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arXiv 1102.2028cond-mat.str-el
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一维玻色-哈伯德模型的动力学性质

Dynamic properties of the one-dimensional Bose-Hubbard model

S. Ejima, H. Fehske, F. Gebhard

摘要:

利用密度矩阵重整化群方法研究了超冷玻色原子在光晶格中的有效模型--一维玻色-哈伯德模型的基态和动力学性质.对于固定的最大网站占用$n_b=5$,我们计算之间的相位边界的莫特绝缘体和“超流”相最低的两个莫特瓣。我们从密度-密度关联函数中提取了Tomonaga-Luttinger参数,精确地确定了Mott跃迁的临界相互作用强度。对于这两个相,我们研究了均匀系统中的动量分布函数以及抛物形陷阱中的粒子分布和准动量分布函数。用我们的零温方法,我们测定了莫特绝缘体和一维玻色-哈伯德模型的“超流”相的光电子谱。在绝缘体中,Mott间隙将准粒子色散和准空穴色散分开。在“超流体”阶段,光谱权重集中在零动量附近。

英文摘要:

We use the density-matrix renormalization group method to investigate ground-state and dynamic properties of the one-dimensional Bose-Hubbard model, the effective model of ultracold bosonic atoms in an optical lattice. For fixed maximum site occupancy $n_b=5$, we calculate the phase boundaries between the Mott insulator and the `superfluid' phase for the lowest two Mott lobes. We extract the Tomonaga-Luttinger parameter from the density-density correlation function and determine accurately the critical interaction strength for the Mott transition. For both phases, we study the momentum distribution function in the homogeneous system, and the particle distribution and quasi-momentum distribution functions in a parabolic trap. With our zero-temperature method we determine the photoemission spectra in the Mott insulator and in the `superfluid' phase of the one-dimensional Bose-Hubbard model. In the insulator, the Mott gap separates the quasi-particle and quasi-hole dispersions. In the `superfluid' phase the spectral weight is concentrated around zero momentum.

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