Long-lived Andreev states as evidence for protected hinge modes in a bismuth nanoring Josephson junction
Long-lived Andreev states as evidence for protected hinge modes in a bismuth nanoring Josephson junction
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DOI：
10.1038/s41567-022-01858-8
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发表时间：
2023-01-16
期刊：
影响因子：
19.6
通讯作者：
Gueron, S.
中科院分区：
文献类型：
--
作者：
Bernard, A.;Peng, Y.;Gueron, S.
二阶拓扑绝缘体的特征在于螺旋形的、非自旋简并的一维态，其沿沿着相对的晶体铰链运行，没有反向散射。因此，注入超导对需要将库珀对分裂成两个螺旋度相反的螺旋安德烈耶夫态家族，每个铰链处一个。在这里，我们通过测量和分析铋的晶体纳米环的开关超电流统计提供了这种分离的证据。使用一个唯象模型的两个螺旋Andreev铰链模式，我们发现，对放松的速度相当于个人准粒子，在非拓扑系统的对松弛快得多。这构成了拓扑螺旋铰链空间分离的独特迹象。二阶拓扑绝缘体的特征是位于晶体铰链处的螺旋一维状态。通过这样的系统运行一个超电流现在被证明会导致长寿命的激发Andreev对，因为它们沿着具有相反螺旋度的铰链分离。
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.Second-order topological insulators feature helical one-dimensional states located at crystal hinges. Running a supercurrent through such systems is now shown to lead to long-lived excited Andreev pairs due to their separation along hinges with opposite helicity.