Josephson effect in multiterminal topological junctions
Josephson effect in multiterminal topological junctions
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DOI：
10.1103/physrevb.96.024516
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发表时间：
2017-06
影响因子：
3.7
通讯作者：
A. Zazunov;R. Egger;M. Alvarado;A. Yeyati
中科院分区：
文献类型：
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作者：
A. Zazunov;R. Egger;M. Alvarado;A. Yeyati
我们研究了由两根拓扑超导体(TS线)和一个常规的S波超导体组成的三结中的约瑟夫森效应。利用边界格林函数理论，利用Kitaev链的低能极限对TS导线进行建模，得到了各种极限情况下电流-相位关系的解析结果。我们发现约瑟夫森输运严重依赖于TS线的边界自旋极化之间的自旋倾斜角，这反过来表明可以通过超流测量来获得Majorana态的自旋结构。我们还将边界格林函数方法扩展到一个更微观的自旋线模型，从而计算了$\theta$与实验上可获得的参数，如塞曼场和/或化学势的关系。此外，我们还证明了由于常规超导导线有效地锁定了三结的费米子宇称，两根TS导线之间的平衡电流-相位关系表现出了很强的$4pi周期。
We study the Josephson effect in a trijunction formed by two topological superconductor (TS) wires and a conventional $s$-wave superconductor. Using a boundary Green's function formalism, analytical results for the current-phase relation are obtained in various limiting cases by modeling the TS wires via the low-energy limit of a Kitaev chain. We show that Josephson transport critically depends on the spin canting angle $\theta$ between the boundary spin polarizations of the TS wires, which in turn suggests that the spin structure of Majorana states can be accessed through supercurrent measurements. We also extend the boundary Green's function approach to a more microscopic spinful wire model and thereby compute the dependence of $\theta$ on experimentally accessible parameters such as the Zeeman field and/or the chemical potential. Furthermore, we show that the equilibrium current-phase relation between both TS wires exhibits a robust $4\pi$-periodicity since the conventional superconducting lead effectively locks the fermion parity of the trijunction.