parameter global optimisation problem. Here, we report the implementation of a genetic algorithm to intelligently locate optimum parameters for stable single-pulse mode-locking in a Figure-8 fibre laser, and fully automate the system turn-on procedure. Stable ultrashort pulses are repeatably achieved by employing a compound fitness function that monitors both temporal and spectral output properties of the laser. Our method of encoding photonics expertise into an algorithm and applying machine-learning principles paves the way to self-optimising `smart' optical technologies

On the transport of charged particles in turbulent fields: comparison of an exact solution with the quasilinear approximation

The problem of charged-particle transport in a magnetic field which is solely a function of time is solved. The solution is obtained exactly, to all orders in the field, in the limit of large wavelengths normal to the magnetic field. It is shown that the usual quasilinear, Fokker-Planck approximation is equal to the exact solution in the limit of times large compared with the correlation time of the fluctuating field. This is just the regime where the approximation has been used in the past, and this special case thus gives some support to the standard approximation techniques

Numerical least-square method for resolving complex pulse height spectra

Linear least-square method resolves complex pulse height spectra, allowing for calculation of relative intensity, of statistical variance based on counting statistics of the correlation between library components, and of the goodness-of-fit chi square. Some applications are to gamma-ray, X ray, and charged-particle spectroscopy

Twist transition of nematic hyperbolic hedgehogs

Stability of an idealized hyperbolic hedgehog in a nematic liquid crystal against a twist transition is investigated by extending the methodology of Rüdinger and Stark [Liq. Cryst. 26, 753 (1999)], where the hedgehog is confined between two concentric spheres. In the ideal hyperbolic-hedgehog the molecular orientation is assumed to rotate proportionally with respect to the inclination angle, θ (and in the opposite sense). However, when splay, k11, and bend, k33, moduli differ this proportionality is lost and the liquid crystal deforms relative to the ideal with bend and splay. Although slight, these deformations are shown to significantly shift the transition if k11/k33 is small. By increasing the degree of confinement the twist transition can be inhibited, a characteristic both hyperbolic and radial hedgehogs have in common. The twist transition of a hyperbolic defect that accompanies a particle is found to be well predicted by the earlier stability analysis of a thick shell