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8 septembre 2017: 1 événement


  • Les séminaires en 2017 au LAC

    Vendredi 8 septembre 2017 11:00-12:00 - Marie BONNEAU - Technische Universität Wien

    Optimal Control of BECs for preparation of Strongly Correlated States (Marie BONNEAU)

    Résumé :
    Twin atom beams are the atomic analog of the twin photons generated through parametric down-conversion, which have been widely used in quantum optics. Twin atoms are emitted from a source Bose-Einstein condensate through an atomic four-wave mixing process, where the non-linearity is provided by the interatomic interactions. The geometry of the experiment sets the phase-matching conditions and therefore defines the signal and idler modes populated by the atoms. On the TU Wien setup, we explored two different geometries : In the first one, twin atoms are emitted in a single-well trapping potential, where only one pair of signal and idler modes is accessible. In the second, they are emitted in a double-well trapping potential, where two mode pairs are accessible and the twin atoms are expected to be entangled.

    We trap and manipulate the atoms with an atom chip, which consists of a surface with micro-fabricated structures generating magnetic fields. It permits implementing fast deformations of the potential in order to engineer the spatial wave function. Using quantum optimal control we determined the exact deformation sequence to be applied for transferring with high fidelity the source condensate from the ground state to a given excited eigenstate of the trapping potential.

    From this state, four-wave mixing occurs towards the lower eigenstates of the potential. The resulting twin atoms carry opposite momenta determined by the eigenstates energy difference.
    They are detected after time-of-flight expansion and their correlation properties are characterized.

    Lieu : Salle Balmer

    En savoir plus : Les séminaires en 2017 au LAC