1,085 research outputs found

    Evolution equation of quantum tomograms for a driven oscillator in the case of the general linear quantization

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    The symlectic quantum tomography for the general linear quantization is introduced. Using the approach based upon the Wigner function techniques the evolution equation of quantum tomograms is derived for a parametric driven oscillator.Comment: 11 page

    Mobile laboratory explosive destruction of natural materials: investigation of the behavior of ice and limestone under explosive loading

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    In the paper, the behavior of ice and natural limestone under explosion condition was investigated. The objects of study were the river ice and natural limestone quarry on Siberia. The practical significance of research due to the need to increase production of oil and gas in permafrost regions, the fight against ice jams, etc. We organized a mobile laboratory ''Explosive destruction of the natural materials" at the National Research Tomsk State University. The main purpose of the laboratory is express analyzing of explosive destruction of natural materials. The diameters and depths of explosive craters in the limestone and explosive lane in the ice were obtained. The results can be used to test new models and numerical methods for calculating shock and explosive loading of different materials, including ice

    Bound, virtual and resonance SS-matrix poles from the Schr\"odinger equation

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    A general method, which we call the potential SS-matrix pole method, is developed for obtaining the SS-matrix pole parameters for bound, virtual and resonant states based on numerical solutions of the Schr\"odinger equation. This method is well-known for bound states. In this work we generalize it for resonant and virtual states, although the corresponding solutions increase exponentially when rr\to\infty. Concrete calculations are performed for the 1+1^+ ground and the 0+0^+ first excited states of 14N^{14}\rm{N}, the resonance 15F^{15}\rm{F} states (1/2+1/2^+, 5/2+5/2^+), low-lying states of 11Be^{11}\rm{Be} and 11N^{11}\rm{N}, and the subthreshold resonances in the proton-proton system. We also demonstrate that in the case the broad resonances their energy and width can be found from the fitting of the experimental phase shifts using the analytical expression for the elastic scattering SS-matrix. We compare the SS-matrix pole and the RR-matrix for broad s1/2s_{1/2} resonance in 15F{}^{15}{\rm F}Comment: 14 pages, 5 figures (figures 3 and 4 consist of two figures each) and 4 table

    Electron Bloch Oscillations and Electromagnetic Transparency of Semiconductor Superlattices in Multi-Frequency Electric Fields

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    We examine phenomenon of electromagnetic transparency in semiconductor superlattices (having various miniband dispersion laws) in the presence of multi-frequency periodic and non-periodic electric fields. Effects of induced transparency and spontaneous generation of static fields are discussed. We paid a special attention on a self-induced electromagnetic transparency and its correlation to dynamic electron localization. Processes and mechanisms of the transparency formation, collapse, and stabilization in the presence of external fields are studied. In particular, we present the numerical results of the time evolution of the superlattice current in an external biharmonic field showing main channels of transparency collapse and its partial stabilization in the case of low electron density superlattices

    Dispersionful analogues of Benney's equations and NN-wave systems

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    We recall Krichever's construction of additional flows to Benney's hierarchy, attached to poles at finite distance of the Lax operator. Then we construct a ``dispersionful'' analogue of this hierarchy, in which the role of poles at finite distance is played by Miura fields. We connect this hierarchy with NN-wave systems, and prove several facts about the latter (Lax representation, Chern-Simons-type Lagrangian, connection with Liouville equation, τ\tau-functions).Comment: 12 pages, latex, no figure

    Quantum dynamics, dissipation, and asymmetry effects in quantum dot arrays

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    We study the role of dissipation and structural defects on the time evolution of quantum dot arrays with mobile charges under external driving fields. These structures, proposed as quantum dot cellular automata, exhibit interesting quantum dynamics which we describe in terms of equations of motion for the density matrix. Using an open system approach, we study the role of asymmetries and the microscopic electron-phonon interaction on the general dynamical behavior of the charge distribution (polarization) of such systems. We find that the system response to the driving field is improved at low temperatures (and/or weak phonon coupling), before deteriorating as temperature and asymmetry increase. In addition to the study of the time evolution of polarization, we explore the linear entropy of the system in order to gain further insights into the competition between coherent evolution and dissipative processes.Comment: 11pages,9 figures(eps), submitted to PR
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