Unformatted text preview: is smaller than the
atom, shown in units of the recoil momentum hq, is ant
speed of sound in the condensate (position indicated by circle).
symmetric about v
0 as condensate atoms are Brag
Images are 3.3 3 3.3 mm.
scattered in either the forward or the backward directio
depending on the sign of v .
Both beams were derived from a common source, and
From these spectra, we determined the total line streng
then passed through two acousto-optical modulators opand the center frequency (Fig. 3) by ﬁtting the momentu
erated with the desired frequency difference v , giving the
transfer to the difference of two Gaussian line shapes, re
beams a detuning of 1.6 GHz below the jF
1 ! jF 0
resenting excitation in the forward and the backward dire
0, 1, 2 optical transitions. Thus, at the optical wavetion. Since S q
1 for free particles, we obtain the stat
length of 589 nm, the Bragg recoil velocity was hq m
structure factor as the ratio of the line strengths for th
7 mm s, giving a predicted Bragg resonance frequency of
trapped and the expanded atomic sa...
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- Fall '10
- Physics, Bose-Einstein condensation, Bogoliubov Theory, Bogoliubov quasiparticles