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Collective excitations of a degenerate gas at the BEC-BCS crossover

M. Bartenstein·A. Altmeyer·S. Riedl·S. Jochim·C. Chin·J. Hecker Denschlag·R. Grimm
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Abstract

We study collective excitation modes of a fermionic gas of $^6$Li atoms in the BEC-BCS crossover regime. While measurements of the axial compression mode in the cigar-shaped trap close to a Feshbach resonance confirm theoretical expectations, the radial compression mode shows surprising features. In the strongly interacting molecular BEC regime we observe a negative frequency shift with increasing coupling strength. In the regime of a strongly interacting Fermi gas, an abrupt change in the collective excitation frequency occurs, which may be a signature for a transition from a superfluid to a collisionless phase.

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M. Bartenstein, A. Altmeyer, S. Riedl, S. Jochim, C. Chin, J. Hecker Denschlag, R. Grimm. 2004-05-09. Collective excitations of a degenerate gas at the BEC-BCS crossover. https://doi.org/10.1103/physrevlett.92.203201

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