Anomalous Josephson current, incipient time-reversal symmetry breaking, and Majorana bound states in interacting multilevel dots
Anomalous Josephson current, incipient time-reversal symmetry breaking, and Majorana bound states in interacting multilevel dots
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DOI：
10.1103/physrevb.88.144515
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发表时间：
2013-10-25
影响因子：
3.7
通讯作者：
Egger, Reinhold
中科院分区：
文献类型：
--
作者：
Brunetti, Aldo;Zazunov, Alex;Egger, Reinhold
我们研究了自旋轨道相互作用、磁场和库仑荷电对相位差为φ的两个传统s波超导体接触的多级量子点隧道的约瑟夫森电流-相位关系I（φ）的综合影响。一个通用的模型，制定和分析的cotunneling制度（弱隧道耦合）和深subgap限制，充分考虑到相互作用的影响。我们确定了观测有限反常超电流I-a = I（phi = 0）的条件。对于具有自旋轨道耦合和任意弱塞曼场B的二能级点，我们发现在相互作用存在下，I-a的起始行为与sgn（B）成正比，表明时间反演对称性的初始自发击穿。我们还提供了实现空间分离（但拓扑不受保护）马约拉纳束缚态在这个系统的双点变体的条件。在这里，马约拉纳预测留下一个明确的签名，在2 π周期性的电流相位关系。
We study the combined effects of spin-orbit interaction, magnetic field, and Coulomb charging on the Josephson current-phase relation, I(phi), for a multilevel quantum dot tunnel contacted by two conventional s-wave superconductors with phase difference phi. A general model is formulated and analyzed in the cotunneling regime (weak tunnel coupling) and in the deep subgap limit, fully taking into account interaction effects. We determine the conditions for observing a finite anomalous supercurrent I-a = I(phi = 0). For a two-level dot with spin-orbit coupling and arbitrarily weak Zeeman field B, we find the onset behavior I-a proportional to sgn(B) in the presence of interactions, suggesting the incipient spontaneous breakdown of time-reversal symmetry. We also provide conditions for realizing spatially separated (but topologically unprotected) Majorana bound states in a double dot variant of this system. Here, Majoranas are predicted to leave a clear signature in the 2 pi-periodic current-phase relation.