Majorana bound states in a disordered quantum dot chain
Majorana bound states in a disordered quantum dot chain
复制标题
DOI：
10.1088/1367-2630/18/4/043033
复制
发表时间：
2016-01
影响因子：
3.3
通讯作者：
P. Zhang;Franco Nori;Franco Nori
中科院分区：
文献类型：
--
作者：
P. Zhang;Franco Nori;Franco Nori
研究了与s波超导体邻近耦合的半导体量子点无序链中的Majorana束缚态。通过计算其拓扑量子数，基于散射矩阵方法和紧束缚模型，我们可以确定这种非均匀一维系统的拓扑性质。我们研究了Majorana束缚态在自旋无关项（包括化学势和规则的自旋守恒跳跃）和自旋相关项（即，由于Rashba自旋-轨道耦合而引起的自旋翻转跳跃。我们发现，马约拉纳束缚态是不完全免疫的自旋无关的无序，特别是当后者是强的。同时，马约拉纳束缚态对于自旋相关无序是相对稳健的，只要自旋翻转跳跃具有统一的符号（即，变化的自旋翻转跳跃项不会沿着链改变其符号）。然而，当无序引起自旋翻转跳跃中的符号翻转时，拓扑-非拓扑相变发生在低化学势区。
We study Majorana bound states in a disordered chain of semiconductor quantum dots proximity-coupled to an s-wave superconductor. By calculating its topological quantum number, based on the scattering-matrix method and a tight-binding model, we can identify the topological property of such an inhomogeneous one-dimensional system. We study the robustness of Majorana bound states against disorder in both the spin-independent terms (including the chemical potential and the regular spin-conserving hopping) and the spin-dependent term, i.e., the spin-flip hopping due to the Rashba spin–orbit coupling. We find that the Majorana bound states are not completely immune to the spin-independent disorder, especially when the latter is strong. Meanwhile, the Majorana bound states are relatively robust against spin-dependent disorder, as long as the spin-flip hopping is of uniform sign (i.e., the varying spin-flip hopping term does not change its sign along the chain). Nevertheless, when the disorder induces sign-flip in spin-flip hopping, the topological-nontopological phase transition takes place in the low-chemical-potential region.