利用无扭转双电子学研究人工双层膜中的量子反常霍尔相
Quantum anomalous Hall phase in synthetic bilayers via twistless twistronics
摘要：
我们最近提出了基于超冷原子和合成维度的“类双光子”物理学的量子模拟器[Phys. Rev. Lett. 125，030504（2020）]。从概念上讲，该方案是基于这样的想法，即通过识别具有合成空间维度的被困原子的内部状态，将具有所需几何形状的物理单层光晶格升级为合成双层系统。通过激光诱导拉曼跃迁可以精确地控制两层晶格内态之间的耦合，通过空间调制层间耦合，可以在晶格上直接压印出莫尔条纹，而不需要对层进行物理扭曲。这种方案实际上导致了整个晶格的均匀图案，并具有可广泛调节的层间耦合强度的额外优势。后一个特点有利于工程的平带在更大的“魔”角，或更直接，为较小的单位细胞比在conventionaltwisted材料。在本文中，我们扩展了这些想法，并证明了我们的系统在适当的条件下表现出topologicalband结构。为了实现非平凡的能带拓扑结构，我们考虑imanaginarynext-to-nearest neighbor隧穿，驱动系统进入量子反常霍尔相位。特别地，我们关注三组能带，它们的Chern数三元组可以与平凡绝缘体（0，0，0）、标准非平凡绝缘体（-1，0，1）和非标准非平凡绝缘体（-1，1，0）相关联。我们确定了这三种情况发生的参数制度。我们发现了反常霍尔相的存在和拓扑边缘态的出现。我们的工作为在不使用ATWIST的情况下进行双电子学拓扑效应的实验开辟了道路
英文摘要：
We recently proposed quantum simulators of "twistronic-like" physics based on ultracold atoms and syntheticdimensions [Phys. Rev. Lett. 125, 030504 (2020)]. Conceptually, the scheme is based on the idea that aphysical monolayer optical lattice of desired geometry is upgraded to a synthetic bilayer system by identifyingthe internal states of the trapped atoms with synthetic spatial dimensions. The couplings between the internalstates, i.e. between sites on the two layers, can be exquisitely controlled by laser induced Raman transitions.By spatially modulating the interlayer coupling, Moiré-like patterns can be directly imprinted on the latticewithout the need of a physical twist of the layers. This scheme leads practically to a uniform pattern across thelattice with the added advantage of widely tunable interlayer coupling strengths. The latter feature facilitates theengineering of flat bands at larger "magic" angles, or more directly, for smaller unit cells than in conventionaltwisted materials. In this paper we extend these ideas and demonstrate that our system exhibits topologicalband structures under appropriate conditions. To achieve non-trivial band topology we consider imanaginarynext-to-nearest neighbor tunnelings that drive the system into a quantum anomalous Hall phase. In particular,we focus on three groups of bands, whose their Chern numbers triplet can be associated to a trivial insulator(0,0,0), a standard non-trivial (-1,0,1) and a non-standard non-trivial (-1,1,0). We identify regimes of parameterswhere these three situations occur. We show the presence of an anomalous Hall phase and the appearance oftopological edge states. Our works open the path for experiments on topological effects in twistronics without atwist
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