Browsing by Author "Strecker, K.E."

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    Bright matter wave solitons in Bose–Einstein condensates
    (IOP Publishing, 2003) Strecker, K.E.; Partridge, G.B.; Truscott, A.G.; Hulet, R.G.; Rice Quantum Institute
    We review recent experimental and theoretical work on the creation of bright matter wave solitons in Bose–Einstein condensates. In two recent experiments, solitons are formed from Bose–Einstein condensates of  7Li by utilizing a Feshbach resonance to switch from repulsive to attractive interactions. The solitons are made to propagate in a one-dimensional potential formed by a focused laser beam. For repulsive interactions, the wavepacket undergoes dispersive wavepacket spreading, while for attractive interactions, localized solitons are formed. In our experiment, a multi-soliton train containing up to ten solitons is observed to propagate without spreading for a duration of 2 s. Adjacent solitons are found to interact repulsively, in agreement with a calculation based on the nonlinear Schrödinger equation assuming that the soliton train is formed with an alternating phase structure. The origin of this phase structure is not entirely clear.
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    Bright Soliton Trains of Trapped Bose-Einstein Condensates
    (American Physical Society, 2002) Khawaja, U. Al; Stoof, H.T.C.; Hulet, R.G.; Strecker, K.E.; Partridge, G.B.; Rice Quantum Institute
    We variationally determine the dynamics of bright soliton trains composed of harmonically trapped Bose-Einstein condensates with attractive interatomic interactions. In particular, we obtain the interaction potential between two solitons. We also discuss the formation of soliton trains due to the quantum mechanical phase fluctuations of a one-dimensional condensate.
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    Laser-free slow atom source
    (American Physical Society, 1999) Ghaffari, B.; Gerton, J.M.; McAlexander, W.I.; Strecker, K.E.; Homan, D.M.; Hulet, R.G.; Rice Quantum Institute
    A slow atom source, which does not rely on lasers, has been developed and characterized. The device, acting as an atomic low-pass velocity filter, utilizes permanent magnets to passively select the slow atoms present in a thermal atomic beam. Slow atoms are guided along a curved, conduction-limited tube by an octupole magnetic field, while fast atoms, unable to follow the curved trajectory, strike the tube wall and are removed from the beam. The performance of the device is demonstrated by loading a magneto-optical trap. Approximately 2×108 lithium atoms are loaded with a rate of ∼6×106 atoms/s, while maintaining a background gas pressure of ∼10−11 torr. This loading technique provides an exceptionally simple, economical, and robust alternative to laser cooling methods.
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    Molecular Probe of Pairing in the BEC-BCS Crossover
    (American Physical Society, 2005) Partridge, G.B.; Strecker, K.E.; Kamar, R.I.; Jack, M.W.; Hulet, R.G.; Rice Quantum Institute
    We have used optical molecular spectroscopy to probe the many-body state of paired L6i atoms near a broad Feshbach resonance. The optical probe projects pairs of atoms onto a vibrational level of an excited molecule. The rate of excitation enables a precise measurement of the closed-channel contribution to the paired state. This contribution is found to be quite small, supporting the concept of universality for the description of broad Feshbach resonances. The dynamics of the excitation provide clear evidence for pairing across the BEC-BCS crossover and into the weakly interacting BCS regime.