Radio-frequency spectroscopy of ultracold fermions.
Radio-frequency techniques were used to study ultracold fermions. We observed the absence of mean-field "clock" shifts, the dominant source of systematic error in current atomic clocks based on bosonic atoms. This absence is a direct consequence of fermionic antisymmetry. Resonance shifts proportional to interaction strengths were observed in a three-level system. However, in the strongly interacting regime, these shifts became very small, reflecting the quantum unitarity limit and many-body effects. This insight into an interacting Fermi gas is relevant for the quest to observe superfluidity in this system.
Gupta
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S
Department of Physics, Massachusetts Institute of Technology (MIT)-Harvard Center for Ultracold Atoms, and Research Laboratory of Electronics, MIT, Cambridge, MA 02139, USA. deep@mit.edu
Hadzibabic
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Zwierlein
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Stan
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Dieckmann
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Schunck
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Van Kempen
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Verhaar
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Ketterle
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