5,159 research outputs found
Perturbative evolution of far off-resonance driven two-level systems: Coherent population trapping, localization, and harmonic generation
The time evolution of driven two-level systems in the far off-resonance
regime is studied analytically. We obtain a general first-order perturbative
expression for the time-dependent density operator which is applicable
regardless of the coupling strength value. In the strong field regime, our
perturbative expansion remains valid even when the far off-resonance condition
is not fulfilled. We find that, in the absence of dissipation, driven two-level
systems exhibit coherent population trapping in a certain region of parameter
space, a property which, in the particular case of a symmetric double-well
potential, implies the well-known localization of the system in one of the two
wells. Finally, we show how the high-order harmonic generation that this kind
of systems display can be obtained as a straightforward application of our
formulation.Comment: 14 pages, LaTeX, 2 figures, acknowledgments adde
The Grid[Way] Job Template Manager, a tool for parameter sweeping
Parameter sweeping is a widely used algorithmic technique in computational
science. It is specially suited for high-throughput computing since the jobs
evaluating the parameter space are loosely coupled or independent.
A tool that integrates the modeling of a parameter study with the control of
jobs in a distributed architecture is presented. The main task is to facilitate
the creation and deletion of job templates, which are the elements describing
the jobs to be run. Extra functionality relies upon the GridWay Metascheduler,
acting as the middleware layer for job submission and control. It supports
interesting features like multi-dimensional sweeping space, wildcarding of
parameters, functional evaluation of ranges, value-skipping and job template
automatic indexation.
The use of this tool increases the reliability of the parameter sweep study
thanks to the systematic bookkeping of job templates and respective job
statuses. Furthermore, it simplifies the porting of the target application to
the grid reducing the required amount of time and effort.Comment: 26 pages, 1 figure
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