论文标题
具有平面带的跨玻色子中对称性保护的拓扑阶段
Symmetry-protected Topological Phases in Spinful Bosons with a Flat Band
论文作者
论文摘要
从理论上讲，我们可以证明，相互作用的对称性保护拓扑（SPT）阶段可以通过装载在晶格上的超声稀疏的骨气原子来实现，这些骨质原子在晶体结构的底部有一个平坦的带。这种系统的基础状态不是常规的莫特绝缘子，因为地面状态不仅具有自旋波动，而且还具有不可忽略的电荷波动。此类系统中的SPT阶段由零温度下的自旋和电荷波动确定。我们发现，在某些特殊情况下，可以准确获得此类系统的多体接地状态，并且这些确切的基态被证明是SPT阶段的代表性状态。作为一个具体的例子，我们证明了锯齿链上的旋转1玻色子可以在$ \ mathbb {z} _2 \ times \ times \ mathbb {z} _2 $旋转旋转对称对称性或时间反向对称性的SPT相位，而SPT相位是SPT相位的结果。我们还表明，Kagome晶格上的Spin-3玻色子可以在受$ D_2 $点组对称性保护的SPT相位，但是该SPT相是电荷波动的结果。
We theoretically demonstrate that interacting symmetry-protected topological (SPT) phases can be realized with ultracold spinful bosonic atoms loaded on the lattices which have a flat band at the bottom of the band structure. Ground states of such systems are not conventional Mott insulators in the sense that the ground states possess not only spin fluctuations but also non-negligible charge fluctuations. The SPT phases in such systems are determined by both spin and charge fluctuations at zero temperature. We find that the many-body ground states of such systems can be exactly obtained in some special cases, and these exact ground states turn out to serve as representative states of the SPT phases. As a concrete example, we demonstrate that spin-1 bosons on a sawtooth chain can be in an SPT phase protected by $\mathbb{Z}_2 \times \mathbb{Z}_2$ spin rotation symmetry or time-reversal symmetry, and this SPT phase is a result of spin fluctuations. We also show that spin-3 bosons on a kagome lattice can be in an SPT phase protected by $D_2$ point group symmetry, but this SPT phase is, however, a result of charge fluctuations.
