Hell Michael, Leijnse Martin, Flensberg Karsten
Center for Quantum Devices and Station Q Copenhagen, Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark.
Division of Solid State Physics and NanoLund, Lund University, Box 118, S-22100 Lund, Sweden.
Phys Rev Lett. 2017 Mar 10;118(10):107701. doi: 10.1103/PhysRevLett.118.107701.
We model theoretically a two-dimensional electron gas (2DEG) covered by a superconductor and demonstrate that topological superconducting channels are formed when stripes of the superconducting layer are removed. As a consequence, Majorana bound states (MBSs) are created at the ends of the stripes. We calculate the topological invariant and energy gap of a single stripe, using realistic values for an InAs 2DEG proximitized by an epitaxial Al layer. We show that the topological gap is enhanced when the structure is made asymmetric. This can be achieved either by imposing a phase difference (by driving a supercurrent or using a magnetic-flux loop) over the strip or by replacing one superconductor by a metallic gate. Both strategies also enable control over the MBS splitting, thereby facilitating braiding and readout schemes based on controlled fusion of MBSs. Finally, we outline how a network of Majorana stripes can be designed.
我们从理论上对覆盖有超导体的二维电子气（2DEG）进行建模，并证明当超导层的条带被去除时会形成拓扑超导通道。结果，在条带的末端会产生马约拉纳束缚态（MBSs）。我们使用由外延Al层近邻化的InAs 2DEG的实际值，计算了单个条带的拓扑不变量和能隙。我们表明，当结构变得不对称时，拓扑能隙会增强。这可以通过在条带上施加相位差（通过驱动超电流或使用磁通量回路）或用金属栅极替换一个超导体来实现。这两种策略还能够控制MBS分裂，从而促进基于MBSs可控融合的编织和读出方案。最后，我们概述了如何设计马约拉纳条带网络。
