Probing the Excitation Spectrum of a Fermi Gas in the BCS-BEC Crossover Regime

M. Greiner, C. A. Regal, and D. S. Jin

Phys. Rev. Lett. 94, 070403 – Published 24 February 2005

Abstract

We measure excitation spectra of an ultracold gas of fermionic ${}^{40}K$ atoms in the BCS–Bose-Einstein-condensation (BEC) crossover regime. The measurements are performed with a novel spectroscopy that employs a small modulation of the $B$ field close to a Feshbach resonance to give rise to a modulation of the interaction strength. With this method we observe both a collective excitation as well as the dissociation of fermionic atom pairs in the strongly interacting regime. The excitation spectra reveal the binding energy or excitation gap for pairs in the crossover region.

Received 12 July 2004

DOI:https://doi.org/10.1103/PhysRevLett.94.070403

Authors & Affiliations

M. Greiner^*, C. A. Regal, and D. S. Jin^†

JILA, National Institute of Standards and Technology and University of Colorado, and Department of Physics, University of Colorado, Boulder, Colorado 80309-0440, USA

^*Email address: markus.greiner@colorado.edu Electronic address: http://jilawww.colorado.edu/~jin/
^†Quantum Physics Division, National Institute of Standards and Technology.

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Vol. 94, Iss. 7 — 25 February 2005

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