Frankfurt 2006 – scientific programme
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Q: Quantenoptik und Photonik
Q 38: Quantengase IV
Q 38.1: Talk
Wednesday, March 15, 2006, 10:40–10:55, HVI
Excitation spectrum of an expanding BEC in 1D — •Antonio Negretti1,2 and Carsten Henkel3 — 1Dipartimento di Fisica, Universit∖‘a di Trento, Italy — 2ECT*, Villazzano, Italy — 3Institut f∖No-dqur Physik, Universit∖No-dqat Potsdam, Germany
We discuss the expansion of a Bose-Einstein condensate in a quasi-one-dimensional waveguide. The initial state is defined by a harmonic confinement, and the cloud expands along one direction after the aspect ratio of the confinement is suddenly changed. We compute for each time the excitation spectrum of the cloud and find that among the lowest modes, complex eigenfrequencies occur when the atom-atom interactions are sufficiently strong. This is interpreted in terms of a disruption of phase coherence due to a differential expansion velocity that exceeds the local speed of sound. A comparison to recent experiments with BECs expanding in 1D speckle potentials is made [1–3].
∖Zitat{1}{Cl∖’ement, Varon, Hugbart, Retter, Bouyer, Sanchez-Palencia, Gangardt, Shlyapnikov, Aspect: Phys. Rev. Lett. 95 (2005) 170409} ∖Zitat{2}{Fort, Fallani, Guarrera, Lye, Modugno, Wiersma, Inguscio: Phys. Rev. Lett. 95 (2005) 170410} ∖Zitat{3}{Schulte, Drenkelforth, Kruse, Ertmer, Arlt, Sacha, Zakrzewski, Lewenstein: Phys. Rev. Lett. 95 (2005) 170411}