Berlin 2001 – wissenschaftliches Programm
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AMPD: EPS AMPD
AMPD 4: Sitzung 4
AMPD 4.5: Vortrag
Dienstag, 3. April 2001, 15:00–15:25, H104
Sympathetic cooling of bosonic and fermionic Lithium gases to quantum degeneracy — •Florian Schreck1, Gabriele Ferrari2, Kristan Corwin1, Julien Cubizolles1, Lev Khaykovich1, and Christophe Salomon1 — 1Laboratoire Kastler Brossel, 24, rue Lhomond, 75005 Paris, France — 2LENS, European Laboratory for Non-Linear Spectroscopy, Universita di Firenze, Largo E. Fermi 2, 50125 Florence, Italy
Lithium atoms are interesting candidates for the study of degenerate gases of fermions, bosons, and their mixtures. The bosonic isotope 7Li possesses hyperfine ground states with both positive and negative scattering lengths, leading to stable and unstable condensates. Fermionic Lithium 6Li is a good candidate for the observation of a BCS transition.
We transfer a mixture of both Lithium isotopes from a magneto-optical trap to an electromagnetic Ioffe Pritchard trap with a radial oscillation frequency of 5 kHz. Due to suppression of the elastic scattering cross-section of 7Li at energies of 4 mK, we have to cool the atoms to 2 mK in order to start evaporation. This is done with Doppler cooling in the magnetic trap. Using forced evaporation of the 7Li gas, a sample of 1.3 105 6Li fermions has been sympathetically cooled to 9(3) µK, corresponding to 2.2(0.8) times the Fermi temperature. Cooling 7Li alone a phase space density exceeding 2.6 is reached with 5 104 atoms at 1.2 µK.