Spånslätt Christian, Ardonne Eddy, Budich Jan Carl, Hansson T H
Department of Physics, Stockholm University, SE-106 91 Stockholm, Sweden.
J Phys Condens Matter. 2015 Oct 14;27(40):405701. doi: 10.1088/0953-8984/27/40/405701. Epub 2015 Sep 24.
We theoretically investigate Josephson junctions with a phase shift of π in various proximity induced one-dimensional superconductor models. One of the salient experimental signatures of topological superconductors, namely the fractionalized 4π periodic Josephson effect, is closely related to the occurrence of a characteristic zero energy bound state in such junctions. We make a detailed analysis of a more general type of π-junctions coined 'phase winding junctions' where the phase of the order parameter rotates by an angle π while its absolute value is kept finite. Such junctions have different properties, also from a topological viewpoint, and there are no protected zero energy modes. We compare the phenomenology of such junctions in topological (p-wave) and trivial (s-wave) superconducting wires, and briefly discuss possible experimental probes. Furthermore, we propose a topological field theory that gives a minimal description of a wire with defects corresponding to π-junctions. This effective theory is a one-dimensional version of similar theories describing Majorana bound states in half-vortices of two-dimensional topological superconductors.
我们从理论上研究了在各种近邻诱导的一维超导模型中具有π相移的约瑟夫森结。拓扑超导体的一个显著实验特征，即分数化的4π周期约瑟夫森效应，与此类结中特征零能束缚态的出现密切相关。我们对一种更一般类型的π结，即“相位缠绕结”进行了详细分析，在这种结中，序参量的相位旋转了一个π角，而其绝对值保持有限。从拓扑角度来看，此类结也具有不同的性质，并且不存在受保护的零能模式。我们比较了此类结在拓扑（p波）和平凡（s波）超导线中的现象学，并简要讨论了可能的实验探测方法。此外，我们提出了一种拓扑场论，它给出了对具有对应于π结的缺陷的导线的最小描述。这种有效理论是描述二维拓扑超导体半涡旋中马约拉纳束缚态的类似理论的一维版本。
