117 research outputs found
Decoherence of Atomic Gases in Largely Detuned Laser Fields
We study theoretically the decoherence of a gas of bosonic atoms induced by
the interaction with a largely detuned laser beam. It is shown that for a
standing laser beam decoherence coincides with the single-particle result. For
a running laser beam many-particle effects lead to significant modifications.Comment: 5 pages, 2 Figures, RevTe
Creation of Skyrmions in a Spinor Bose-Einstein Condensate
We propose a scheme for the creation of skyrmions (coreless vortices) in a
Bose-Einstein condensate with hyperfine spin F=1. In this scheme, four
traveling-wave laser beams, with Gaussian or Laguerre-Gaussian transverse
profiles, induce Raman transitions with an anomalous dependence on the laser
polarization, thereby generating the optical potential required for producing
skyrmions.Comment: 5 pages, 2 figures, RevTe
Topological Coherent Modes in Trapped Bose Gas
The report reviews the problem of topological coherent modes, which are
nonlinear collective states of Bose-condensed atoms. Such modes can be
generated by means of alternating external fields, whose frequencies are in
resonance with the transition frequencies between the related modes. The Bose
gas with generated topological coherent modes is a collective nonlinear analog
of a resonant atom. Such systems exhibit a variety of nontrivial effects, e.g.:
interference fringes, interference current, mode locking, dynamic transitions,
critical phenomena, chaotic motion, harmonic generation, parametric conversion,
atomic squeezing, and entanglement production.Comment: 10 pages, Latex file; Plenary Talk, International Conference on
Atomic Physics, Rio de Janeir
Photons as quasi-charged particles
The Schrodinger motion of a charged quantum particle in an electromagnetic
potential can be simulated by the paraxial dynamics of photons propagating
through a spatially inhomogeneous medium. The inhomogeneity induces geometric
effects that generate an artificial vector potential to which signal photons
are coupled. This phenomenon can be implemented with slow light propagating
through an a gas of double-Lambda atoms in an electromagnetically-induced
transparency setting with spatially varied control fields. It can lead to a
reduced dispersion of signal photons and a topological phase shift of
Aharonov-Bohm type
Interference scheme to measure light-induced nonlinearities in Bose-Einstein condensates
Light-induced nonlinear terms in the Gross-Pitaevskii equation arise from the
stimulated coherent exchange of photons between two atoms. For atoms in an
optical dipole trap this effect depends on the spatial profile of the trapping
laser beam. Two different laser beams can induce the same trapping potential
but very different nonlinearities. We propose a scheme to measure light-induced
nonlinearities which is based on this observation.Comment: 2 figure
- …