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[en] We present an indirect imaging method that measures both amplitude and phase information from a transmissive target. Our method is based on an optical eigenmode decomposition of the light intensity and the first-order cross correlation between a target field and these eigenmodes. We demonstrate that such optical eigenmode imaging does not need any a priori knowledge of the imaging system and corresponds to a compressive full-field sampling, leading to high image extraction efficiencies. Finally, we discuss the implications with respect to second-order correlation imaging.
[en] The ground-state properties of neutral hard-core bosons trapped in an optical two-leg ladder in the presence of an artificial magnetic field are studied. For a weak field, two separated peaks appear in the momentum distribution as a signature of the Meissner state in which bosons, carrying persistent currents on each leg, condense into finite-momentum states, while for a strong field, a central peak and tiny bumps associated with the vortex lattice structure indicate that the ground state is the vortex state.
[en] Error estimates for perturbative approximations to solutions of systems with small nonlinearities are limited in scope. For single oscillator systems, and for systems with more than one degree of freedom that depend on a single phase, the error between the approximation and the full solution is bounded by O(ε) for times of O(1/ε), where -ε-=AB1 is the strength of the perturbation. Otherwise, error estimates exist only on approximations to the action variables. Most of the error estimates have been derived for systems in which the unperturbed Hamiltonian is itself nonlinear. No information is available on errors in the phases. For the study of the topological structure of the solutions in phase space this may be sufficient. However, for good long-term approximations to the full solution of a dynamical system, this situation is not satisfactory. Through a sequence of examples of growing complexity, of nonlinearly coupled harmonic oscillators, we have shown that, by applying minimal normal forms (MNE) to the dynamical equations obeyed by the phases of all the degrees of freedom, the errors in the approximations to solutions are reduced significantly in comparison with the usual procedure for computing the perturbative approximations. The normal form is given as a formal power series in the expansion parameter of the problem. Using the freedom inherent in any perturbation expansion, the normal form may be formally truncated into a finite sum, the MNF. In the present work this idea is applied to the phase part of the normal form equations
[en] Energy levels of states connected by a symmetry of the Hamiltonian normally should be degenerate. In self-consistent field theories, when only one of a pair of single-particle levels connected by a symmetry of the full Hamiltonian is occupied, the degeneracy is split and the unoccupied level often lies below the occupied one. Inversions of neutron-proton (charge) and time-reversal doublets in odd nuclei, charge doublets in even nuclei with a neutron excess, and spin-orbit doublets in spherical configurations with spin-unsaturated shells are examined. The origin of the level inversion is investigated, and the following explanation offered. Unoccupied single-particle levels, from a calculation in an A-particle system, should be interpreted as levels of the (A + 1)-particle system. When the symmetry-related level, occupied in the A-particle system, is also calculated in the (A + 1)-particle system it is degenerate with or lies lower than the other. That is, when both levels are calculated in the (A + 1)-particle system, they are not inverted. It is demonstrated that the usual prescription to occupy the lowest-lying orbitals should be modified to refer to the single-particle energies calculated in the (A + 1)- or the (A - 1)-particle system. This observation is shown to provide a justification for avoiding an oscillation of occupancy between symmetry-related partners in successive iterations leading to a self-consistency. It is pointed out that two degenerate determinants arise from occupying one or the other partner of an initially degenerate pair of levels and then iterating to self-consistency. The existence of the degenerate determinants indicates the need for introducing correlations, either by mixing the two configurations or by allowing additional symmetry-breaking (resulting in a more highly deformed non-degenerate configuration). 2 figures, 3 tables, 43 references
[en] One of the study targets is to determine the dispersion characteristics of plasma inversely by examining the signal propagating through the plasma after injecting the known signal into the plasma. As the first stage, this experiment intends to measure the group velocity of plasma waves using continuous waves. This time, the experiment has been carried out to judge the possibility of the basic portion of the principle in real observation. The group velocity of plasma waves (Bernstein mode waves) is the gradient of the tangent of the curve that represents the relation of their dispersion. Transmitted signal waves are frequency-modulated as a method of measuring this gradient. Having determined from the data obtained in the first experiment, the theoretically calculated curve of the velocity did not agree with the measured values, but the trend was similar. Then the second experiment was performed. From this result, the limitations of the frequency modulation method were known. The change in static electricity wave intensity owing to the distance from the excitation source comes into question, and it is also influenced by magnetic field. It is concluded that since the voltage really measured is sinusoidal voltage, the fluctuation in the experimental result is due to this sinusoidal term. The elimination of this term should be investigated in the future. (Wakatsuki, Y.)
[en] The mode-conversion characteristics of a few-mode optical waveguide based on adiabatic mode evolution are investigated. The mode-conversion efficiency and cross talks of the configuration are found dependent on the position and angle between the assistant waveguide and the main waveguide, and also the size of the assistant waveguide. By setting the bottoms of the two waveguides at the same plane, the symmetry of the configuration can be broken. The configuration is able to convert each mode to a higher order or lower order mode by launching light from different ports. In particular, mode conversion between the two degenerated LP11 modes can be achieved with wide bandwidth.
[en] The effects of small collisional damping on the mode conversion of an extraordinary wave incident upon a warm magnetoplasma slab are studied. When a converted Bernstein mode is at anti-resonance, the absorption coefficient can be as high as 0.5 at very low collision frequencies
[en] A review is presented of the state of the art in a new direction in quantum electronics based on the use of femtosecond lasers for precision frequency measurements and the development of optical frequency and time standards. (review)
[en] Analogies between gravitation (galactic) plasma and the plasma the decisive role wherein is played by electromagnetic interaction, are considered. Studies on the density and bending waves are carried out. The problem on stability of non collision spherical systems is discussed
[en] A Gordeyev-type integral for the investigation of electrostatic waves in magnetized plasma having a kappa or generalized Lorentzian velocity distribution is derived. The integral readily reduces, in the unmagnetized and parallel propagation limits, to simple expressions involving the Zκ function. For propagation perpendicular to the magnetic field, it is shown that the Gordeyev integral can be written in closed form as a sum of two generalized hypergeometric functions, which permits easy analysis of the dispersion relation for electrostatic waves. Employing the same analytical techniques used for the kappa distribution, it is further shown that the well-known Gordeyev integral for a Maxwellian distribution can be written very concisely as a generalized hypergeometric function in the limit of perpendicular propagation. This expression, in addition to its mathematical conciseness, has other advantages over the traditional sum over modified Bessel functions form. Examples of the utility of these generalized hypergeometric series, especially how they simplify analyses of electrostatic waves propagating perpendicular to the magnetic field, are given. The new expression for the Gordeyev integral for perpendicular propagation is solved numerically to obtain the dispersion relations for the electrostatic Bernstein modes in a plasma with a kappa distribution