Twisted bilayer graphene (t-BLG) has recently been introduced as a rich physical platform displaying flat electronic bands, strongly correlated states, and unconventional superconductivity. Studies have hinted at an unusual Z₂ topology of the moiré Dirac bands of t-BLG. However, direct experimental evidence of this moiré band topology and associated edge states is still lacking. Herein, using superconducting quantum interferometry, we reconstructed the spatial supercurrent distribution in t-BLG Josephson junctions and revealed the presence of edge states located in the superlattice band gaps. The absence of edge conduction in high resistance regions just outside the superlattice band gap confirms that the edge transport originates from the filling of electronic states located inside the band gap and further allows us to exclude several other edge conduction mechanisms. These results confirm the unusual moiré band topology of twisted bilayer graphene and will stimulate further research to explore its consequences.

中文翻译：

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揭示扭曲双层石墨烯中的拓扑边缘状态

最近引入了扭曲双层石墨烯 (t-BLG) 作为一个丰富的物理平台，显示出平坦的电子能带、强相关态和非常规的超导性。研究暗示了一个不寻常的Z ₂t-BLG 的莫尔狄拉克带的拓扑结构。然而，仍然缺乏这种莫尔带拓扑结构和相关边缘状态的直接实验证据。在此，使用超导量子干涉仪，我们重建了 t-BLG Josephson 结中的空间超电流分布，并揭示了位于超晶格带隙中的边缘态的存在。在超晶格带隙之外的高电阻区域中没有边缘传导证实了边缘传输源于位于带隙内的电子态的填充，并进一步允许我们排除其他几种边缘传导机制。这些结果证实了扭曲双层石墨烯不寻常的莫尔带拓扑结构，并将激发进一步的研究以探索其后果。