339 research outputs found
Statistics of light in Raman and Brillouin nonlinear couplers
Statistical properties of optical fields in nonlinear couplers composed of
two waveguides in which Raman or Brillouin processes (with classical pumping)
are in operation and which are mutually connected through the Stokes and/or
anti-Stokes linear interactions are investigated within the framework of
generalized superposition of coherent fields and quantum noise. Heisenberg
equations describing the couplers are solved both analytically under special
conditions and numerically in general cases. Regimes for nonclassical
properties of optical fields, such as sub-Poissonian photon-number statistics,
negative reduced moments of integrated intensity and squeezing of quadrature
fluctuations are discussed for the cases of single and compound fields. General
results are compared with those from short-length approximation.Comment: LATEX, 20 pages, 19 PostScript figure
Quantum dynamics and statistics of two coupled down-conversion processes
In the framework of Heisenberg-Langevin theory the dynamical and statistical
effects arising from the linear interaction of two nondegenerate
down-conversion processes are investigated. Using the strong-pumping
approximation the analytical solution of equations of motion is calculated. The
phenomena reminiscent of Zeno and anti-Zeno effects are examined. The
possibility of phase-controlled and mismatch-controlled switching is
illustrated.Comment: 17 pages, 7 figure
Quantum state estimation
New algorithm for quantum state estimation based on the maximum likelihood
estimation is proposed. Existing techniques for state reconstruction based on
the inversion of measured data are shown to be overestimated since they do not
guarantee the positive definiteness of the reconstructed density matrix.Comment: 4 pages, twocolumn Revte
Classification of Jaw Bone Cysts and Necrosis via the Processing of Orthopantomograms
The authors analyze the design of a method for automatized evaluation of parameters in orthopantomographic images capturing pathological tissues developed in human jaw bones. The main problem affecting the applied medical diagnostic procedures consists in low repeatability of the performed evaluation. This condition is caused by two aspects, namely subjective approach of the involved medical specialists and the related exclusion of image processing instruments from the evaluation scheme. The paper contains a description of the utilized database containing images of cystic jaw bones; this description is further complemented with appropriate schematic repre¬sentation. Moreover, the authors present the results of fast automatized segmentation realized via the live-wire method and compare the obtained data with the results provided by other segmentation techniques. The shape parameters and the basic statistical quantities related to the distribution of intensities in the segmented areas are selected. The evaluation results are provided in the final section of the study; the authors correlate these values with the subjective assessment carried out by radiologists. Interestingly, the paper also comprises a discussion presenting the possibility of using selected parameters or their combinations to execute automatic classification of cysts and osteonecrosis. In this context, a comparison of various classifiers is performed, including the Decision Tree, Naive Bayes, Neural Network, k-NN, SVM, and LDA classifica¬tion tools. Within this comparison, the highest degree of accuracy (85% on the average) can be attributed to the Decision Tree, Naive Bayes, and Neural Network classifier
Quantum statistics and dynamics of nonlinear couplers with nonlinear exchange
In this paper we derive the quantum statistical and dynamical properties of
nonlinear optical couplers composed of two nonlinear waveguides operating by
the second subharmonic generation, which are coupled linearly through
evanescent waves and nonlinearly through nondegenerate optical parametric
interaction. Main attention is paid to generation and transmission of
nonclassical light, based on a discussion of squeezing phenomenon, normalized
second-order correlation function, and quasiprobability distribution functions.
Initially coherent, number and thermal states of optical beams are considered.
In particular, results are discussed in dependence on the strength of the
nonlinear coupling relatively to the linear coupling. We show that if the Fock
state enters the first waveguide and the vacuum state enters the
second waveguide, the coupler can serve as a generator of squeezed vacuum state
governed by the coupler parameters. Further, if thermal fields enter initially
the waveguides the coupler plays similar role as a microwave Josephson-junction
parametric amplifier to generate squeezed thermal light.Comment: 32 pages, 10 figure
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