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Manipulation cohérente d'atomes et de molécules diatomiques avec des impulsions mises en forme

Jérôme Degert 1
1 Femto (LCAR)
LCAR - Laboratoire Collisions Agrégats Réactivité
Abstract : This thesis deals with the theoretical and experimental study of coherent control of atomic and molecular systems with shaped pulses.
At first, we present several experiments of control of coherent transients in rubidium. These transients appear when a two-level system is excited by a perturbative chirped pulse, and are characterized by oscillations in the excited state population. For a strong chirp, we show that a phase step in the spectrum modifies the phase of the oscillations. Then, by direct analogy with Fresnel zone lens, we conceive à chirped pulse with a highly modulated amplitude, allowing to suppress destructive contributions to the population transfer.
In a second set of experiments, we focus on quantum path interferences in two-photon transitions excited by linearly chirped pulses. Owing to the broad bandwidth of ultrashort pulses, sequential and direct excitation paths contribute to the excited state population. Oscillations resulting from interferences between these two paths are observed in atomic sodium. Moreover, we show that they are observable whatever the sign of chirp.
Theoretically, we study the control of the predissociation of a benchmark diatomic molecule: NaI. Predissociation leads to matter wave interferences in the fragments distribution. First, we show that a suitably chosen probe pulse allows the observation of theses interferences. Next, using a sequence of control pulse inducing electronic transition, we demonstrate the possibility to manipulate fragment energy distribution.
Complete list of metadatas

https://tel.archives-ouvertes.fr/tel-00288584
Contributor : Jérôme Degert <>
Submitted on : Tuesday, June 17, 2008 - 3:26:59 PM
Last modification on : Friday, February 28, 2020 - 1:52:03 PM
Long-term archiving on: : Friday, September 28, 2012 - 4:15:13 PM

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  • HAL Id : tel-00288584, version 1

Citation

Jérôme Degert. Manipulation cohérente d'atomes et de molécules diatomiques avec des impulsions mises en forme. Physique Atomique [physics.atom-ph]. Université Paul Sabatier - Toulouse III, 2002. Français. ⟨tel-00288584⟩

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