棋盘格超晶格上硬核Bose-哈伯德模型的Phase diagram
Phase diagram of the hardcore Bose-Hubbard model on a checkerboard superlattice
摘要：
在二维和三维中，我们得到了存在周期为2的超晶格的硬核Bose-哈伯德模型的完整相图。首先，我们获得的超流相和“平凡的”绝缘相的模型（完全空的和完全填充的晶格）分析之间的相边界。接下来，超流相和半填充莫特绝缘相之间的边界数值获得，使用随机级数展开（SSE）算法，然后通过有限尺寸标度。我们还比较了我们的数值计算结果对几个近似方案的预测，包括两个平均场的方法和四阶强耦合展开（SCE），我们表明，后者的方法，特别是成功地产生一个准确的图片的相图。最后，我们研究在何种程度上的几个近似方案，如随机相位近似和强耦合展开，给出了一个准确的描述内的绝缘相的玻色子的动量分布。
英文摘要：
We obtain the complete phase diagram of the hardcore Bose-Hubbard model in the presence of a period-two superlattice in two and three dimensions. First we acquire the phase boundaries between the superfluid phase and the `trivial' insulating phases of the model (the completely-empty and completely-filled lattices) analytically. Next, the boundary between the superfluid phase and the half-filled Mott-insulating phase is obtained numerically, using the stochastic series expansion (SSE) algorithm followed by finite-size scaling. We also compare our numerical results against the predictions of several approximation schemes, including two mean-field approaches and a fourth-order strong-coupling expansion (SCE), where we show that the latter method in particular is successful in producing an accurate picture of the phase diagram. Finally, we examine the extent to which several approximation schemes, such as the random phase approximation and the strong-coupling expansion, give an accurate description of the momentum distribution of the bosons inside the insulating phases.
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