Hanbury Brown and Twiss noise correlations in a topological superconductor beam splitter
Hanbury Brown and Twiss noise correlations in a topological superconductor beam splitter
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DOI：
10.1103/physrevb.95.054514
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发表时间：
2016-11
影响因子：
3.7
通讯作者：
T. Jonckheere;J. Rech;A. Zazunov;R. Egger;T. Martin
中科院分区：
文献类型：
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作者：
T. Jonckheere;J. Rech;A. Zazunov;R. Egger;T. Martin
我们研究了Hanbury-Brown和Twiss电流的交叉关联在一个三端结的中心拓扑超导体（TS）纳米线，轴承Majorana束缚态在其两端，连接到两个正常的引线。依赖于非微扰绿色函数形式主义，我们的计算使我们能够提供的电流和它们的相关性在子间隙电压的解析表达式，同时也给出了精确的数值计算结果有效的任意外部偏压。我们表明，当正常的引线偏置在电压V1和V2小于差距，电流互相关的符号是由−sgn（V1 V2）。特别是，这导致相反电压的正互相关，与标准超导体的行为形成鲜明对比，这提供了在TS边缘存在马约拉纳零模的直接证据。我们进一步扩展我们的结果，不同的TS的长度（导致重叠的马约拉纳束缚态），以及它的化学势（驾驶它远离半填充），概括的边界TS绿色功能，这些情况下。在相反偏置电压sgn（V1 V2）=−1的情况下，驱动TS线通过拓扑转变导致电流互相关的符号变化，提供了马约拉纳束缚态物理学的另一个特征。
We study Hanbury-Brown and Twiss current cross-correlations in a three-terminal junction where a central topological superconductor (TS) nanowire, bearing Majorana bound states at its ends, is connected to two normal leads. Relying on a non-perturbative Green function formalism, our calculations allow us to provide analytical expressions for the currents and their correlations at subgap voltages, while also giving exact numerical results valid for arbitrary external bias. We show that when the normal leads are biased at voltages V1 and V2 smaller than the gap, the sign of the current cross-correlations is given by −sgn(V1V2). In particular, this leads to positive cross-correlations for opposite voltages, a behavior in stark contrast with the one of a standard superconductor, which provides a direct evidence of the presence of the Majorana zero-mode at the edge of the TS. We further extend our results, varying the length of the TS (leading to an overlap of the Majorana bound states) as well as its chemical potential (driving it away from half-filling), generalizing the boundary TS Green function to those cases. In the case of opposite bias voltages, sgn(V1V2)=−1, driving the TS wire through the topological transition leads to a sign change of the current cross-correlations, providing yet another signature of the physics of the Majorana bound state.