The condition for the appearance of dynamical instability of the Bose-condensed system, characterized by the emergence of complex eigenvalues in the Bogoliubov-de Gennes equations, is studied analytically. It is concluded that the degeneracy between a positive-norm eigenmode and a negative-norm one is essential for the emergence of complex modes. Based on the conclusion, we justify the two-mode approximation applied in our previous work, in which we analytically studied the condition for the existence of complex modes when the condensate has a highly quantized vortex.
|ジャーナル||Physical Review A - Atomic, Molecular, and Optical Physics|
|出版ステータス||Published - 2008 4月 1|
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