S L Hemmer

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A strongly attractive, two-component Fermi gas of atoms exhibits universal behavior and should be mechanically stable as a consequence of the quantum-mechanical requirement of unitarity. This requirement limits the maximum attractive force to a value smaller than that of the outward Fermi pressure. To experimentally demonstrate this stability, we use(More)
We report on the observation of a highly degenerate, strongly interacting Fermi gas of atoms. Fermionic lithium-6 atoms in an optical trap are evaporatively cooled to degeneracy using a magnetic field to induce strong, resonant interactions. Upon abruptly releasing the cloud from the trap, the gas is observed to expand rapidly in the transverse direction(More)
We observe collective oscillations of a trapped, degenerate Fermi gas of 6Li atoms at a magnetic field just above a Feshbach resonance, where the two-body physics does not support a bound state. The gas exhibits a radial breathing mode at a frequency of 2837(05) Hz, in excellent agreement with the frequency of nu(H) identical with(More)
We measure a zero crossing in the scattering length of a mixture of the two lowest hyperfine states of 6 Li. To locate the zero crossing, we monitor the decrease in temperature and atom number arising from evaporation in a CO 2 laser trap as a function of magnetic field B. The temperature decrease and atom loss are minimized for Bϭ52.8Ϯ0.4 mT, consistent(More)
We derive the elastic collision rate for a harmonically trapped Fermi gas in the extreme unitarity limit where the s-wave scattering cross section is ␴(k)ϭ4␲/k 2 , with បk the relative momentum. The collision rate is given in the form ⌫ϭ␥ I(T/T F)—the product of a universal collision rate ␥ϭk B T F /(6␲ប) and a dimension-less function of the ratio of the(More)
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