Phase diagram and pair Tomonaga-Luttinger liquid in a Bose-Hubbard model with flat bands
Phase diagram and pair Tomonaga-Luttinger liquid in a Bose-Hubbard model with flat bands
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DOI：
10.1103/physreva.88.063613
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发表时间：
2013-09
影响因子：
2.9
通讯作者：
S. Takayoshi;H. Katsura;N. Watanabe;H. Aoki
中科院分区：
文献类型：
--
作者：
S. Takayoshi;H. Katsura;N. Watanabe;H. Aoki
为了探索平带系统中的超流性，我们考虑了具有 $\pi$ 通量的交联梯上的 Bose-Hubbard 模型，该模型具有一个平带，与非相互作用粒子的其他带之间有间隙，我们在其中非微扰地研究了现场排斥的影响。对于低密度，我们找到了精确的简并基态，每个基态都是维格纳固体，在平带上具有不重叠的万尼尔态。在较高密度下，多体系统当投影到较低的平带上时，可以映射到自旋链模型。这种映射使我们能够揭示由玻色子对组成的 Tomonaga-Luttinger 液体的存在。有趣的是，高密度区域和低密度区域有重叠，两相共存。
To explore superfluidity in flat-band systems, we consider a Bose-Hubbard model on a cross-linked ladder with $\pi$ flux, which has a flat band with a gap between the other band for noninteracting particles, where we study the effect of the on-site repulsion nonperturbatively. For low densities, we find exact degenerate ground states, each of which is a Wigner solid with nonoverlapping Wannier states on the flat band. At higher densities, the many-body system, when projected onto the lower flat band, can be mapped to a spin-chain model. This mapping enables us to reveal the existence of a Tomonaga-Luttinger liquid comprising it pairs of bosons. Interestingly, the high- and low- density regions have an overlap, where the two phases coexist.