# Heidelberg 2015 – wissenschaftliches Programm

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# A: Fachverband Atomphysik

## A 23: Ultra-cold atoms, ions and BEC IV (with Q)

### A 23.3: Vortrag

### Mittwoch, 25. März 2015, 15:00–15:15, C/HSW

**Stability and Tunneling Dynamics of a Dark-Bright Soliton Pair in a Harmonic Trap** — •Evangelos T. Karamatskos^{1}, Jan Stockhofe^{1}, Panayotis G. Kevrekidis^{2,3}, and Peter Schmelcher^{1,4} — ^{1}Zentrum für Optische Quantentechnologien, Universität Hamburg — ^{2}University of Massachusetts, Amherst, USA — ^{3}Los Alamos National Laboratory, USA — ^{4}The Hamburg Centre for Ultrafast Imaging

We consider a binary repulsive Bose-Einstein condensate in a harmonic trap in one spatial dimension and investigate particular solutions consisting of two dark-bright solitons. There are two different stationary solutions characterized by the phase difference in the bright component, in-phase and out-of-phase states. We show that above a critical particle number in the bright component, a symmetry breaking bifurcation of the pitchfork type occurs that leads to a new asymmetric solution. These three different states support different small amplitude oscillations, characterized by an almost stationary density of the dark component and a tunneling of the bright component between the two dark solitons. Within a suitable effective double-well picture, these can be understood as the characteristic features of a Bosonic Josephson Junction (BJJ). For larger deviations from the stationary states, the simplifying double-well description breaks down due to the feedback of the bright component onto the dark one, causing the solitons to move. In this regime we observe intricate anharmonic and aperiodic dynamics, exhibiting remnants of the BJJ phase space.

E.T. Karamatskos et al., arXiv:1411.3957