Thermal and quantum fluctuations of confined Bose-Einstein condensate beyond the Bogoliubov approximation

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• 作者：Y. Nakamura^a ; ^b ; ^{yusuke.n@asagi.waseda.jp} ; T. Kawaguchi^a ; ^{pionelish30@toki.waseda.jp} ; Y. Torii^a ; ^{torii0139@asagi.waseda.jp} ; Y. Yamanaka^a ; ^{yamanaka@waseda.jp}
• 关键词：Bose&ndash ; Einstein condensation ; Quantum field theory ; Zero mode ; Cold atom ; Spontaneous symmetry breaking ; Finite temperature
• 刊名：Annals of Physics
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：376
• 期：Complete
• 页码：484-498
• 全文大小：593 K
• 卷排序：376

文摘

The formulation for zero mode of a Bose–Einstein condensate beyond the Bogoliubov approximation at zero temperature [Y. Nakamura et al., Phys. Rev. A 89 (2014) 013613] is extended to finite temperature. Both thermal and quantum fluctuations are considered in a manner consistent with a concept of spontaneous symmetry breakdown for a finite-size system. Therefore, we need a proper treatment of the zero mode operators, which invoke non-trivial enhancements in depletion condensate and thermodynamical quantities such as the specific heat. The enhancements are visible in the weak interaction case. Our approach reproduces the results of a homogeneous system in the Bogoliubov approximation in a large particle number limit.