Observation of dynamical instability for a Bose-Einstein condensate in a moving 1D optical lattice

• Published in: Physical review letters Vol. 93; no. 14; pp. 140406.1 - 140406.4
• Main Authors: FALLANI, L, DE SARLO, L, LYE, J. E, MODUGNO, M, SAERS, R, FORT, C, INGUSCIO, M
• Format: Journal Article
• Language: English
• Published: Ridge, NY American Physical Society 01-10-2004
• Subjects: Classical and quantum physics: mechanics and fields; Exact sciences and technology; Matter waves; Physics; Ultracold atom; Instability; Bose-Einstein condensation
• ISSN: 0031-9007; 1079-7114; 1079-7114
• DOI: 10.1103/physrevlett.93.140406

We have experimentally studied the unstable dynamics of a harmonically trapped Bose-Einstein condensate loaded into a 1D moving optical lattice. The lifetime of the condensate in such a potential exhibits a dramatic dependence on the quasimomentum state. This is unambiguously attributed to the onset of dynamical instability, after a comparison with the predictions of the Gross-Pitaevskii theory. Deeply in the unstable region we observe the rapid appearance of complex structures in the atomic density profile, as a consequence of the condensate phase uniformity breakdown.