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We have studied the effect of external pumping on the dynamics of the entanglement of two two-level atoms interacting with a cavity mode. It is shown that a sequence of well detuned pulses of the classical field leads to the dynamical formation of an extended plateau-like zone of high level atomic entanglement with the duration much longer than the period of Rabi oscillations. The dissipation reduces the amplitude of the entanglement, however practically does not change the width of such zones. [ABSTRACT FROM AUTHOR]

We examine the waveguide properties of a spherical stack∶ a system of optical layers deposited onto the microsphere substrate, with arbitrary ratios between thicknesses of layers and a wavelength of propagating electromagnetic radiation. Frequency dependencies of the reflection coefficient and impedance of the stack are studied. An appropriate matrix formalism is developed to generalize the matrix method well-known for the plane case, into the case of the spherical layer geometry. The material losses and random deviations of thicknesses of layers are taken into account. The quarter-wave length layers are studied in details. Our numerical calculations have revealed the narrow gap of a transparency in a zone of high reflectance of a stack under the suitable parameters. The spectrum of eigenfrequencies of a spherical resonator coating by the dielectric stack has been calculated. It has been found that Q factor electromagnetic oscillations in such a system exponentially grows with increasing number of layers in the stack, but only for eigenfrequencies which are in the zone of high a stack reflection. [ABSTRACT FROM AUTHOR]