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Quasi-2D Fermi Gases

Paul Dyke

Centre for Atom Optics and Ultrafast Spectroscopy,Swinburne University of Technology

4:00 pm Friday, 26 March 2010,
EN413 (EN Building), Hawthorn.

Quasi-2D degenerate Fermi gases provide a rich physical environment where new phenomena emerge that do not occur in 3D. This talk describes the first experiments on a quasi-2D Fermi gas across the broad 6Li Feshbach resonance at 834 G. We present the observation of crossing from a 3D gas to a 2D gas where the transition occurs at ~2000 atoms agreeing within experimental uncertainty with the ideal gas crossover. The observations are made through measuring the radial and axial widths of the gas at three different magnetic fields, 810 G, 834 G, and 991 G. At 991 G we find good experimental agreement with the non-interacting theory. We also observe a change in the aspect ratio as we approach the 2D regime which is not present in our 3D single beam optical dipole trap and is absent in any 3D system. These first results indicate that we have a quasi-2D Fermi gas.

The main experimental result is the observation of a confinement induced resonance (CIR) through measurement of the release energy of the cloud in the tightly confined direction. We observe a significant deviation from the 3D case, consistent with a CIR. The CIR appears when the 3D scattering length approaches the transverse harmonic oscillator length. For our experimental parameters this occurs at a magnetic field of 819(1) G.

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