40 research outputs found
Radiative energy shifts of accelerated atoms
We consider the influence of acceleration on the radiative energy shifts of
atoms in Minkowski space. We study a two-level atom coupled to a scalar quantum
field. Using a Heisenberg picture approach, we are able to separate the
contributions of vacuum fluctuations and radiation reaction to the Lamb shift
of the two-level atom. The resulting energy shifts for the special case of a
uniformly accelerated atom are then compared with those of an atom at rest.Comment: 12 pages, Latex, 1 figure as uuencoded eps file, shorter version will
appear in Phys. Rev.
Spontaneous excitation of an accelerated atom: The contributions of vacuum fluctuations and radiation reaction
We consider an atom in interaction with a massless scalar quantum field. We
discuss the structure of the rate of variation of the atomic energy for an
arbitrary stationary motion of the atom through the quantum vacuum. Our main
intention is to identify and to analyze quantitatively the distinct
contributions of vacuum fluctuations and radiation reaction to the spontaneous
excitation of a uniformly accelerated atom in its ground state. This gives an
understanding of the role of the different physical processes underlying the
Unruh effect. The atom's evolution into equilibrium and the Einstein
coefficients for spontaneous excitation and spontaneous emission are
calculated.Comment: 13 pages, KONS-RGKU-94-09, to appear in Phys. Rev.
Quantum field theory of cooperative atom response: Low light intensity
We study the interactions of a possibly dense and/or quantum degenerate gas
with driving light. Both the atoms and the electromagnetic fields are
represented by quantum fields throughout the analysis. We introduce a field
theory version of Markov and Born approximations for the interactions of light
with matter, and devise a procedure whereby certain types of products of atom
and light fields may be put to a desired, essentially normal, order. In the
limit of low light intensity we find a hierarchy of equations of motion for
correlation functions that contain one excited-atom field and one, two, three,
etc., ground state atom fields. It is conjectured that the entire linear
hierarchy may be solved by solving numerically the classical equations for the
coupled system of electromagnetic fields and charged harmonic oscillators. We
discuss the emergence of resonant dipole-dipole interactions and collective
linewidths, and delineate the limits of validity of the column density approach
in terms of non-cooperative atoms by presenting a mathematical example in which
this approach is exact.Comment: 35 pages, RevTe
Cavity-QED tests of representations of canonical commutation relations employed in field quantization
Various aspects of dissipative and nondissipative decoherence of Rabi
oscillations are discussed in the context of field quantization in alternative
representations of CCR. Theory is confronted with experiment, and a possibility
of more conclusive tests is analyzed.Comment: Discussion of dissipative and nondissipative decoherence is included.
Theory is now consistent with the existing data and predictions for new
experiments are more reliabl
INVERSE SCATTERING TRANSFORM ANALYSIS OF STOKES-ANTI-STOKES STIMULATED RAMAN SCATTERING
Zakharov-Shabat--Ablowitz-Kaup-Newel-Segur representation for
Stokes-anti-Stokes stimulated Raman scattering is proposed. Periodical waves,
solitons and self-similarity solutions are derived. Transient and bright
threshold solitons are discussed.Comment: 16 pages, LaTeX, no figure
Spontaneous emission and level shifts in absorbing disordered dielectrics and dense atomic gases: A Green's function approach
Spontaneous emission and Lamb shift of atoms in absorbing dielectrics are
discussed. A Green's-function approach is used based on the multipolar
interaction Hamiltonian of a collection of atomic dipoles with the quantised
radiation field. The rate of decay and level shifts are determined by the
retarded Green's-function of the interacting electric displacement field, which
is calculated from a Dyson equation describing multiple scattering. The
positions of the atomic dipoles forming the dielectrics are assumed to be
uncorrelated and a continuum approximation is used. The associated unphysical
interactions between different atoms at the same location is eliminated by
removing the point-interaction term from the free-space Green's-function (local
field correction). For the case of an atom in a purely dispersive medium the
spontaneous emission rate is altered by the well-known Lorentz local-field
factor. In the presence of absorption a result different from previously
suggested expressions is found and nearest-neighbour interactions are shown to
be important.Comment: 6 pages no figure
Problem of Resonance Fluorescence and the Inadequacy of Spontaneous Emission as a Test of Quantum Electrodynamics
Nonlocal Reductions of The Multicomponent Nonlinear Schrödinger Equation on Symmetric Spaces
Our aim is to develop the inverse scattering transform for multicomponent generalizations of nonlocal reductions of the nonlinear Schrödinger (NLS) equation with PT symmetry related to symmetric spaces. This includes the spectral properties of the associated Lax operator, the Jost function, the scattering matrix, the minimum set of scattering data, and the fundamental analytic solutions. As main examples, we use theManakov vector Schrödinger equation (related to A.III-symmetric spaces) and the multicomponent NLS (MNLS) equations of Kulish–Sklyanin type (related to BD.I-symmetric spaces). Furthermore, we obtain one- and two-soliton solutions using an appropriate modification of the Zakharov–Shabat dressing method. We show that the MNLS equations of these types admit both regular and singular soliton configurations. Finally, we present different examples of one- and two-soliton solutions for both types of models, subject to different reductions