Topological Superconductivity in a Planar Josephson Junction
Topological Superconductivity in a Planar Josephson Junction
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DOI：
10.1103/physrevx.7.021032
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发表时间：
2017-05-30
影响因子：
12.5
通讯作者：
Halperin, Bertrand I.
中科院分区：
文献类型：
--
作者：
Pientka, Falko;Keselman, Anna;Halperin, Bertrand I.
我们考虑一种二维电子气体，并通过两个超导导线接触，形成了约瑟夫森连接，并通过两个超导导线接触。我们表明，在面积内采地的存在下，两个超导体之间的准二维区域可以支撑拓扑超导相位，该拓扑超导相位在其末端托管Majoragennagand状态。我们研究系统的相图作为Zeeman场的函数以及两个超导体之间的相位差（被视为外部控制参数）。值得注意的是，在PI的相位差异，对于几乎任何Zeeman场和化学势的值，都可以获得拓扑相。在该相位不受外部控制的设置中，我们发现当Zeeman字段变化时，系统会经历一阶拓扑相变。在过渡时，基态的相位差异从接近零的值突然变化，该值在该值是微不足道的，到接近P的值，该值是拓扑的。通过连接点的临界电流在临界齐曼场表现出急切的最小值，因此是过渡的自然诊断。我们指出，在镜面反射下存在对称性的情况下，随后是时间逆转，系统属于较高的对称类别，并且相图作为相位差的函数，而Zeeman场则变得更丰富。
We consider a two-dimensional electron gas with strong spin-orbit coupling contacted by two superconducting leads, forming a Josephson junction. We show that in the presence of an in-plane Zeeman field, the quasi-one-dimensional region between the two superconductors can support a topological superconducting phase hosting Majorana bound states at its ends. We study the phase diagram of the system as a function of the Zeeman field and the phase difference between the two superconductors (treated as an externally controlled parameter). Remarkably, at a phase difference of pi, the topological phase is obtained for almost any value of the Zeeman field and chemical potential. In a setup where the phase is not controlled externally, we find that the system undergoes a first-order topological phase transition when the Zeeman field is varied. At the transition, the phase difference in the ground state changes abruptly from a value close to zero, at which the system is trivial, to a value close to p, at which the system is topological. The critical current through the junction exhibits a sharp minimum at the critical Zeeman field and is therefore a natural diagnostic of the transition. We point out that in the presence of a symmetry under a mirror reflection followed by time reversal, the system belongs to a higher symmetry class, and the phase diagram as a function of the phase difference and the Zeeman field becomes richer.