Excitation Spectrum of a Bose-Einstein Condensate
Jeff SteinhauerDepartment of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, IsraelRoee OzeriDepartment of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, IsraelNadav KatzDepartment of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, IsraelNir DavidsonDepartment of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
2002en
ABI
Abstract
We report a measurement of the excitation spectrum omega(k) and the static structure factor S(k) of a Bose-Einstein condensate. The excitation spectrum displays a linear phonon regime, as well as a parabolic single-particle regime. The linear regime provides an upper limit for the superfluid critical velocity, by the Landau criterion. The excitation spectrum agrees well with the Bogoliubov spectrum in the local density approximation, even close to the long-wavelength limit of the region of applicability. Feynman's relation between omega(k) and S(k) is verified, within an overall constant.
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