635 research outputs found
Kicked-rotor quantum resonances in position space: Application to situations of experimental interest
In this work we apply the formalism developed in [M. Lepers \emph{et al}.,
Phys. Rev. A \textbf{77}, 043628 (2008)] to different initial conditions
corresponding to systems usually met in real-life experiments, and calculate
the observable quantities that can be used to characterize the dynamics of the
system. The position space point of view allows highly intuitive pictures of
the physics at play.Comment: accepted in Eur. Phys. J.
Calculation of transition probabilities and ac Stark shifts in two-photon laser transitions of antiprotonic helium
Numerical ab initio variational calculations of the transition probabilities
and ac Stark shifts in two-photon transitions of antiprotonic helium atoms
driven by two counter-propagating laser beams are presented. We found that
sub-Doppler spectroscopy is in principle possible by exciting transitions of
the type (n,L)->(n-2,L-2) between antiprotonic states of principal and angular
momentum quantum numbers n~L-1~35, first by using highly monochromatic,
nanosecond laser beams of intensities 10^4-10^5 W/cm^2, and then by tuning the
virtual intermediate state close (e.g., within 10-20 GHz) to the real state
(n-1,L-1) to enhance the nonlinear transition probability. We expect that ac
Stark shifts of a few MHz or more will become an important source of systematic
error at fractional precisions of better than a few parts in 10^9. These shifts
can in principle be minimized and even canceled by selecting an optimum
combination of laser intensities and frequencies. We simulated the resonance
profiles of some two-photon transitions in the regions n=30-40 of the
\bar{p}^4He^+ and \bar{p} ^3He^+ isotopes to find the best conditions that
would allow this.Comment: 18 pages 2 tables 12 figures, submitted to Phys. Rev.
Quantum coherence generated by interference-induced state selectiveness
The relations between quantum coherence and quantum interference are
discussed. A general method for generation of quantum coherence through
interference-induced state selection is introduced and then applied to `simple'
atomic systems under two-photon transitions, with applications in quantum
optics and laser cooling.Comment: 17 pages, 7 figures, to be published in Journal of Modern Optics'
special issue on quantum interferenc
Self-similarities in the frequency-amplitude space of a loss-modulated CO laser
We show the standard two-level continuous-time model of loss-modulated CO
lasers to display the same regular network of self-similar stability islands
known so far to be typically present only in discrete-time models based on
mappings. For class B laser models our results suggest that, more than just
convenient surrogates, discrete mappings in fact could be isomorphic to
continuous flows.Comment: (5 low-res color figs; for ALL figures high-res PDF:
http://www.if.ufrgs.br/~jgallas/jg_papers.html
Nonprobabilistic teleportation of field state via cavity QED
In this article we discuss a teleportation scheme of coherent states of
cavity field. The experimental realization proposed makes use of cavity quatum
electrodynamics involving the interaction of Rydberg atoms with micromaser and
Ramsey cavities. In our scheme the Ramsey cavities and the atoms play the role
of auxiliary systems used to teleport the state from a micromaser cavity to
another. We show that, even if the correct atomic detection fails in the first
trials, one can succeed in teleportating the cavity field state if the proper
measurement occurs in a later atom
Sensitivity to the initial state of interacting ultracold bosons in disordered lattices
We study the dynamics of a nonlinear one-dimensional disordered system
obtained by coupling the Anderson model with the Gross-Pitaevskii equation. An
analytical model provides us with a single quantity globally characterizing the
localization of the system. This quantity obeys a scaling law with respect to
the width of the initial state, which can be used to characterize the dynamics
independently of the initial state.Comment: 10 pages, 12 figures, revtex4, submited to PR
Electroabsorption modulator laser for cost-effective 40 Gbit/s networks with low drive voltage, chirp and temperature dependence
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