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Atomic Systems (atomic + system)

Distribution by Scientific Domains

Physics and Astronomy	58%
Chemistry	41%

Selected Abstracts

Soliton propagation in an absorbing three-level atomic system

LASER PHYSICS LETTERS, Issue 8 2004
H. Eleuch
Abstract We present analytic results of soliton shapes propagating in an absorbing three-level atomic system in the lambda configuration which is excited by a CWfield at the Stokes transition. We find analytic relations for the control of the propagation velocity which can be influenced by the pulse width and by the intensity and polarization of the CW field. (© 2004 by ASTRO, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

Effects of decay-induced coherence and microwaveinducedcoherence on the index of refraction in a three-level , -type atomic system

LASER PHYSICS LETTERS, Issue 4 2004
Wei-Hua Xu
Abstract We study the dispersion-absorption properties in a three-level , -type atomic system with two closely lying lower levels. We consider two schemes: in the first, the two lower levels are coupled by decay-induced coherence, and in the second, quantum coherence is created by coupling the two lower levels to each other by a microwave field. We found that due to the decay-induced coherence or microwave-induced coherence, the dispersion-absorption properties can be controlled by the relative phase of applied fields, large index of refraction without absorption always can be obtained just by choosing proper values of the (© 2004 by ASTRO, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

Correlation studies in weakly confining quantum dot potentials

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 15 2008
Peter Kimani
Abstract We investigate the electron correlation in few-electron closed-shell atomic systems and similarly in few-electron quantum dots under weak confinement. As usual we start with restricted Hartree,Fock (HF) calculations and add electron correlation in steps in a series of approximations based on the single particle Green's function approach: (i) second-order Green function (GF); (ii) 2ph -Tamm-Dancoff approximation (TDA); and (iii) an extended version thereof which introduces ground-state correlation into the TDA. Our studies exhibit similarities and differences between weakly confined quantum dots and standard atomic systems. The calculations support the application of HF, GF, and TDA techniques in the modeling of three-dimensional quantum dot systems. The observed differences emphasize the significance of confinement and electronic features unique to quantum dots, such as the increased binding of electrons with higher angular momentum and thus,compared to atomic systems,modified shell-filling sequences. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 [source]

Erratum: Vikas, B. M. Deb: Ground-state electronic energies and densities of atomic systems in strong magnetic fields through a time-dependent hydrodynamical equation

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 4 2008
B. M. Deb
No abstract is available for this article. [source]

Systematic formulations for electronegativity and hardness and their atomic scales within density functional softness theory

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 2 2006
Mihai V. Putz
Abstract A unified Mulliken valence with Parr ground-state electronegativity picture is presented. It provides a useful analytical tool on which the absolute hardness as well ionization potential and electron affinity functionals are based. For all these chemical reactivity indices, systematic approximate density functionals are formulated within density functional softness theory and are applied to atomic systems. For the absolute hardness, a special relationship with the new electronegativity ansatz and a particular atomic trend paralleling the absolute electron affinity are established that should complement and augment the earlier finite-difference energetic approach. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source]

Coherent bichromatic spectroscopy of Rb vapor with a femtosecond laser

JOURNAL OF RAMAN SPECTROSCOPY, Issue 6 2006
A. V. Akimov
Abstract We experimentally studied the narrow resonances of coherent population trapping (CPT) in a rubidium vapor cell with the help of a phase-coherent bichromatic light source based on a mode-locked femtosecond laser. We investigated the dependence of the contrast and the width of CPT resonance on the light power, as well as the sensitivity of the shape of the resonance to a magnetic field. Prospects of using the novel bichromatic source for phase-coherent Raman spectroscopy of CPT resonances in atomic systems with a large energy separation of the lower levels are discussed. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Photon statistics of a single quantum dot in a microcavity

PHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 10 2010
Yumian Su
Abstract We introduce a theoretical model to describe the dynamics of an electrically pumped single quantum dot interacting with a microcavity. Within our framework, it is possible to study the full photon statistics of the quantum light emission for different pump rates and to include semiconductor specific Pauli- blocking effects in the polarization dynamics. In the single photon limit, we find that, compared to comparable atomic systems, two photon events are suppressed stronger by the carrier reservoir of the quantum dot. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Low intensity directional switching of light in semiconductor microcavities

PHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 1 2009
Stefan Schumacher
Abstract Recently it was demonstrated that in atomic vapors weak control beams can manipulate (or switch) the propagation direction of strong light beams [Dawes et al., Science 308, 672 (2005)]. As a semiconductor analog of such all-optical switching, we present a proposal for similar manipulation and switching in planar semiconductor microcavities. Using a microscopic many-particle theory, we investigate the spatio-temporal dynamics of four-wave mixing signals and related instabilities in these systems. Even though the underlying physical processes are different from atomic systems, we find that microcavities allow for reversible directional manipulation of light. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Spontaneous emission of light from atoms: the model

ANNALEN DER PHYSIK, Issue 7 2005
P. Marecki
Abstract We investigate (non-relativistic) atomic systems interacting with quantum electromagnetic field (QEF). The resulting model describes spontaneous emission of light from a two-level atom surrounded by various initial states of the QEF. We assume that the quantum field interacts with the atom via the standard, minimal-coupling Hamiltonian, with the A2 term neglected. We also assume that there will appear at most single excitations (photons). By conducting the analysis on a general level we allow for an arbitrary initial state of the QEF (which can be for instance: the vacuum, the ground state in a cavity, or the squeezed state). We derive a Volterra-type equation which governs the time evolution of the amplitude of the excited state. The two-point function of the initial state of the QEF, integrated with a combination of atomic wavefunctions, forms the kernel of this equation. [source]