Josephson current and noise at a superconductor/quantum-spin-Hall-insulator/superconductor junction
Josephson current and noise at a superconductor/quantum-spin-Hall-insulator/superconductor junction
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DOI：
10.1103/physrevb.79.161408
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发表时间：
2009-04-01
影响因子：
3.7
通讯作者：
Kane, C. L.
中科院分区：
文献类型：
--
作者：
Fu, Liang;Kane, C. L.
我们研究了量子自旋霍尔绝缘体的边缘态介导的超导体之间的结。我们发现，这样的结表现出分数约瑟夫森效应，其中的电流相位关系具有4 π而不是2 π的周期性。这种效应是超导结中费米子宇称（电子数模2）守恒的结果，与量子自旋霍尔绝缘体的Z（2）拓扑结构密切相关。非弹性过程违反了费米子宇称守恒，导致了平衡态超流中的电报噪声。我们预测，由于这些过程的低频噪声随温度T呈指数发散T -> 0。HgCdTe量子威尔斯阱的可能实验将被讨论。
We study junctions between superconductors mediated by the edge states of a quantum-spin-Hall insulator. We show that such junctions exhibit a fractional Josephson effect, in which the current phase relation has a 4 pi rather than a 2 pi periodicity. This effect is a consequence of the conservation of fermion parity-the number of electron mod 2-in a superconducting junction and is closely related to the Z(2) topological structure of the quantum-spin-Hall insulator. Inelastic processes, which violate the conservation of fermion parity, lead to telegraph noise in the equilibrium supercurrent. We predict that the low-frequency noise due these processes diverges exponentially with temperature T as T -> 0. Possible experiments on HgCdTe quantum wells will be discussed.