van Driel David, Wang Guanzhong, Bordin Alberto, van Loo Nick, Zatelli Francesco, Mazur Grzegorz P, Xu Di, Gazibegovic Sasa, Badawy Ghada, Bakkers Erik P A M, Kouwenhoven Leo P, Dvir Tom
QuTech and Kavli Institute of NanoScience, Delft University of Technology, 2600, GA, Delft, The Netherlands.
Department of Applied Physics, Eindhoven University of Technology, 5600, MB, Eindhoven, The Netherlands.
Nat Commun. 2023 Oct 28;14(1):6880. doi: 10.1038/s41467-023-42026-7.
Semiconductor nanowires coupled to superconductors can host Andreev bound states with distinct spin and parity, including a spin-zero state with an even number of electrons and a spin-1/2 state with odd-parity. Considering the difference in spin of the even and odd states, spin-filtered measurements can reveal the underlying ground state. To directly measure the spin of single-electron excitations, we probe an Andreev bound state using a spin-polarized quantum dot that acts as a bipolar spin filter, in combination with a non-polarized tunnel junction in a three-terminal circuit. We observe a spin-polarized excitation spectrum of the Andreev bound state, which can be fully spin-polarized, despite strong spin-orbit interaction in the InSb nanowires. Decoupling the hybrid from the normal lead causes a current blockade, by trapping the Andreev bound state in an excited state. Spin-polarized spectroscopy of hybrid nanowire devices, as demonstrated here, is proposed as an experimental tool to support the observation of topological superconductivity.
与超导体耦合的半导体纳米线可以容纳具有不同自旋和宇称的安德列夫束缚态，包括具有偶数个电子的自旋为零的态和具有奇宇称的自旋为1/2的态。考虑到偶数态和奇数态自旋的差异，自旋过滤测量可以揭示潜在的基态。为了直接测量单电子激发的自旋，我们在三端电路中使用一个充当双极自旋过滤器的自旋极化量子点，并结合一个非极化隧道结来探测安德列夫束缚态。我们观察到安德列夫束缚态的自旋极化激发光谱，尽管在InSb纳米线中有很强的自旋轨道相互作用，但该光谱仍可以完全自旋极化。将混合体与正常引线解耦会导致电流阻塞，这是通过将安德列夫束缚态捕获在激发态实现的。如本文所示，混合纳米线器件的自旋极化光谱被提议作为一种实验工具，以支持对拓扑超导性的观测。
