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Accueil du site > Thèses et habilitations > Bose-Einstein condensation of chromium and study of inelastic collisions due to dipolar interactions

Bose-Einstein condensation of chromium and study of inelastic collisions due to dipolar interactions

Soutenance de thèse de Quentin Beaufilst (LPL)

Jeudi 29 octobre 2009, 14h, Amphi D de l’Université Paris 13, campus de Villetaneuse.

Abstract

Its large magnetic moment in the ground state makes chromium a good candidate for the study of dipolar interactions in a degenerate gas. We have built an experimental setup for trapping and cooling atoms of 52Cr down to Bose-Einstein condensation (BEC). Evaporative cooling takes place in a purely optical trap, which is loaded from the magneto-optical trap using a novel process of continuous accumulation of metastable states. We produce a condensate of typically 15 000 atoms in a time of 15 s.

We studied the possibility to bring all the Zeeman substates of a chromium BEC to degeneracy in a non-zero static magnetic field, using a radiofrequency (rf ) magnetic field, and demonstrated a new process of rf-assisted dipolar relaxation.

We also studied a narrow Feshbach resonance induced by dipolar interaction, which implies a d-wave collisional chanel. We analyzed this resonance in the presence of a rf magnetic field and we reinterpreted rf association of molecules as a mere Feshbach resonance between rf dressed states.

Finally, we have set up an optical lattice in the perspective of studying the effects of dipole-dipole interactions in reduced dimension.

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