Topological Andreev bands in three-terminal Josephson junctions
Topological Andreev bands in three-terminal Josephson junctions
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三端约瑟夫森结中的拓扑安德烈夫能带
DOI：
10.1103/physrevb.96.161406
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发表时间：
2017
影响因子：
3.7
通讯作者：
Levchenko, Alex
中科院分区：
文献类型：
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作者：
Xie, Hong-Yi;Vavilov, Maxim G.;Levchenko, Alex
研究了三端约瑟夫森结中亚带隙Andreev束缚态的能带拓扑。我们仔细检查的对称性约束的散射矩阵在正常区域连接超导导线，使拓扑节点的Andreev状态的频谱。当散射矩阵具有时间反演对称性时，差距闭合发生在特殊的稳定点，这些点在拓扑上是平凡的，因为它们携带消失的Berry通量。相反，对于时间反演的情况下，我们发现拓扑单极的Berry曲率和相应的相变状态之间的不同陈数。后者由散射矩阵的结构控制，该散射矩阵可以由穿过三端子几何结构中的结区域的磁通量来调谐。该系统的拓扑制度可以确定由非局部电导量子化，我们计算明确的散射矩阵的一个特定的参数化的情况下，每个水库是由一个单一的通道连接。
We study the emergent band topology of subgap Andreev bound states in the three-terminal Josephson junctions. We scrutinize the symmetry constraints of the scattering matrix in the normal region connecting superconducting leads that enable the topological nodal points in the spectrum of Andreev states. When the scattering matrix possesses time-reversal symmetry, the gap closing occurs at special stationary points that are topologically trivial as they carry vanishing Berry fluxes. In contrast, for the time-reversal broken case we find topological monopoles of the Berry curvature and corresponding phase transition between states with different Chern numbers. The latter is controlled by the structure of the scattering matrix that can be tuned by a magnetic flux piercing through the junction area in a three-terminal geometry. The topological regime of the system can be identified by nonlocal conductance quantization that we compute explicitly for a particular parametrization of the scattering matrix in the case where each reservoir is connected by a single channel.