Spin states in carbon nanotube and graphene double quantum dots with charge detection

基于石墨烯和碳纳米管（CNTs）的碳纳米结构本质上是低维系统，具有很好的量子电子学特性。由于两种材料体系的自旋轨道耦合较低，核自旋丰度较小，因此自旋散射预计较小。因此，需要较长的自旋弛豫时间和相干时间，这是相干自旋信息处理的必要条件。在这个项目中，我们想要探索碳纳米结构的基本性质和这些系统中的电子自旋弛豫。这是固态自旋量子比特和量子电子器件发展的重要一步。自旋态将在碳纳米管（A部分，FZJ）和石墨烯（B部分，RWTH）中制备的量子点中进行研究。这些状态将通过在不同磁场下的低噪量子输运测量来表征。这两种材料系统必须解决不同的挑战。在碳纳米管子项目中，重点将放在实现自旋松弛时间和拉比振荡定量评估的高频技术上。在石墨烯子项目中，我们重点研究了集成电荷检测的石墨烯双量子点的制备和表征。在两个部分实现的元件将允许测量两种材料系统中的自旋相干时间。

Carbon nanostructures based on graphene and carbon nanotubes (CNTs) are intrinsically low-dimensional systems with promising properties for quantum electronics. Spin scattering in both material systems is expected to be small because of their low spin-orbit coupling and the small abundance of nuclear spins. Therefore, long spin relaxation and coherence times are expected, which are essential for coherent spin-based information processing. In this project, we want to explore the fundamental properties of carbon nanostructures and the electron spin relaxation within these systems. This is an important step for the development of solid-state spin qubits and quantum electronic devices in general. The spin states will be studied in quantum dots fabricated in carbon nanotubes (part A, FZJ) and in graphene in the few-electron / few-hole regime (part B, RWTH). The states will be characterized by low-loise quantum transport measurements at varying magnetic field. Different challenges have to be addressed for both material systems. In the CNT sub-project, the focus will be on implementing high-frequency techniques for the quantitative assessment of spin relaxation times and Rabi oscillations. In the graphene sub-project we focus on the fabrication and characterization of graphene double quantum dots with integrated charge detection. The elements realized in the two parts will allow measurements of spin coherence times in both material systems.