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Detuning-Dependent Narrowing of Mollow Triplet Lines of Driven Quantum Dots

JOURNAL OF EXPERIMENTAL AND THEORETICAL PHYSICS 2014年第4期118卷 655-661页

作者： Saiko, A. P. Fedaruk, R. Markevich, S. A. Natl Acad Sci Belarus Sci Pract Mat Res Ctr Minsk 220072 BELARUS Univ Szczecin Inst Phys PL-70451 Szczecin Poland

We study the two-time correlation function and the resonance fluorescence spectrum of a semi-conductor quantum dot excited by a strong off-resonant laser pulse. The obtained analytic expressions exhibit a specific detuning-dependent damping of Rabi oscillations of the dressed quantum dot as well as a detuning-dependent width of Mollow triplet lines. In the absence of pure dephasing, the central peak of the triplet is broadened upon increasing detuning, but the blue- and red-side peaks are narrowed. We demonstrate that the pure dephasing processes can invert these dependences. A crossover between the regimes of detuning-dependent narrowing and broadening of the side and central peaks is identified. The predicted effects are consistent with recent experimental results and numerical calculations.

关键词： Narrowing Mollow Triplet time correlation functions semiconductor quantum boxes Triplets Pulsed lasers narrowing Quantum dots numerical calculation

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Dynamics and dynamic light scattering properties of Brownian particles under laser radiation pressure

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PURE AND APPLIED OPTICS 1998年第5期7卷 1001-1012页

作者： Harada, Y Asakura, T Kitami Inst Technol Dept Comp Sci Kitami Hokkaido 0908507 Japan Hokkai Gakuen Univ Fac Engn Chuo Ku Sapporo Hokkaido 0640926 Japan

Dynamics and light-scattering properties of Brownian particles in colloidal suspensions under the influence of the radiation pressure force of an illuminating laser beam are investigated by means of computer simulations using the Fokker-Planck equation and generalized Lorenz-Mie theory. Dynamic behaviour of the particles and a temporal correlation function of intensity fluctuations of the light scattered by these particles are calculated for various factors of particle size and power of the illuminating laser beam. Results of the simulations support the experimental observations of deformation in the temporal correlation functions of the scattered light and their dependences on the size of the particles and the power of the laser. From simulation results for the dynamics of particles, it is found that these changes in the correlation function arise from suppression of the random motion of the particles in the radial direction of the laser beam and induction of an average uniform motion in the beam propagation direction.

关键词： time correlation functions Laser radiation Light scattering Dynamic Light Scattering Computer Simulation particles laser beams illumination RADIATION PRESSURE dynamics Colloids experimental observation PARTICLE MOTION Power lasers correlation function

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Oscillations in dynamic correlations of binary liquids

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PHYSICA A 1997年第3-4期243卷 229-242页

作者： Lee, JC UNIV SO MISSISSIPPI COMP SCI PROGRAMHATTIESBURGMS 39406

Molecular dynamics simulations are performed for a binary liquid mixture (alpha + beta) to measure, among others, the collective velocity auto-correlation function Z(m)(t) and the time correlation function of the concentration fluctuations F-m(t). Both alpha-alpha and beta-beta pairs of molecules interact through the same Lenard-Jones potential, but alpha-beta pairs interact only through the repulsive part of the potential. From the results for the relaxation time of F-m(t), we estimate the mutual diffusion coefficients. All measurements probing the individual molecular motions indicate that the molecules execute randomly diffusing motions both at T > T-C and T < T-C. The measurements probing their collective motions indicate otherwise. At T > T-C, the results are as expected from those of the individual motions. At T < T-C, the results indicate cooperative behavior which is not evident in the individual motions. Most importantly, we observe an oscillatory mode of collective motions which is analogous to the optical phonons in two-component crystals.

关键词： Molecular-dynamics Diffusion-coefficients Mixtures Relaxation time time correlation functions Oscillations Molecular Dynamics Optical phonon OSCILLATION MODES Cooperative Behavior mixtures diffusion coefficient Binary dynamic liquids Molecular Dynamics Simulation

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Comparative study of temperature dependent orientational relaxation in a model thermotropic liquid crystal and in a model supercooled liquid

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JOURNAL OF CHEMICAL PHYSICS 2007年第20期126卷 4906-1-4906-6-0页

作者： Chakrabarti, Dwaipayan Bagchi, Biman Indian Inst Sci Solid State & Struct Chem Unit Bangalore 560012 Karnataka India

Recent optical Kerr effect experiments have revealed a power law decay of the measured signal with a temperature independent exponent at short-to-intermediate times for a number of liquid crystals in the isotropic phase near the isotropic-nematic transition and supercooled molecular liquids above the mode coupling theory critical temperature. In this work, the authors investigate the temperature dependence of short-to-intermediate time orientational relaxation in a model thermotropic liquid crystal across the isotropic-nematic transition and in a binary mixture across the supercooled liquid regime in molecular dynamics simulations. The measure of the experimentally observable optical Kerr effect signal is found to follow a power law decay at short-to-intermediate times for both systems in agreement with recent experiments. In addition, the temperature dependence of the power law exponent is found to be rather weak. As the model liquid crystalline system settles into the nematic phase upon cooling, the decay of the single-particle second-rank orientational time correlation function exhibits a pattern that is similar to what has been observed for supercooled liquids. (C) 2007 American Institute of Physics.

关键词： LENNARD-JONES MIXTURE GLASS-FORMING LIQUID ISOTROPIC-PHASE ENERGY LANDSCAPE COUPLING THEORY DYNAMICS SIMULATION EXTENSION ULTRAFAST BEHAVIOR Power law Optical Kerr effect temperature dependence liquids simulating dynamics LIQUID MOLDING time correlation functions crystals,liquid-thermotropic

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time correlations of intensity in the case of light transmission through an inhomogeneous medium

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OPTICS AND SPECTROSCOPY 1998年第5期84卷 791-796页

作者： Kuz'min, L Romanov, VP Inst Precis Calculat & Databases St Petersburg 194291 Russia St Petersburg State Univ Inst Phys St Petersburg 198904 Russia

The behavior of the time correlation function of intensity of Light transmitted through a layer of a strongly inhomogeneous medium is investigated. The correlation function is represented as a series in scattering multiplicity that admits fundamental simplifications at long times. The major contribution for sufficiently long times or small thicknesses of an inhomogeneous medium is shown to be made by low-multiplicity scattering. The expression for an the time correlation function valid fos all times for samples of arbitrary thickness is derived in the approximation of double scattering. Detailed numerical analysis of the results obtained is carried out.

关键词： time correlation functions Scattering Light transmission time DEPENDENCE correlation function inhomogeneous media broadcasting

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QUANTUM-MECHANICAL SIMULATION OF CHARGE TRANSPORT IN VERY SMALL SEMICONDUCTOR STRUCTURES

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IEEE TRANSACTIONS ON ELECTRON DEVICES 1989年第6期36卷 1009-1014页

作者： YALABIK, MC NEOFOTISTOS, G DIFF, K GUO, H GUNTON, JD LEHIGH UNIV DEPT PHYSBETHLEHEMPA 18105 TEMPLE UNIV CTR ADV COMPUTAT SCIPHILADELPHIAPA 19122 TEMPLE UNIV DEPT PHYSPHILADELPHIAPA 19122

A quantum-mechanical simulation method of charge transport in very small semiconductor devices is presented that is based on the numerical solution of the time-dependent Schrodinger equation (coupled self-consistently to the Poisson equation to determine the electrostatic potential in the device). Carrier transport is considered within the effective mass approximation, while the effects of the electron-phonon interaction are included in an approximation that is consistent with the results of the perturbation theory and gives the correct two-point time correlation function. Numerical results for the transient behaviour of a planar ultrasubmicrometer three-dimensional GaAs MESFETs (gate length of 26 nm) are also presented. They indicate that extremely fast gate-step response times (switching times) characterize such short-channel GaAs devices.

关键词： effective mass time correlation functions analog approach approximation gallium arsenides perturbation theory MESFETs Poisson equation electron-phonon interactions Transient performance ELECTROSTATIC POTENTIAL Schrodinger equation Semiconductor devices Carrier transport Semiconductor materials

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OPTICS IN TERMS OF OBSERVABLE QUANTITIES

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NUOVO CIMENTO 1954年第6期12卷 884-888页

作者： WOLF, E Department of Astronomy The University Manchester England

Space-time correlation functions are defined which express the correlation between components of the electromagnetic field vectors in stationary fields. These functions form sets of 3×3 matrices, the individual elements of which obey the wave equation. Unlike the field vectors which are not measurable at the high frequencies encountered in Optics our correlation functions may be determined with the help of standard optical instruments. The results enable a unified treatment of theories of partial coherence and partial polarization to be obtained, and suggest a formulation of a wide branch of Optics in terms of observable quantities only

关键词： time correlation functions Optical Devices set SETTING Electromagnetic fields Fields High frequency Optics Wave equation Cloning Vectors correlation function theories Partial

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Two-phonon absorption operator in spectroscopy

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CHEMICAL PHYSICS LETTERS 2013年 555卷 92-95页

作者： Toutounji, Mohamad UAE Univ Coll Sci Dept Chem Al Ain U Arab Emirates

While the raising operator (a) over cap (+) does not have eigenvectors, coherent states are eigenvectors of the lowering operator (a) over cap. Therefore, operating with the operator exp[k (a) over cap (+2)] on coherent states poses a challenge, where k is an arbitrary constant. The result of this operation on coherent states has not yet been reported in a closed form. A closed-form expression for this problem is derived. The applicability and correctness of the result are tested by calculating the electronic dipole moment time correlation function and the corresponding Franck-Condon factors for systems with distorted Hamiltonian which arises in case of quadratic electron-phonon coupling which is significant in quantifying electronic dephasing. (C) 2012 Elsevier B. V. All rights reserved.

关键词： accuracy class Spectrography Closed-form solutions Franck-Condon factors ANNIHILATION OPERATORS Eigenvector time correlation functions

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Evaluation of reaction fluxes in stationary and oscillating far-from-equilibrium biological systems

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PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS 2015年 438卷 1-16页

作者： Bianca, C. Lemarchand, A. Univ Paris 06 Sorbonne Univ UMR 7600 Lab Phys Theor Mat Condensee F-75252 Paris 05 France CNRS UMR LPTMC 7600 Paris France

The complex spatio-temporal structures that appear in chemical and biological systems require far-from-equilibrium conditions which may lead to the circulation of reaction fluxes. We investigate how time asymmetry of cross-correlation functions of concentration fluctuations may be exploited to determine reaction fluxes at the cellular level. Using simulations of the master equation as a reference, we show that, far from a bifurcation, the Langevin approach provides a reliable tool to compute analytical expressions for time correlation functions. Biochemical mechanisms associated with bistability and oscillations issued from a Hopf bifurcation or a saddle-node infinite period bifurcation are considered. We show that the blind use of the simple relation obtained when assuming a linear deterministic dynamics often leads to a poor estimation of the value of the reaction flux and even of its sign. (C) 2015 Elsevier B.V. All rights reserved.

关键词： time correlation functions Reaction flux Hopf bifurcation Saddle-node bifurcation Langevin equations Master equation

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time correlations of coherent radiation propagating through a randomly inhomogeneous layer

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OPTICS AND SPECTROSCOPY 2008年第3期104卷 443-452页

作者： Kuz'min, V. L. Ul'yanov, D. S. St Petersburg Inst Trade & Econ St Petersburg 194021 Russia St Petersburg State Univ Fac Phys St Petersburg 198504 Russia

The intensity and the time correlation function of radiation transmitted through a layer of a randomly inhomogeneous medium are determined by numerical simulation of the Bethe-Salpeter equation for scalar and electromagnetic fields. The results of simulation agree well with the available experimental data. The domain of validity is determined numerically for the hypothesis of the diffusion approximation on the replacement of the extinction length by the transport length as a characteristic spatial scale for systems with the anisotropic scattering cross section. The polarized and depolarized components of the time correlation function of the transmitted light are calculated for the first time for different anisotropy parameters. It is shown that, to describe the residual polarization of transmitted light taking into account anisotropy, it is insufficient to perform the scale replacement of the extinction length by the transport length.

关键词： DISORDERED MEDIA LIGHT-SCATTERING BACKSCATTERING SPECTROSCOPY Light scattering Spectrography Anisotropy backscattering time correlation functions coherent radiation transmitted light Bethe-Salpeter equation

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