Confinement in Graphene Nanostructures CONGRAN

与由半导体异质结构制成的传统量子点相比，基于石墨烯的可调谐量子点具有独特的优势，即更长的自旋相干时间，新颖的自旋效应，以及导致量子点在更高温度下运行的尺寸缩小的潜力。然而，由于克莱因隧道效应的存在，将传统的顶栅技术转移到可调谐石墨烯量子点是非常困难的。该项目旨在实施和研究目前可预见的石墨烯可调约束的三种方法，即结合顶栅极的侧向约束、偏置双层系统和磁约束。基于这些结果，基于石墨烯的量子点将被定制，可能依赖于所有三种约束方案，并针对自旋效应和高温操作的研究进行优化。在项目开始时，每个实验合作伙伴将实施一个约束方案，而理论合作伙伴则致力于开发基于石墨烯的量子点的相关模型，即能谱，无序和相互作用效应以及自旋效应。这些结果将为后续高温下自旋弛豫、引脚退相干、自旋阻滞和量子点的研究奠定基础。

Tunable graphene-based quantum dots offer unique advantages in comparison to conventional quantum dots made from semiconductor heterostructures, namely longer spin coherence times, novel spin effects, and the potential for a size reduction leading to operation of quantum dots at higher temperatures. However, transferring the conventional top gate technology to define tunable graphene-based quantum dots is nontrivial due to Klein tunneling. The project aims for the implementation and investigation of the three approaches for tunable confinement in graphene which are presently foreseen, namely combining lateral confinement with top gates, biased bilayer systems and magnetic confinement. Based on these results, graphene-based quantum dots will be tailored which potentially rely on all three confinement schemes and are optimized for the investigation of spin effects and operation at elevated temperatures. At the beginning of the project, each experimental partner will implement one confinement scheme, while the theory partners work on development of relevant models for the graphene based quantum dots, namely energy spectra, effects of disorder and interactions, and spin effects. These results will form the basis for the subsequent investigations of spin relaxation and pin decoherence, spin blockade and gdots at elevated temperatures.