Entangled spin pairs in graphene ENTS

石墨烯为自旋电子学提供了真正独特的机会。碳的原子序数小导致自旋-轨道相互作用的强度极弱，预计自旋弛豫时间很长。电子和核自旋之间的超精细相互作用是自旋电子学器件中自旋弛豫的另一个主要微观机制，在石墨烯中非常弱。此外，单层石墨提供了实现自旋过滤器而不需要使用铁磁材料的潜力。实现这些“全石墨烯”自旋激活器件的可能性将是革命性的，因为它将解决基于降维系统的自旋电子学中长期存在的问题，例如电导率失配问题。石墨烯也是自旋量子位（量子点）的理想主体材料，因为已知由自旋-轨道相互作用结合电子-声子耦合和与周围核的超精细相互作用引起的自旋退相干的两个主要来源是弱的。随着在超导体和石墨烯之间的混合系统中产生分离的纠缠自旋对，可以设想许多原始的可能性。这一任务的成功演示将是一个实验突破，促进了大量的量子光学类型的实验在固态下进行。我们的项目通过研究石墨烯/超导体/铁磁体混合系统中库珀对分裂和纠缠自旋对产生的几种方法来解决上述问题。石墨烯为这一目的提供了一种非常有前途的材料，但是，由于它是一种新材料，许多问题需要回答。我们的项目将以协作的方式处理这些开放问题，要么集体寻找解决方案，要么根据需要在节点之间划分任务。该项目的成果预计将是第一次在固态中展示纠缠自旋对。

Graphene offers truly unique opportunities for spintronics. The small atomic number of carbon results in an extremely weak strength of spin-orbit interaction, and very long spin relaxation times are expected. The hyperfine interaction between the electron and the nuclear spins, the other main microscopic mechanism responsible for spin relaxation in spintronics devices, is very weak in graphene. Furthermore, single-layer graphite offers the potential to realize spin-filters without the need to use ferromagnetic materials. The possibility to realize these "all-graphene" spin-active devices would be revolutionary, in that it would solve long standing issues in spintronics based on reduced dimensionality system, such as the conductivity mismatch problem. Graphene is also an ideal host material for spin qubits (quantum dots) because the two major sources of spin decoherence caused by spin-orbit interaction in combination with electron-phonon coupling and hyperfine interaction with the surrounding nuclei are known to be weak. With the generation of separated entangled pairs of spins in hybrid systems between superconductors and graphene, lots of original possibilities can be envisioned. A successful demonstration of this task would be an experimental breakthrough facilitating a multitude of quantum optics type of experiments to be performed in solid state. Our project addresses the above issues by investigating several approaches of Cooper pair splitting and generation of entangled spin pairs in graphene/superconductor/ferromagnet hybrid systems. Graphene provides an exceptionally promising material for this purpose, but, since it is a new material, many questions need to be answered. Our project will work on these open problems in a collaborative manner, either by looking for solutions collectively or by dividing tasks between the nodes as needed. The outcome of the project is expected to be the first demonstration of entangled spin pairs in the solid state.