Phys. Rev. A 81, 025602 (2010) [4 pages]Sign of coupling in barrier-separated Bose-Einstein condensates and stability of double-ring systemsReceived 28 May 2008; published 8 February 2010 We revisit recent claims about the instability of nonrotating tunnel coupled annular Bose-Einstein condensates leading to the emergence of angular momentum Josephson oscillation [ Phys. Rev. Lett. 98 050401 (2007)]. 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 nonrotating 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. © 2010 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevA.81.025602
DOI:
10.1103/PhysRevA.81.025602
PACS:
03.75.Lm, 03.75.Kk, 03.75.Mn
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