Spin coherence, spin qubits, and spin transport in carbon nanostructures

该理论项目涉及碳基纳米结构中的自旋相干性和磁相互作用，如量子点（QDs）、纳米片、纳米带（gnr）和碳纳米管（CNTs）以及扩展石墨烯。我们主要研究：(1)局域电子在量子点和纳米片中的自旋性质，它们与移动自旋性质有很大的不同。基于准一维材料（gnr, CNTs）的量子点中的自旋物理有望不同于二维结构。(2)石墨烯中移动电子的自旋相干性和弛豫性已经得到了实验研究，但目前还不清楚它们的各向异性等几个方面。进一步的动机来自于相干性至关重要的量子比特的潜在用途。碳是一种非传统但很有前途的自旋量子比特和其他自旋电子学应用材料。与III-V型半导体相比，碳中的自旋轨道耦合较弱，允许较长的自旋弛豫时间T1。碳也有非常稀的核自旋，允许长自旋相干乘以T2。我们建议继续现有的项目（第一个资助期的结果，见下文）。项目主题没有变化，但有以下重要调整：(1)项目扩展，现由两名主要研究人员领导（亚琛工业大学的C. Honerkamp申请加入研究小组）。(2)项目更侧重于材料，我们现在专注于碳，这是我们在第一个资助期取得了最好的成果，这与其他项目的重组是一致的。

This theory project deals with spin coherence and magnetic interactions in carbon- based nanostructures such as quantum dots (QDs), nanoflakes, nanoribbons (GNRs), and carbon nanotubes (CNTs), as well as extended graphene. We focus on: (1) Spin properties of localized electrons in QDs and nanoflakes which can deviate substantially from that of mobile spins. Spin physics in QDs based on quasi-1D materials (GNRs, CNTs) are expected to be different from 2D structures. (2) Spin coherence and relaxation of mobile electrons in graphene have been studied experimentally [1], but several aspects such as their anisotropy are not understood at this point. Further motivation comes from the potential use as qubits where coherence is essential. Carbon is an unconventional but promising material for spin qubits and other spintronics applications. In contrast to III-V semiconductors, spin-orbit coupling in carbon is weak, allowing for long spin relaxartion times T1. Carbon also has very dilute nuclear spins, allowing for long spin coherence times T2. We propose to continue an existing project (results from the first funding period, see below). The topic of the project is unchanged, with these important adjustments: (1) The project is extended and now lead by two principal investigators (C. Honerkamp of RWTH Aachen applies to join the Research Unit). (2) The project is more focused in terms of materials, as we now concentrate on carbon where we have achieved the best results in the first funding period and which is in line with the regrouping of the other projects.