Vacuum quantum effect for curved boundaries in static Robertson–Walker space–time

The energy–momentum tensor for a massless conformally coupled scalar field in the region between two curved boundaries in k=−1 static Robertson–Walker space–time is investigated. We assume that the scalar field satisfies the Dirichlet boundary condition on the boundaries. k=−1 Robertson–Walker space is conformally related to the Rindler space, as a result we can obtain vacuum expectation values of energy–momentum tensor for conformally invariant field in Robertson–Walker space from the corresponding Rindler counterpart by the conformal transformation.     

Deformed “commutative” Chern–Simons’ system

Noncommutative Chern–Simons’ system is non-perturbatively investigated at a full deformed level. A deformed “commutative” phase space is found by a non-canonical change between two sets of deformed variables of noncommutative space. It is explored that in the “commutative” phase space all calculations are similar to the case in commutative space. Spectra of its energy and angular momentum of the Chern–Simons’ system are obtained at the full deformed level. The noncommutative–commutative correspondence is clearly showed. Formalism for the general dynamical system is briefly presented. Some subtle points are clarified.     

Oscillation modes,transient chaos and its control in a modulation-doped semiconductor double-heterostructure

The nonlinear dynamics of real space transfer for a 2D electron gas in a system of two adjacent Al _x Ga_1–x As/GaAs-heterolayers under parallel current conduction has been investigated numerically. The mechanisms which have been taken into account are transfer of electrons by thermionic emission and nonresonant tunneling and the delayed dielectric relaxation of the interface potential barrier. We predict bistability of an asymmetric and a symmetric self-generated oscillation mode, a quasiperiodic route to chaos and transient chaos with mean transient times obeying a universal critical scaling law. Unstable periodic orbits of the chaotic repeller can be stabilized by a simple delayed feedback control, thus providing a widely tunable semiconductor oscillator.     

Simple type and the boundary of moduli space

We measure, in two distinct ways, the extent to which the boundary region of moduli space contributes to the “simple type” condition of Donaldson theory. Using the natural geometric representative of μ(pt) defined in [L. Sadun, Commun. Math. Phys. 178 (1996) 107–113], the boundary region of moduli space contributes of the homology required for simple type, regardless of the topology or geometry of the underlying 4-manifold. The simple type condition thus reduces to the interior of the (k+1)th ASD moduli space, intersected with two representatives of (4 times) the point class, being homologous to 58 copies of the kth moduli space. This is peculiar, since the only known embeddings of the kth moduli space into the (k+1)th involve Taubes gluing, and the images of such embeddings lie entirely in the boundary region.When using the natural de Rham representatives of μ(pt) considered by Witten [Commun. Math. Phys. 117 (1988) 353], the boundary region contributes of what is needed for simple type, again regardless of the topology or geometry of the underlying 4-manifold. The difference between this and the geometric representative answer is not contradictory, as the contribution of a fixed region to the Donaldson invariants is geometric, not topological.     

Development of a Ti:Sapphire DIAL system for pollutant monitoring and meteorological applications

A mobile differential absorption lidar system with SHG of Nd-YAG pumped Ti : Sapphire laser has been developed and tested. Mixing between Ti : Sapphire and Nd-YAG fundamentals extends the wavelength range to UV–vis region (250–480 nm), which is ideal to monitor tropospheric pollutants. Preliminary water vapor profiles in the near IR region (in our case 800–900 nm) are presented and discussed.     

On lateral competition in dynamic neural networks

Artificial neural networks connected homogeneously, which use retinal image processing methods, are considered. We point out that there are probably two different types of lateral inhibition for each neural element by the neighboring ones—due to the negative connection coefficients between elements and due to the decreasing neuron's response to a too high input signal. The first case is characterized by stable dynamics, which is given by the Lyapunov function, while in the second case, stability is absent and two-dimensional dynamic chaos occurs if the time step in the integration of model equations is large enough. The continuous neural medium approximation is used for analytical estimation in both cases. The results is the partition of the parameter space into domains with qualitatively different dynamic modes. Computer simulations confirm the estimates and show that joining two-dimensional chaos with symmetries provided by the initial and boundary conditions may produce patterns which are genuine pieces of art.Scientific-Research Institute of Radiophysics. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 37, No. 8, pp. 1030–1052, August, 1994.     

Spatial deterministic chaos in optical systems and methods of its modeling

The phenomenon of spatial deterministic chaos is described. A transition from an ordinary differential equation to a discrete map is justified for modeling of the chaos. Methods of studying the chaos dynamics in this model are suggested. It is established how the physical properties of a nonlinear ring interferometer influence the structure of charts of the Lyapunov exponents. The approaches developed in the present study allow an optical cryptosystem to be optimized.__________Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 65–71, December, 2004.     

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The dynamics of cold atoms in conservative optical lattices obviously depends on the geometry of the lattice. But very similar lattices may lead to deeply different dynamics. In a 2D optical lattice with a square mesh, it is expected that the coupling between the degrees of freedom leads to chaotic motions. However, in some conditions, chaos remains marginal. The aim of this paper is to understand the dynamical mechanisms inhibiting the appearance of chaos in such a case. As the quantum dynamics of a system is defined as a function of its classical dynamics – e.g. quantum chaos is defined as the quantum regime of a system whose classical dynamics is chaotic – we focus here on the dynamical regimes of classical atoms inside a well. We show that when chaos is inhibited, the motions in the two directions of space are frequency locked in most of the phase space, for most of the parameters of the lattice and atoms. This synchronization, not as strict as that of a dissipative system, is nevertheless a mechanism powerful enough to explain that chaos cannot appear in such conditions.     

A Submillimeter Homodyne Transmit and Receive System (HTRS) for detecting weak signals from reflectors

A Submillimetre Homodyne Transmit and Receive System has been developed to operate in the 500–2000 GHz region. The system is based around an Optically Pumped Submillimetre laser system and an optical processing system. The system will be described along with our test results which show detectivities of better than –130dBm at 693GHz.     

Ensemble Dynamics of Intermittency and Power-Law Decay

A spectral decomposition of the Frobenius–Perron operator is constructed for one-dimensional maps with intermittent chaos, using the method of coherent states. A technique using the spectral density function is applied to the the well-known cusp map, which generates weak type-II intermittency. Higher-order corrections are obtained to the leading 1/t long-time behavior of the x–x autocorrelation.     

Localization of pulse signal in randomly layered medium

It is shown that in a medium with randomly layered inhomogeneities, a nonstationary pulse signal emitted by a plane (one-dimensional) source is localized in a closed region of space due to the interference of multiply scattered fields. A wave packet emitted by a point source in such a medium is channeled along the layers.Institute of Radio Physics and Electronics, Academy of Sciences of Ukraine. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 35, Nos. 3, 4, pp. 246–251, March–April, 1992.     

光与物质相互作用系统中的量子Fisher信息和自旋压缩

Fisher信息是估计理论中的重要概念,最近发现与量子信息中的纠缠判据具有密切联系.非旋波近似条件下,Dicke模型经典相空间表现为混沌动力学特征.本文详细考察了Dicke模型描述的光与物质相互作用系统中量子Fisher信息和自旋压缩动力学特性.结果表明:在短时瞬态情况下,无论初态处于规则区域还是混沌区域系统均表现为纠缠性质;但在长时稳态情况下,初态处于规则区域时系统纠缠消失,而初态处于混沌区域时系统则一直存在纠缠.通过与系统自旋压缩动力学性质相比较,发现量子Fisher信息可以更有效地刻画量子混沌.进一步考察初态处于规则和混沌区域时系统密度矩阵和纯度的动力学演化特性,发现混沌导致系统退相干现象发生,说明量子Fisher信息对混沌更敏感.     

Short wave pass and long wave pass dichroic coating at 45° on zinc selenide substrate for dual band thermal imager

In dual band thermal imager dichroic coating plays a vital role in separating 3–5 μm and 7.5–10.5 μm wavelength region for observing better image quality from two different channels. In this work a study has been carried out on the design and fabrication of short and long wave pass dichroic coating at 45° on zinc selenide flat substrate. These dichroic coated optics can be used to separate 3–5 μm (in reflection or transmission channel) and 7.5–10.5 μm (in transmission or reflection channel) wavelength region. An inhomogeneous refractive index profile which is a polynomial of 5th order was considered to design the high and low wave pass dichroic coating on zinc selenide substrate. The inhomogeneous profile was then approximated with five steps from substrate to air medium. These steps were then converted in terms of durable coating materials of six and seven layer stack for short and long wave pass dichroic coating respectively. The coating material combination used was germanium as high index material and IR-F625 as low index material. Result achieved for short wave pass dichroic filter was 94% average transmission in 3–5 μm region and 95% average reflection in 7.5–10.5 μm region. Similarly, result achieved for long wave pass dichroic filter was 95% average reflection in 3–5 μm region and 94% average transmission in 7.5–10.5 μm.     

Experimental robust synchronization of hyperchaotic circuits

Even if complete synchronization between two chaotic circuits can be reached only when the systems are identical, in this paper we address the robustness of synchronization in the presence of parameter mismatches between the coupled circuits in the case of hyperchaotic behavior. In particular, a master–slave scheme based on negative feedback [T. Kapitaniak, Synchronization of chaos using continuous control, Phys. Rev. E 50 (1994) 1642–1644] is considered and the strategy to design the slave system as an observer of the master is given. With the proposed approach, based on the concept of the Master Stability Function, the two circuits are coupled through a unique scalar signal. Experimental results obtained from two hyperchaotic circuits will be presented in order to show that synchronization occurs widely in the range of electronic component tolerances.     

Partially coherent acoustic images in layered refractive waveguides

This paper is devoted to the development of partially coherent acoustic images in plane-layered waveguides. In particular, we present the results of analysis of a structure by the frequency-contrast characteristic (FCC) of the imaging system, which determines the spatial resolution of images and shows the potentialities of spatial filtering of the space spectrum's components for different coherence of a lighting field.Institute of Applied Physics Russian Academy of Sciences, Nizhny Novgorod. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 38, Nos. 1–2, pp. 127–133, January–February, 1995.     

Development of a tunable IR lidar system

A differential absorption lidar system (DIAL) based on a continuously tunable optical parametric amplifier (OPA) pumped by a Nd : YAG laser (200 mJ at λ=355 nm) operating at a maximum pulse repetition rate of 100 Hz has been developed. The system provides continuously tunable coherent radiation in the Visible–near IR range (0.4–2.5 μm), allowing to perform DIAL measurements in a spectral region where most of atmospheric constituents and pollutants display absorption lines. The spectral width of the OPA system is line-narrowed by using a master oscillator dye laser as seeder, achieving a linewidth of 0.04 cm⁻¹ (FWHM), a spectral purity larger than 99% and a frequency stability better than 1 pm h⁻¹, with an output energy in the IR of 1–10 mJ. The OPA system was used to perform DIAL measurements in the lower troposphere. Preliminary results in terms of water vapor content and aerosol backscattering profiles are presented and discussed.     

Synchronization of diffusionally coupled nonautonomous chaotic pendulums

We consider the phenomenon of mutual synchronization of a chain of diffusionally coupled nonautonomous pendulums in a chaotic regime with increase in the diffusion factor. The system dynamics for different boundary conditions is studied. The boundary of the synchronization existence region is obtained qualitatively. The method of comparison systems and the method of Liapunov's functions are used in this paper.State University, Nizhny Novgorod. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 38, Nos. 1–2, pp. 69–73, January–February, 1995.     

Regular and chaotic quantum dynamics in atom-diatom reactive collisions

A new microirreversible 3D theory of quantum multichannel scattering in the three-body system is developed. The quantum approach is constructed on the generating trajectory tubes which allow taking into account influence of classical nonintegrability of the dynamical quantum system. When the volume of classical chaos in phase space is larger than the quantum cell in the corresponding quantum system, quantum chaos is generated. The probability of quantum transitions is constructed for this case. The collinear collision of the Li + (FH) → (LiF) + H system is used for numerical illustration of a system generating quantum (wave) chaos. The text was submitted by the authors in English.     

Spectral distribution of the photoconductivity of cadmium diphosphide

The spectral distribution of the photoconductivity of CdP₂ crystals has been studied in the range 0.3–1.5 m. The intrinsic photoconductivity has been found to be localized in the region of the near-surface space charge. The role of the natural superlattice in the photoconductivity is considered.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 96–98, July, 1991.     

Transmission grating spectrograph with on-line recording of XUV soft X-ray spectra from laser produced plasmas

The setting up and on-line operation of a transmission grating spectrograph in the XUV soft X-ray region is described. The detector was a microchannel plate–image intensifier combination, and the output of the image intensifier was coupled to a CCD camera–frame grabber system through an imaging lens. The spectrograph could be operated in the 5–20 Å range with 0.6 Å spectral resolution and in the 5–50 Å range with 1 Å resolution, respectively. The high sensitivity of the detector enables single shot operation, which is useful for several laser plasma interaction studies.