Magnetically confined graphene quantum dots

这个项目是基于我们最近利用朗道能级隙结合局部电场实现的光滑受限石墨烯量子点。与光刻石墨烯量子点相比，这些点在轨道、谷和自旋水平的填充序列方面似乎更受控制，而光刻石墨烯量子点通常会受到边缘无序的影响。特别是，我们发现了强大的轨道分裂和谷分裂，这与详细的紧密结合计算非常吻合。通过亚纳米位移来改变量子点相对于石墨烯在六方氮化硼上的上层结构的横向位置，还可以在10 meV范围内精确调节不同的能量尺度。到目前为止，这些显著的结果仅限于扫描隧道显微镜的尖端，该显微镜同时用于充电和探测量子点。该项目旨在-开发多个接触实验，包括后门和额外的侧接触，以提供对这种新型量子点的调谐和精确控制，-对量子点电子进行动态测量，达到亚ns时间尺度，目标是利用理论上预测的石墨烯量子点的有利弛豫和相干性。-建立一个全面的理论模型，以了解不同时间和长度尺度下的点动态。

This project is based on our recent realization of smoothly confined graphene quantum dots using Landau level gaps in combination with local electric fields. These dots appear to be much more controlled in terms of filling sequences by orbital, valley and spin levels than lithographic graphene quantum dots, which typically suffer from edge disorder. In particular, robust orbital and valley splittings are identified, in excellent agreement with detailed tight-binding calculations. Changing the lateral position of the quantum dot by sub-nm displacements with respect to the superstructure of graphene on hexagonal boron nitride additionally allows for accurate tuning of the different energy scales with variations in the 10 meV range. These remarkable results are so far restricted to the tip of a scanning tunneling microscope, which is used simultaneously to charge and to probe the quantum dot. This project aims to- develop multiple contact experiments including back gates and additional side contacts in order to provide tuning and precise control of this novel type of quantum dot,- perform dynamic measurements of the quantum dot electrons down to the sub-ns time scale targeting the exploitation of the theoretically predicted favorable relaxation and coherence properties of graphene quantum dots.- develop a comprehensive theoretical model to understand the dot dynamics at different time and length scales.