A magnetic impurity coupled to a superconductor gives rise to a Yu-Shiba-Rusinov (YSR) state inside the superconducting energy gap. With increasing exchange coupling the excitation energy of this state eventually crosses zero and the system switches to a YSR ground state with bound quasiparticles screening the impurity spin by ħ/2. Here we explore indium arsenide (InAs) nanowire double quantum dots tunnel coupled to a superconductor and demonstrate YSR screening of spin-1/2 and spin-1 states. Gating the double dot through nine different charge states, we show that the honeycomb pattern of zero-bias conductance peaks, archetypal of double dots coupled to normal leads, is replaced by lines of zero-energy YSR states. These enclose regions of YSR-screened dot spins displaying distinctive spectral features, and their characteristic shape and topology change markedly with tunnel coupling strengths. We find excellent agreement with a simple zero-bandwidth approximation, and with numerical renormalization group calculations for the two-orbital Anderson model.

中文翻译：

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Yu-Shiba-Rusinov筛选双量子点中的自旋。

耦合到超导体的磁性杂质会在超导能隙内产生Yu-Shiba-Rusinov（YSR）状态。随着交换耦合的增加，该状态的激发能最终越过零，系统切换到YSR基态，结合的准粒子将杂质自旋滤除了/ 2。在这里，我们探索耦合到超导体的砷化铟（InAs）纳米线双量子点隧道，并演示了自旋1/2和自旋1状态的YSR筛选。通过九个不同的电荷状态对双点进行选通，我们显示零偏压电导峰的蜂窝模式（双点原型与正常引线耦合）被零能量YSR状态的线替代。这些包围YSR筛选的点旋转的区域显示出独特的光谱特征，它们的特征形状和拓扑随着隧道耦合强度的变化而显着变化。我们找到了一个简单的零带宽近似值，并且对两轨道安德森模型进行了数值归一化组计算，发现了极好的一致性。