# Stuttgart 2012 – wissenschaftliches Programm

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# Q: Fachverband Quantenoptik und Photonik

## Q 22: Quantengase: Wechselwirkungseffekte 1

### Q 22.2: Vortrag

### Dienstag, 13. März 2012, 11:00–11:15, V7.03

**Faraday waves in elongated two-component Bose-Einstein condensates** — •Antun Balaž^{1} and Alexandru Nicolin^{2} — ^{1}Scientific Computing Laboratory, Institute of Physics Belgrade, University of Belgrade, Serbia — ^{2}Horia Hulubei National Institute for Physics and Nuclear Engineering, Department of Theoretical Physics, Bucharest, Romania

We show by extensive numerical simulations and analytical variational calculations that elongated binary non-miscible Bose-Einstein condensates subject to periodic
modulations of the radial confinement exhibit a Faraday instability similar to that seen in one-component condensates. Considering the
hyperfine states of ^{87}Rb condensates, we show that there are
two experimentally relevant stationary state configurations: the one in which the components
form a dark-bright symbiotic pair (the ground state of the system),
and the one in which the components are segregated (first excited state).
For each of these two configurations, we show numerically that far from
resonances the Faraday waves excited in the two components are
of similar periods, emerge simultaneously, and do not impact the dynamics
of the bulk of the condensate. We derive analytically the period of
the Faraday waves using a variational treatment of the coupled Gross-Pitaevskii
equations combined with a Mathieu-type analysis for the selection
mechanism of the excited waves. Finally, we show that for a modulation
frequency close to twice that of the radial trapping, the emergent
surface waves fade out in favor of a forceful collective mode that
turns the two condensate components miscible.