740 research outputs found
Pairing without Superfluidity: The Ground State of an Imbalanced Fermi Mixture
Radio-frequency spectroscopy is used to study pairing in the normal and
superfluid phases of a strongly interacting Fermi gas with imbalanced spin
populations. At high spin imbalances the system does not become superfluid even
at zero temperature. In this normal phase full pairing of the minority atoms is
observed. This demonstrates that mismatched Fermi surfaces do not prevent
pairing but can quench the superfluid state, thus realizing a system of fermion
pairs that do not condense even at the lowest temperature
Observation of Feshbach resonances between two different atomic species
We have observed three Feshbach resonances in collisions between lithium-6
and sodium-23 atoms. The resonances were identified as narrow loss features
when the magnetic field was varied. The molecular states causing these
resonances have been identified, and additional lithium-sodium resonances are
predicted. These resonances will allow the study of degenerate Bose-Fermi
mixtures with adjustable interactions, and could be used to generate ultracold
heteronuclear molecules
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