661 research outputs found
A Novel Method for Polarization Squeezing with Photonic Crystal Fibers
Photonic Crystal Fibers can be tailored to increase the effective Kerr
nonlinearity, while producing smaller amounts of excess noise compared to
standard silicon fibers. Using these features of Photonic Crystal Fibers we
create polarization squeezed states with increased purity compared to standard
fiber squeezing experiments. Explicit we produce squeezed states in counter
propagating pulses along the same fiber axis to achieve near identical
dispersion properties. This enables the production of polarization squeezing
through interference in a polarization type Sagnac interferometer. We observe
Stokes parameter squeezing of -3.9 +/- 0.3dB and anti-squeezing of 16.2 +/-
0.3dB.Comment: 7 pages, 5 figure
Lyapunov Mode Dynamics in Hard-Disk Systems
The tangent dynamics of the Lyapunov modes and their dynamics as generated
numerically - {\it the numerical dynamics} - is considered. We present a new
phenomenological description of the numerical dynamical structure that
accurately reproduces the experimental data for the quasi-one-dimensional
hard-disk system, and shows that the Lyapunov mode numerical dynamics is linear
and separate from the rest of the tangent space. Moreover, we propose a new,
detailed structure for the Lyapunov mode tangent dynamics, which implies that
the Lyapunov modes have well-defined (in)stability in either direction of time.
We test this tangent dynamics and its derivative properties numerically with
partial success. The phenomenological description involves a time-modal linear
combination of all other Lyapunov modes on the same polarization branch and our
proposed Lyapunov mode tangent dynamics is based upon the form of the tangent
dynamics for the zero modes
Supersymmetric approach to exactly solvable systems with position-dependent effective masses
We discuss the relationship between exact solvability of the Schr\"{o}dinger
equation with a position-dependent mass and the ordering ambiguity in the
Hamiltonian operator within the frame of supersymmetric quantum mechanics. The
one-dimensional Schr\"{o}dinger equation, derived from the general form of the
effective mass Hamiltonian, is solved exactly for a system with exponentially
changing mass in the presence of a potential with similar behaviour, and the
corresponding supersymmetric partner Hamiltonians are related to the
effective-mass Hamiltonians proposed in the literature.Comment: 12 pages article in LaTEX (uses standard article.sty). Please check
http://www1.gantep.edu.tr/~ozer for other studies of Nuclear Physics Group at
University of Gaziantep. [arXiv admin note: excessive overlap with
quant-ph/0306065 and "Supersymmetric approach to quantum systems with
position-dependent effective mass" by A. R. Plastino, A. Rigo, M. Casas, F.
Garcias, and A. Plastino - Phys. Rev. A 60, 4318 - 4325 (1999)
Potential algebra approach to position dependent mass Schroedinger equation
It is shown that for a class of position dependent mass Schroedinger equation
the shape invariance condition is equivalent to a potential symmetry algebra.
Explicit realization of such algebras have been obtained for some shape
invariant potentials
Time-Accurate Computations of Isolated Circular Synthetic Jets in Crossflow
Results from unsteady Reynolds-averaged Navier-Stokes computations are described for two different synthetic jet flows issuing into a turbulent boundary layer crossflow through a circular orifice. In one case the jet effect is mostly contained within the boundary layer, while in the other case the jet effect extends beyond the boundary layer edge. Both cases have momentum flux ratios less than 2. Several numerical parameters are investigated, and some lessons learned regarding the CFD methods for computing these types of flow fields are summarized. Results in both cases are compared to experiment
Nonsingular potentials from excited state factorization of a quantum system with position dependent mass
The modified factorization technique of a quantum system characterized by
position-dependent mass Hamiltonian is presented. It has been shown that the
singular superpotential defined in terms of a mass function and a excited state
wave function of a given position-dependent mass Hamiltonian can be used to
construct non-singular isospectral Hamiltonians. The method has been
illustrated with the help of a few examples.Comment: Improved version accepted in J. Phys.
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