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有吸引力的玻色-爱因斯坦凝聚体中孤子形成的临界涨落

Critical fluctuations in a soliton formation of attractive Bose-Einstein condensates

Rina Kanamoto, Hiroki Saito, Masahito Ueda

摘要:

我们采用平均场、Bogoliubov和多体理论来研究玻色-爱因斯坦凝聚体的位置和动量的临界涨落,该凝聚体的平移对称性由于吸引相互作用而自发破缺。在均匀系统中,保对称哈密顿量的多体基态对低能级的叠加是非常脆弱的,而平均场论预言了自发破坏平移对称性的稳定亮孤子.我们证明了弱的破缺微扰使对称多体基态跃迁到多体亮孤子。我们认为,孤子态的质心涨落主要是由凝聚态向平移模的耗尽引起的。我们发展了一个扩展的平均场论来解析地再现精确对角化方法得到的这些结果。

英文摘要:

We employ mean-field, Bogoliubov, and many-body theories to study critical fluctuations in position and momentum of a Bose-Einstein condensate whose translation symmetry is spontaneously broken due to attractive interactions. In a homogeneous system, the many-body ground state of the symmetry-preserving Hamiltonian is very fragile against superposition of low-lying states, while mean-field theory predicts a stable bright soliton which spontaneously breaks translation symmetry. We show that weak symmetry-breaking perturbations cause the translation-symmetric many-body ground state to cross over to a many-body bright soliton. We argue that the center-of-mass fluctuations in the soliton state arise primarily from the depletion of the condensate to translation modes. We develop an extended mean-field theory to analytically reproduce these results obtained by the exact diagonalization method.

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