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arXiv 0907.2928cond-mat.quant-gascond-mat.other
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玻色-哈伯德模型的动力学平均场论

Dynamical Mean Field Theory for the Bose-Hubbard Model

Wen-Jun Hu, Ning-Hua Tong

摘要:

动力学平均场论(DMFT)在强关联费米子的研究中是成功的,最近被扩展到玻色子系统[Phys. Rev. B { \textbf 77},235106(2008)]。本文利用玻色DMFT方法研究了描述格点中玻色子在格点相互作用的玻色-哈伯德模型。采用精确对角化方法求解杂质,得到了Bethe格点上格林函数、占据密度和凝聚分数的DMFT解。不同的阶段被确定:莫特绝缘体,玻色-爱因斯坦凝聚(BEC)相,和正常的阶段。在有限的温度下,我们得到了Mott状制度和正常相之间的交叉,以及BEC正常相变。产生在$μ/U-\tilde{t}/U$平面和在$T/U-\tilde{t}/U$平面上的相图($\tilde{t}$是缩放的跳变幅度)。我们比较了我们的结果与以前的,并讨论了这些结果的实验意义。

英文摘要:

The dynamical mean field theory (DMFT), which is successful in the study of strongly correlated fermions, was recently extended to boson systems [Phys. Rev. B {\textbf 77}, 235106 (2008)]. In this paper, we employ the bosonic DMFT to study the Bose-Hubbard model which describes on-site interacting bosons in a lattice. Using exact diagonalization as the impurity solver, we get the DMFT solutions for the Green's function, the occupation density, as well as the condensate fraction on a Bethe lattice. Various phases are identified: the Mott insulator, the Bose-Einstein condensed (BEC) phase, and the normal phase. At finite temperatures, we obtain the crossover between the Mott-like regime and the normal phase, as well as the BEC-to-normal phase transition. Phase diagrams on the $μ/U-\tilde{t}/U$ plane and on the $T/U-\tilde{t}/U$ plane are produced ($\tilde{t}$ is the scaled hopping amplitude). We compare our results with the previous ones, and discuss the implication of these results to experiments.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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