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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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Bragg Spectroscopy of Unitary Fermi Gas

Séminaire de Peter Hannaford (Melbourne, Australia)

Vendredi 24 juin 2011, 9h15, salle de réunion de l’IFRAF, au 4e etage du batiment Rataud, Ecole normale supérieure, 45rue d’Ulm 75005 Paris.


We will describe the application of Bragg spectroscopy to the study of pair correlations in a balanced spin mixture of an ultracold Fermi gas of lithium-6 atoms confined in an optical dipole trap. Pair correlations are studied as the system is tuned, via a Feshbach resonance, from a BEC of bosonic lithium-6 dimers to a unitary gas of strongly interacting fermions to a fermonic BCS superfluid. Bragg spectra taken close to unitarity show that short-range pair correlations in the strongly interacting Fermi gas remarkably follow a simple universal law described by Tan’s relations based on just a single short-range parameter,the `contact’, over a broad range of relative momenta k/kF and interaction strengths 1/(kFa).

Bragg spectra taken at unitarity over a range of temperatures indicate that the contact, and hence the short-range pair correlations, persist at temperatures well above the superfluid transition temperature, in good agreement with recent theoretical calculations.

Finally, we will report on results for the crossover from three to two dimensions for a weakly interacting Fermi gas of lithium-6 atoms confined in a single `pancake’ dipole trap.

Peter Hannaford, ARC Centre for Quantum-Atom Optics (ACQAO), Swinburne University of Technology, Melbourne, Australia.