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Claude Cohen Tannoudji

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

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Accueil du site > Thèses et habilitations > Towards quantum degenerate atomic Fermi mixtures : design of the experiment and magnetic transport of 6Li-40K

Towards quantum degenerate atomic Fermi mixtures : design of the experiment and magnetic transport of 6Li-40K

Soutenance de thèse de Thomas Salez (LKB)

Mardi 27 septembre 2011 à 11h en salle E244 , département de physique de l’ENS, 24 rue Lhomond 75005 Paris.

Abstract :

During my PhD, I participated in the full setup from scratch of an experiment that aims at cooling down and manipulating two fermionic alkaline atomic species, 6Li and 40K. Our goal is to study ultracold Fermi mixtures with mass imbalance, and to realize a quantum analog simulator. In fact, for certain quantum many-body problems, such as high critical temperature superconductivity and frustrated anti-ferromagnetism, there is no complete analytical or numerical solution. Therefore, cold atoms systems, due to their purity and their high degree of tunability, even on their interaction itself, offer a complementary and interesting point of view in the study of those phenomena.

As far as the experimental setup is concerned, we built an ultra-high vacuum system, a complete and stable laser source for each species, as well as two performing atomic sources, a 6Li Zeeman slower and a 40K bidimensionnal magneto-optical trap ; most of the optical and electrical quantities, as well as the imaging diagnostics, being computer controlled. Once those preliminary steps have been performed and optimized, we could obtain an efficient double magneto-optical trap, containing typically 5×109 atoms of 6Li and 8×109 atoms of 40K. In this configuration, we produced the first 6Li40K heteronuclear molecules by photo-association, for which we identified 70 rovibrational lines.

In a second part, I describe in detail the magnetic transport of the atomic mixture, between the magneto-optical trap chamber and a science cell, located in an ultra-high vacuum region with large optical access. The complete setup, from its design to its experimental implementation and optimization, as well as the development of useful numerical diagnostics, are parts of my work. The transport efficiency could be tested and optimized, allowing for a performing transfer of the mixture in the science cell.

Thus, after this thesis, all the experimental tools are operational in order to allow for evaporative cooling of the mixture in an optically plugged magnetic trap. Therefore, the field is open for quantum simulation and understanding of many-body problems in ultracold Fermi mixtures..

Voir en ligne : Thesis in pdf

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