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Photon Fields (photon + field)

Distribution by Scientific Domains
Physics and Astronomy60%

Selected Abstracts

Theoretical study on quantum dynamics of bose system interacting with photon field

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 4 2001
Hidemi Nagao
Abstract We investigate the quantum dynamics of two-boson and two-level systems interacting with a one-mode photon field. The time evolution of the population for each state is calculated in terms of the Jaynes,Cummings model. We find the collapses and revivals of the order parameter for the Bose,Einstein condensation. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem 84: 401,408, 2001 [source]

Numerical simulations of photon trapping in doped photonic crystals doped with multi-level atoms

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 8 2005
Mahi R. Singh
Abstract A theory of photon trapping has been developed in photonic band-gap (PBG) and dispersive polaritonic band-gap (DPBG) materials doped with an ensemble of five-level atoms. These materials have gaps in their photon energy spectra. The atoms are prepared as coherent superpositions of the two lower states and interact with a reservoir and two photon fields. They also interact with each other by dipole-dipole interaction. The Schrödinger equation and the Laplace transform method are used to calculate the expressions for the number densities of the atomic states. Numerical simulations for a PBG material reveal that when the resonance energies lie away from the band edges and within the lower or upper bands, trapping is observed at certain values of the relative Rabi frequency associated with the two fields, which vary depending on the strength of the dipole-dipole interaction between the atoms. Also, if the photon fields are held constant, the population densities of the excited states of the atoms increase with increasing dipole-dipole interaction. These are very interesting phenomena. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Low-frequency line temperatures of the CMB (Cosmic Microwave Background)

ANNALEN DER PHYSIK, Issue 9 2009
R. Hofmann
Abstract Based on SU(2) Yang-Mills thermodynamics we interprete Aracde2's and the results of earlier radio-surveys on low-frequency cosmic microwave background (CMB) line temperatures as a phase-boundary effect. We explain the excess at low frequencies by evanescent, nonthermal photon fields of the CMB whose intensity is nulled by that of Planck distributed calibrator photons. The CMB baseline temperature thus is identified with the critical temperature of the deconfining-preconfining transition. [source]

Modelling the broad-band spectra of X-ray emitting GPS galaxies

ASTRONOMISCHE NACHRICHTEN, Issue 2-3 2009
L. Ostorero
Abstract The study of the broad-band emission of GHz-Peaked-Spectrum (GPS) radio galaxies is a powerful tool to investigate the physical processes taking place in the central, kpc-sized region of their active hosts, where the jets propagate and the lobes expand, interacting with the surrounding interstellar medium (ISM). We recently developed a new dynamical-radiative model to describe the evolution of the GPS phenomenon (Stawarz et al. 2008): as the relativistic jets propagate through the ISM, gradually engulfing narrow-line emitting gas clouds along their way, the electron population of the expanding lobes evolves, emitting synchrotron light, as well as inverse-Compton radiation via up-scattering of the photon fields from the host galaxy and its active nucleus. The model, which successfully reproduces the key features of the GPS radio sources as a class, provides a description of the evolution of their spectral energy distribution (SED) with the lobes' expansion, predicting significant and complex X-ray to , -ray emission. We apply here the model to the broad-band SED's of a sample of known, X-ray emitting GPS galaxies, and show that (i) the free-free absorption mechanism enables us to reproduce the radio continuum at frequencies below the turnover; (ii) the lobes' non-thermal, inverse-Compton emission can account for the observed X-ray spectra, providing a viable alternative to the thermal, accretion-dominated scenario. We also show that, in our sample, the relationship between the X-ray and radio hydrogen column densities, NH and NHI, is suggestive of a positive correlation, which, if confirmed, would support the scenario of high-energy emitting lobes (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]