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Bulletin of the American Physical Society

Collective excitations of a resonantly interacting Fermi gas across the superfluid transition

Sascha Hoinka, Carlos Kuhn, James P. Denier, I. Herrera, Paul Dyke, Chris J. Vale, J. J. Kinnunen, Georg M. Bruun

Published Jun 1, 2018• 0 citations
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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.