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Claude Cohen Tannoudji

Prix Nobel en 1997 pour le ralentissement et le piégeage des atomes par la lumière laser.

Ses travaux sont à la source des recherches actuelles de l'IFRAF.




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Accueil du site > Thèses et habilitations > Bose-Einstein condensate in a dressed trap : collective modes in a two-dimensional superfluid

Bose-Einstein condensate in a dressed trap : collective modes in a two-dimensional superfluid

Thesis Defense of Karina Merloti (LPL)

Wednesday, December 11th, 2013 at 10:00 Amphi. C - Institut Galilée. Université Paris 13 - Institut Galilée 99, av. J.B. Clément - 93430 Villetaneuse France

This thesis presents the production of a degenerate rubidium 87 gas in the quasi two-dimensional (2D) regime and the study of collective modes of this gas. We show that the gas can be prepared below the Berezinskii-Kosterlitz-Thouless transition threshold. The superfluid nature of the gas is demonstrated through the observation of the quadrupole and scissors modes. We measure their oscillation frequencies. The bidimensional character of the gas is evidenced through the measurement of the monopole mode frequency. We show the influence of the third, hidden, dimension on this oscillation frequency.

In order to produce the superfluid, a Bose-Einstein condensate is first produced in a magnetic quadrupole trap plugged by a far off-resonance laser beam, carefully optimized to overcome Majorana spin flip losses. The condensate is then transferred to the « dressed trap », i.e. the adiabatic potential seen by the radiofrequency dressed atoms. We ramp up the magnetic gradient to its maximum value in order to increase the trap anisotropy, and eventually reach the quasi-2D regime for the Bose gas. The two kinds of trap used are characterized in detail. We take advantage of the adiabatic potential smoothness in order to excite and study the collective modes.

Board of examiners

Thomas Bourdel, Laboratoire Charles Fabry, Institut d’Optique, Referee
Thorsten Schumm, Institute of Atomic and Subatomic Physics, Vienna University of Technology, Referee
Aidan Arnold, Photonics Group, University of Strathclyde
David Guéry-Odelin, Laboratoire de Collisions - Agrégats - Réactivité, Université Paul Sabatier
Bruno Manil, LPL, Université Paris 13
Hélène Perrin, LPL, Université Paris 13, Thesis Director

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