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arXiv · 0805.4447

Sign of tunnel coupling in barrier-separated Bose-Einstein condensates and stability of double-ring systems

Joachim Brand·Tania J. Haigh·Ulrich Zülicke
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Abstract

We revisit recent claims about the instability of non-rotating tunnel coupled annular Bose-Einstein condensates leading to the emergence of angular-momentum Josephson oscillation [Phys. Rev. Lett. 98, 050401 (2007), arXiv:quant-ph/0609133v2]. It was predicted that all stationary states with uniform density become unstable in certain parameter regimes. By careful analysis, we arrive at a different conclusion. We show that there is a stable non-rotating and uniform ground state for any value of the tunnel coupling and repulsive interactions. The instability of an excited state with $π$ phase difference between the condensates can be interpreted in terms of the familiar snake instability. We further discuss the sign of the tunnel coupling through a separating barrier, which carries significance for the nature of the stationary states. It is found to always be negative for physical reasons.

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Joachim Brand, Tania J. Haigh, Ulrich Zülicke. 2009-08-16. Sign of tunnel coupling in barrier-separated Bose-Einstein condensates and stability of double-ring systems. https://doi.org/10.1103/physreva.81.025602

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