Single fermion manipulation via superconducting phase differences in multiterminal Josephson junctions
Single fermion manipulation via superconducting phase differences in multiterminal Josephson junctions
复制标题
通过多端约瑟夫森结中的超导相位差操纵单费米子
DOI：
10.1103/physrevb.90.155450
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发表时间：
2014
影响因子：
3.7
通讯作者：
A. Akhmerov
中科院分区：
文献类型：
--
作者：
B. Heck;S. Mi;A. Akhmerov
我们展示了如何利用约瑟夫森结中的超导相位差来分裂其能级的克莱默简并性并消除与时间反转对称性相关的所有特性。众所周知，超导相位差在两端短约瑟夫森结中是无效的，无论结结构如何，诱导的克莱默简并分裂都会受到抑制，并且基态费米子宇称必须保持均匀，因此受保护的零能量安德烈夫能级交叉可能永远不会出现。我们的主要结果是，通过使用多端约瑟夫森结可以完全避免这些限制。在那里，克莱默简并破缺变得与超导能隙相当，并且应用相位差可能导致基态费米子宇称从偶数变为奇数。我们证明了费米子奇偶校验开关出现的必要条件是结点处存在“离散涡旋”：即超导相位超前2π的情况。我们的方法提供了创建马约拉纳束缚态以及自旋操纵的策略。我们的建议可以使用任何低密度、高自旋轨道材料（例如 InAs 量子阱）来实现，并且可以使用标准工具进行检测。
We show how the superconducting phase difference in a Josephson junction may be used to split the Kramers degeneracy of its energy levels and to remove all the properties associated with time-reversal symmetry. The superconducting phase difference is known to be ineffective in two-terminal short Josephson junctions, where irrespective of the junction structure the induced Kramers degeneracy splitting is suppressed and the ground state fermion parity must stay even, so that a protected zero-energy Andreev level crossing may never appear. Our main result is that these limitations can be completely avoided by using multiterminal Josephson junctions. There the Kramers degeneracy breaking becomes comparable to the superconducting gap, and applying phase differences may cause the change of the ground state fermion parity from even to odd. We prove that the necessary condition for the appearance of a fermion parity switch is the presence of a “discrete vortex” in the junction: the situation when the phases of the superconducting leads wind by 2?. Our approach offers strategies for creation of Majorana bound states as well as spin manipulation. Our proposal can be implemented using any low density, high spin-orbit material such as InAs quantum wells, and can be detected using standard tool.