论文标题
旋转对称性断裂和非平凡拓扑的双层石墨烯量子点的可视化和操纵
Visualization and Manipulation of Bilayer Graphene Quantum Dots with Broken Rotational Symmetry and Nontrivial Topology
论文作者
论文摘要
Bernal堆叠的双层石墨烯（BLG）中静电定义的量子点（QD）是一个有前途的量子信息平台，因为它们的旋转式变色时间很长，样品质量高和可调性。重要的是，QD状态的形状决定了电子能谱，电子之间的相互作用以及电子与环境的耦合，所有这些都与量子信息处理有关。尽管它很重要，但BLG QD状态的形状仍未在实验上进行检查。在这里，我们通过使用扫描隧道显微镜报告BLG QD状态的直接可视化。令人惊讶的是，我们发现这些状态表现出强大的旋转对称性。通过使用数值紧密结合模型，我们确定观察到的断裂旋转对称性可以归因于低能量各向异性带。然后，我们比较了狭窄的孔和电子，并演示了BLG的非平凡带拓扑的影响。我们的研究将BLG QD与具有微不足道的带拓扑的QD平台区分开。
Electrostatically defined quantum dots (QDs) in Bernal stacked bilayer graphene (BLG) are a promising quantum information platform because of their long spin decoherence times, high sample quality, and tunability. Importantly, the shape of QD states determines the electron energy spectrum, the interactions between electrons, and the coupling of electrons to their environment, all of which are relevant for quantum information processing. Despite its importance, the shape of BLG QD states remains experimentally unexamined. Here we report direct visualization of BLG QD states by using a scanning tunneling microscope. Strikingly, we find these states exhibit a robust broken rotational symmetry. By using a numerical tight-binding model, we determine that the observed broken rotational symmetry can be attributed to low energy anisotropic bands. We then compare confined holes and electrons and demonstrate the influence of BLG's nontrivial band topology. Our study distinguishes BLG QDs from prior QD platforms with trivial band topology.
