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Excitation spectrum and instability of a two-species Bose-Einstein condensate

D. Gordon·C. M. Savage
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Abstract

We numerically calculate the density profile and excitation spectrum of a two-species Bose-Einstein condensate for the parameters of recent experiments. We find that the ground state density profile of this system becomes unstable in certain parameter regimes, which leads to a phase transition to a new stable state. This state displays spontaneously broken cylindrical symmetry. This behavior is reflected in the excitation spectrum: as we approach the phase transition point, the lowest excitation frequency goes to zero, indicating the onset of instability in the density profile. Following the phase transition, this frequency rises again.

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D. Gordon, C. M. Savage. 1998-02-24. Excitation spectrum and instability of a two-species Bose-Einstein condensate. https://doi.org/10.1103/physreva.58.1440

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