法国巴黎-萨克雷大学S. Guéron小组的研究发现了长寿命Andreev态证实了铋纳米环约瑟夫森结的受保护晶链模式。相关论文于2023年1月16日发表在《自然—物理学》杂志上。

在这里，该团队通过测量和分析铋晶体纳米环的开关超电流统计数据，为这种分离提供了证据。基于两螺旋Andreev晶链模式的唯象模型，研究发现，形成了与单个准粒子相当的速率驰豫，与非拓扑系统快得多的库仑对驰豫。这构成了拓扑螺旋晶链空间分离的独特标志。

据介绍，二阶拓扑绝缘体的特征是螺旋的，非自旋简并一维状态沿相反的晶体铰链运行，没有反向散射。因此，注入超导对需要将库珀对分裂为两族螺旋性相反的Andreev态，每个晶链上各有一个。

附：英文原文

Title: Long-lived Andreev states as evidence for protected hinge modes in a bismuth nanoring Josephson junction

Author: Bernard, A., Peng, Y., Kasumov, A., Deblock, R., Ferrier, M., Fortuna, F., Volkov, V. T., Kasumov, Yu. A., Oreg, Y., von Oppen, F., Bouchiat, H., Guron, S.

Issue&Volume: 2023-01-16

Abstract: Second-order topological insulators are characterized by helical, non-spin-degenerate one-dimensional states running along opposite crystal hinges with no backscattering. Injecting superconducting pairs therefore entails splitting Cooper pairs into two families of helical Andreev states of opposite helicity, one at each hinge. Here we provide evidence for such separation via the measurement and analysis of the switching supercurrent statistics of a crystalline nanoring of bismuth. Using a phenomenological model of two helical Andreev hinge modes, we find that pairs relax at a rate comparable to individual quasiparticles, in contrast to the much faster pair relaxation of non-topological systems. This constitutes a unique telltale sign of the spatial separation of topological helical hinges.

DOI: 10.1038/s41567-022-01858-8

Source: https://www.nature.com/articles/s41567-022-01858-8