Finocchiaro F, Guinea F, San-Jose P
Materials Science Factory, ICMM-CSIC, Sor Juana Ines de La Cruz 3, 28049 Madrid, Spain.
IMDEA Nanociencia, Calle de Faraday 9, 28049 Madrid, Spain.
Phys Rev Lett. 2018 Mar 16;120(11):116801. doi: 10.1103/PhysRevLett.120.116801.
We consider a two-dimensional electron gas (2DEG) in the quantum Hall regime in the presence of a Zeeman field, with the Fermi level tuned to a filling factor of ν=1. We show that, in the presence of spin-orbit coupling, contacting the 2DEG with a narrow strip of an s-wave superconductor produces a topological superconducting gap along the contact as a result of crossed Andreev reflection (CAR) processes across the strip. The sign of the topological gap, controlled by the CAR amplitude, depends periodically on the Fermi wavelength and strip width and can be externally tuned. An interface between two halves of a long strip with topological gaps of opposite sign implements a robust π junction, hosting a pair of Majorana zero modes that do not split despite their overlap. We show that such a configuration can be exploited to perform protected non-Abelian tunnel-braid operations without any fine tuning.
我们考虑处于量子霍尔 regime 且存在塞曼场的二维电子气（2DEG），费米能级调谐到填充因子 ν = 1。我们表明，在存在自旋轨道耦合的情况下，使 2DEG 与 s 波超导体的窄条接触，由于跨条的交叉安德烈夫反射（CAR）过程，会在接触处产生拓扑超导能隙。由 CAR 振幅控制的拓扑能隙的符号周期性地取决于费米波长和条带宽度，并且可以外部调节。具有相反符号拓扑能隙的长条两半之间的界面实现了一个稳健的 π 结，容纳一对即使重叠也不分裂的马约拉纳零模。我们表明，这样的配置可用于执行受保护的非阿贝尔隧道编织操作，而无需任何微调。
