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

基于石墨烯和碳纳米管的碳纳米结构是本质上低维的体系，具有很好的量子电子学性能。这两个材料系统中的自旋散射预计会很小，因为它们的自旋-轨道耦合很低，而且核自旋的丰度很小。因此，需要较长的自旋弛豫时间和相干时间，这对于基于自旋的相干信息处理是必不可少的。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。这是发展固态自旋量子比特和量子电子器件的重要一步。我们将研究在碳纳米管(A部分，FZJ)和石墨烯(B部分，RWTH)中制备的量子点的自旋态。这些态将通过在不同磁场下的低噪声量子输运测量来表征。对于这两种材料系统，必须解决不同的挑战。在碳纳米管子项目中，重点将是实施用于定量评估自旋弛豫时间和拉比振荡的高频技术。在石墨烯项目中，我们重点研究了具有集成电荷探测功能的石墨烯双量子点的制备和表征。在这两个部分中实现的元素将允许测量两个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.