Superfluidity of Bose—Einstein condensates in ultracold atomic gases
Zhu Qi-Zhonga) , Wu Biaoa), b), c)† 
Superfluidity of Bose—Einstein condensates in ultracold atomic gases |
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Zhu Qi-Zhong
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| Stability phase diagrams of BEC Bloch states in optical lattices. k is the wave number of BEC Bloch waves; q denotes the wave number of perturbation modes. In the shaded (light or dark) area, the perturbation mode has negative excitation energy; in the dark shaded area, the mode grows or decays exponentially in time. The triangles in (a1–a4) represent the boundary, q 2/4 + c = k 2, of saddle point regions at v = 0. The solid dots in the first column are from the analytical results of Eq. ( 20 ). The circles in (b1) and (c1) are based on the analytical expression ( 21 ). The dashed lines indicate the most unstable modes for each Bloch wave ψ k .[ 29 ] |
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