1,531 research outputs found
Multiple Ionization under Strong XUV to X-ray Radiation
We review the main aspects of multiple photoionization processes in atoms
exposed to intense, short wavelength radiation. The main focus is the
theoretical framework for the description of such processes as well as the
conditions under which direct multiphoton multiple ionization processes can
dominate over the sequential ones. We discuss in detail the mechanisms
available in different wavelength ranges from the infrared to the hard X-rays.
The effect of field fluctuations, present at this stage in all SASE
free-electron-laser (FEL) facilities, as well as the effect of the interaction
volume integration, are also discussed
Basis-dependent dynamics of trapped Bose-Einstein condensates and analogies with semi-classical laser theory
We present a consistent second order perturbation theory for the lowest-lying
condensed modes of very small, weakly-interacting Bose-Einstein condensates in
terms of bare particle eigenstates in a harmonic trap. After presenting our
general approach, we focus on explicit expressions for a simple three-level
system, mainly in order to discuss the analogy of a single condensate occupying
two modes of a trap with the semi-classical theory for two-mode photon lasers.
A subsequent renormalization of the single-particle energies to include the
dressing imposed by mean fields demonstrates clearly the consistency of our
treatment with other kinetic approaches.Comment: 2 Modified Sections: (i) Analogy between 2-mode BEC and
Semi-classical laser theory (ii) Links to other kinetic theories made more
explicit. European Physical Journal D (accepted for publication): Laser
Cooling and Quantum Gas Sectio
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