Browsing by Author "Chen, Y.P."

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    Extreme Tunability of Interactions in a Li7 Bose-Einstein Condensate
    (American Physical Society, 2009) Pollack, S.E.; Dries, D.; Junker, M.; Chen, Y.P.; Corcovilos, T.A.; Hulet, R.G.; Rice Quantum Institute
    We use a Feshbach resonance to tune the scattering length a of a Bose-Einstein condensate of Li7 in the |F=1,mF=1⟩ state. Using the spatial extent of the trapped condensate, we extract a over a range spanning 7 decades from small attractive interactions to extremely strong repulsive interactions. The shallow zero crossing in the wing of the Feshbach resonance enables the determination of a as small as 0.01 Bohr radii. Evidence of the weak anisotropic magnetic dipole interaction is obtained by comparison with different trap geometries for small a.
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    Photoassociation of a Bose-Einstein Condensate near a Feshbach Resonance
    (American Physical Society, 2008) Junker, M.; Dries, D.; Welford, C.; Hitchcock, J.; Chen, Y.P.; Hulet, R.G.; Rice Quantum Institute
    We measure the effect of a magnetic Feshbach resonance (FR) on the rate and light-induced frequency shift of a photoassociation resonance in ultracold Li7. The photoassociation-induced loss-rate coefficient Kp depends strongly on magnetic field, varying by more than a factor of 10?4 for fields near the FR. At sufficiently high laser intensities, Kp for a thermal gas decreases with increasing intensity, while saturation is observed for the first time in a Bose-Einstein condensate. The frequency shift is also strongly field dependent and exhibits an anomalous blueshift for fields just below the FR.