摘要:

We derive Hamiltonians for quantum networks of Ising-type structure. These networks can be composed of simple optical elements such as beam splitters or parameteric amplifiers, similar structures appear also in a variety of systems with many intersecting energy levels. We give exact forms for the Hamiltonians and discuss their implications in certain limits.

ISSN:0950-0340    

DOI:10.1080/09500340008231401

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The problem of a two-level atom interacting with a non-monochromatic radiation pulse is studied in the resonant approximation for arbitrary detunings, and without the resonant approximation. By using the time-dependent theory of perturbation the analytical expressions for the transition probability and induced dipole moment of the atom are obtained. It is shown that the upper level population of the atom exhibits oscillations that are absent in the resonant approximation. The temporal shape of the pulse is shown to affect significantly the atomic transition probability. The behaviour of the transition probability and dipole moment spectrum for arbitrary pulse shapes, phases and detunings is investigated. The interference between the spectral components arising in nonlinear processes is shown to play a considerable role in the formation of a dipole moment spectrum.

ISSN:0950-0340    

DOI:10.1080/09500340008231402

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

We deal with the two-dimensional scattering problem of an incoming monochromatic p-polarized wave inside a tip—surface junction of a local probe microscope. We find enhancement of the field with lateral size less than 40nm and a maximum of the order of 104. This result is very encouraging for experimental work on the aperture less-SNOM (perturbation mode). The solution is obtained by means of the method of discrete sources.

ISSN:0950-0340    

DOI:10.1080/09500340008231403

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

It is shown that the symmetrically ordered moments of boson operators for a single boson mode can be reconstructed from the corresponding moments of the Radon transform of the Wigner quasiprobability for discrete sets of equidistant inequivalent angles which solve the circle division problem. This reconstruction is sometimes simpler than the corresponding reconstruction of the normally ordered moments where one first has to multiply the Radon transform with Hermite polynomials in comparison to power functions for symmetrically ordered moments and then to integrate. The connection to the reconstruction for the general class ofs-ordered moments is established. The transition from discrete sets of angles to integration over angles via averaging over the discrete angles is made. The results are applied to displaced squeezed thermal states. It is shown how the ordered moments for these states can be explicitly found from the calculated Radon transform of the Wigner quasiprobability. The obtained formulae for these moments possess independent interest since they contribute to the discussion of the properties of the most general class of states with quasiprobabilities of Gaussian form with many possible special cases as, for example, squeezed coherent states and squeezed thermal states.

ISSN:0950-0340    

DOI:10.1080/09500340008231404

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

We establish general conditions that complex and real valued pupil filters must satisfy to produce an identical axial response. We show several conditions that permit the generation of families of filters with identical axial response but with different transverse response. In particular we show results for supergaussian rings that depend on three parameters. Two of the parameters can determine the shape of the axial response achieving arbitrarily high focal depth. For a given axial response the third parameter controls the transverse response, permitting the attainment of super-resolution up to a limit. Loss of light throughput and the sidelobe's increase are also studied. The axial behaviour is also studied for the case of optical systems with high aperture. The introduction of a generalized pupil function allows the determination of the conditions to obtain axially invariant pupil filters.

ISSN:0950-0340    

DOI:10.1080/09500340008231405

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

We show an approach to the correction of defocusing in stacks of images of 3D scenes using the second order moment of the-co-occurrence matrix, a concept similar to that of the structure function used in scattering and Brownian motion. The local value of these functions shows a clear maximum in the regions of correct focus. The concepts are applied to simulations, to actual plane images and to 3D scenes.

ISSN:0950-0340    

DOI:10.1080/09500340008231406

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

We study the effect of the hypersensitization with sodium sulphite in Agfa-Gevaert 8E75HD holographic plates in reflection holograms. An enhancement of energetic sensitivity and diffraction efficiency is observed with low solvent effects when Agfa-Gevaert 8E75HD are pre-processed. A 2–5 times increase of the sensitivity, together with temporal stability, is observed in reflection holograms.

ISSN:0950-0340    

DOI:10.1080/09500340008231407

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A study of diffraction-free and diffraction-limited propagation of light with transverse amplitude in sech through a planar waveguide with hyperbolic secant refractive index profile is presented. Analytical solutions by the stationary phase method are obtained. A particular case is analysed.

ISSN:0950-0340    

DOI:10.1080/09500340008231408

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A knowledge of the local refractive index variations and size distribution of scatterers in biological tissue is required to understand the physical processes involved in light-tissue interaction. This paper describes a method for modelling the complicated soft tissue, based on the fractal approach, permitting numerical evaluation of the phase functions and four optical properties of tissue—scattering coefficient, reduced scattering coefficient, backscatter-ing coefficient, and anisotropy factor—by the use of the Mie scattering theory. A key assumption of the model is that refractive index variations caused by microscopic tissue elements can be treated as particles with size distribution according to the power law. The model parameters, such as refractive index, incident wavelength, and fractal dimension, that are likely to affect the predictions of optical properties are investigated. The results suggest that the fractal dimension used to describe how biological tissue can be approximated by particle distribution is highly dependent on how the continuous distribution is discretized. The optical properties of the tissue significantly depend on the refractive index of tissue, implying that the refractive index of the particles should be carefully chosen in the model in order accurately to predict the optical properties of the tissue concerned.

ISSN:0950-0340    

DOI:10.1080/09500340008231409

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The standard Fresnel diffraction wave field from an aperture in a plane screen involves an integral over the aperture area. Here it is reduced to an aperture edge integral instead. The reduction really amounts to performing one integral but can be considered as the reduction of the ‘Maggi-Rubinovics’ edge formula from Kirchhoff optics to paraxial (i.e. Fresnel) optics.

ISSN:0950-0340    

DOI:10.1080/09500340008231410

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor