467 research outputs found

    Selective addressing of high-rank atomic polarization moments

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    We describe a method of selective generation and study of polarization moments of up to the highest rank κ=2F\kappa=2F possible for a quantum state with total angular momentum FF. The technique is based on nonlinear magneto-optical rotation with frequency-modulated light. Various polarization moments are distinguished by the periodicity of light-polarization rotation induced by the atoms during Larmor precession and exhibit distinct light-intensity and frequency dependences. We apply the method to study polarization moments of 87^{87}Rb atoms contained in a vapor cell with antirelaxation coating. Distinct ultra-narrow (1-Hz wide) resonances, corresponding to different multipoles, appear in the magnetic-field dependence of the optical rotation. The use of the highest-multipole resonances has important applications in quantum and nonlinear optics and in magnetometry.Comment: 5 pages, 6 figure

    Enhancement of Magneto-Optic Effects via Large Atomic Coherence

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    We utilize the generation of large atomic coherence to enhance the resonant nonlinear magneto-optic effect by several orders of magnitude, thereby eliminating power broadening and improving the fundamental signal-to-noise ratio. A proof-of-principle experiment is carried out in a dense vapor of Rb atoms. Detailed numerical calculations are in good agreement with the experimental results. Applications such as optical magnetometry or the search for violations of parity and time reversal symmetry are feasible

    Робочий зошит до конспекту лекцій з дисциплін “Основи побудови мікропроцесорних систем керування”, “Мікропроцесорна техніка”, “Програмні засоби систем керування” для студентів спеціальностей АГ – 8.092501 Автоматизоване управління технологічними процесами; АТ,ME – 8.091401 Системи управління й автоматики; СМ – 8.091501 Комп`ютерні системи та мережі

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    Дані методичні вказівки призначуються для вивчення апаратних та програмних засобів мікропроцесорних систем управління (МПС). У процесі вивчення дисципліни "Мікропроцесорні системи" студенти вивчають структуру, архітектуру, сигнали та системи команд однокристального мікроконтролера К1816 ВЕ51. Розглянуті питання організації паралельного та послідовного вводу- виводу, оганізація мікропроцесорних контролерів МПК). Схемні рішення, які приведені у методичних вказівках можуть бути використані при виконанні курсових і дипломних проектів студентами спеціальностей "Комп’ютеризовані системи управління і автоматики" (АТ) і "Автоматизація технологічних процесів гірничих підприємств" (АГ) та "Комп’ютерні системи та мережі" (СМ)

    Competitive stochastic noises in coherently driven two-level atoms and quantum interference

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    A system of coherently-driven two-level atoms is analyzed in presence of two independent stochastic perturbations: one due to collisions and a second one due to phase fluctuations of the driving field. The behaviour of the quantum interference induced by the collisional noise is considered in detail. The quantum-trajectory method is utilized to reveal the phase correlations between the dressed states involved in the interfering transition channels. It is shown that the quantum interference induced by the collisional noise is remarkably robust against phase noise. This effect is due to the fact that the phase noise, similarly to collisions, stabilizes the phase-difference between the dressed states.Comment: accepted for publication in J. Opt.

    Multiband theory of quantum-dot quantum wells: Dark excitons, bright excitons, and charge separation in heteronanostructures

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    Electron, hole, and exciton states of multishell CdS/HgS/CdS quantum-dot quantum well nanocrystals are determined by use of a multiband theory that includes valence-band mixing, modeled with a 6-band Luttinger-Kohn Hamiltonian, and nonparabolicity of the conduction band. The multiband theory correctly describes the recently observed dark-exciton ground state and the lowest, optically active, bright-exciton states. Charge separation in pair states is identified. Previous single-band theories could not describe these states or account for charge separation.Comment: 10 pages of ReVTex, 6 ps figures, submitted to Phys. Rev.

    Free-fall expansion of finite-temperature Bose-Einstein condensed gas in the non Thomas-Fermi regime

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    We report on our study of the free-fall expansion of a finite-temperature Bose-Einstein condensed cloud of 87Rb. The experiments are performed with a variable total number of atoms while keeping constant the number of atoms in the condensate. The results provide evidence that the BEC dynamics depends on the interaction with thermal fraction. In particular, they provide experimental evidence that thermal cloud compresses the condensate.Comment: 8 pages, 4 figure

    Energetic and spatial bonding properties from angular distributions of ultraviolet photoelectrons: application to the GaAs(110) surface

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    Angle-resolved ultraviolet photoemission spectra are interpreted by combining the energetics and spatial properties of the contributing states. One-step calculations are in excellent agreement with new azimuthal experimental data for GaAs(110). Strong variations caused by the dispersion of the surface bands permit an accurate mapping of the electronic structure. The delocalization of the valence states is discussed analogous to photoelectron diffraction. The spatial origin of the electrons is determined, and found to be strongly energy dependent, with uv excitation probing the bonding region.Comment: 5 pages, 3 figures, submitted for publicatio
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