Tan Z B, Cox D, Nieminen T, Lähteenmäki P, Golubev D, Lesovik G B, Hakonen P J
Low Temperature Laboratory, Department of Applied Physics, Aalto University, P.O. Box 15100, FI-00076 Aalto, Finland.
L.D. Landau Institute for Theoretical Physics RAS, Chernogolovka, 142432 Moscow Region, Russia.
Phys Rev Lett. 2015 Mar 6;114(9):096602. doi: 10.1103/PhysRevLett.114.096602. Epub 2015 Mar 4.
A split Cooper pair is a natural source for entangled electrons which is a basic ingredient for quantum information in the solid state. We report an experiment on a superconductor-graphene double quantum dot (QD) system, in which we observe Cooper pair splitting (CPS) up to a CPS efficiency of ∼10%. With bias on both QDs, we are able to detect a positive conductance correlation across the two distinctly decoupled QDs. Furthermore, with bias only on one QD, CPS and elastic cotunneling can be distinguished by tuning the energy levels of the QDs to be asymmetric or symmetric with respect to the Fermi level in the superconductor.
分裂的库珀对是纠缠电子的天然来源，而纠缠电子是固态量子信息的基本要素。我们报告了一项关于超导体 - 石墨烯双量子点（QD）系统的实验，在该实验中我们观察到库珀对分裂（CPS），其效率高达约10%。当两个量子点都施加偏压时，我们能够检测到两个明显解耦的量子点之间的正电导相关性。此外，仅对一个量子点施加偏压时，通过将量子点的能级相对于超导体中的费米能级调制成不对称或对称，可以区分库珀对分裂和弹性共隧穿。
