论文标题
在淋巴结非中心超级导体的结构化表面上的majoraana扁平带
Majorana flat bands at structured surfaces of nodal noncentrosymmetric superconductors
论文作者
论文摘要
节点非中心对称超导体的表面可以容纳Majorana模式的平坦带，如果可以找到操纵局部Majorana波数据包的方法，则可以为量子计算提供有前途的平台。当将一部分表面遭受铁磁绝缘子引起的交换场时，我们研究了这种平坦带的命运。我们使用精确的对角度来找到模型系统中Bogoliubov-De Gennes Hamiltonian的特征态和特征力，为此，沿着平板表面的条带沿一条带状板施加了交换场。我们考虑条带和应用场的不同方向。如果沿田间方向的无场系统的自旋极化足够大的扰动理论可以预测，大多数位于交换场带的状态的能量会从零能量上移动，而不是与田间强度成比例的量。另一方面，对应于位于无磁场上的状态的状态仅受现场影响。确切的对角度证实了这一点。此外，我们讨论了一个将小型交换字段应用于以前的无场面带，目的是引入线性分散。通过打开和关闭此分散，可以沿特定方向移动波数据包。我们发现，在我们的模型系统中，确实可以实现线性分散。可以通过无场表面的动量依赖性自旋极化来预测这种分散体的定性特征。
Surfaces of nodal noncentrosymmetric superconductors can host flat bands of Majorana modes, which provide a promising platform for quantum computation if one can find methods for manipulating localized Majorana wave packets. We study the fate of such flat bands when part of the surface is subjected to an exchange field induced by a ferromagnetic insulator. We use exact diagonalization to find the eigenstates and eigenenergies of the Bogoliubov-de Gennes Hamiltonian of a model system, for which an exchange field is applied along a strip on the surface of a slab. We consider different orientations of the strip and the applied field. If the spin polarization of the field-free system along the field direction is sufficiently large perturbation theory predicts that energies of states which are mostly localized on the exchange-field strip are shifted away from zero energy by an amount proportional to the field strength. On the other hand, energies corresponding to states localized on the field-free strip are only weakly affected by the field. Exact diagonalization confirms this. Moreover, we discuss a setup with a small exchange field applied to the previously field-free strip with the goal of introducing a linear dispersion. By switching this dispersion on and off, a wave packet could be moved in a certain direction. We find that in our model system, a linear dispersion can indeed be achieved. The qualitative features of this dispersion can be predicted from the momentum-dependent spin polarization of the field-free surface.
