论文标题
原子量尺度上的光子辅助隧道：探测来自Yu-Shiba-Rusinov状态的Andreev反射
Photon-assisted tunneling at the atomic scale: Probing resonant Andreev reflections from Yu-Shiba-Rusinov states
论文作者
论文摘要
跨超导连接的隧道通过多种过程进行，这些过程通过多个Andreev反射传递单电子，库珀对，甚至大量的电子。长期以来，光子辅助隧道与古老的Tien-Gordon模型相结合，一直是识别超导体之间的隧道过程的强大工具。在这里，我们通过将带有超导尖端的扫描隧道显微镜暴露于微波辐射中，探测包括杂质诱导的Yu-Shiba-Rusinov（YSR）状态的隧道连接。我们发现，一个简单的Tien-Gordon描述将单电子和库珀对的隧道描述为裸露的基板，但通过resonant Andreev Refflections通过YSR状态分解以通过YSR状态进行隧道。我们开发了改进的理论描述，这与数据非常吻合。我们的结果建立了光子辅助隧道作为在原子量表上分析隧道过程的强大工具，这对于非常规和拓扑超导体应该特别有用。
Tunneling across superconducting junctions proceeds by a rich variety of processes, which transfer single electrons, Cooper pairs, or even larger numbers of electrons by multiple Andreev reflections. Photon-assisted tunneling combined with the venerable Tien-Gordon model has long been a powerful tool to identify tunneling processes between superconductors. Here, we probe superconducting tunnel junctions including an impurity-induced Yu-Shiba-Rusinov (YSR) state by exposing a scanning tunneling microscope with a superconducting tip to microwave radiation. We find that a simple Tien-Gordon description describes tunneling of single electrons and Cooper pairs into the bare substrate, but breaks down for tunneling via YSR states by resonant Andreev reflections. We develop an improved theoretical description which is in excellent agreement with the data. Our results establish photon-assisted tunneling as a powerful tool to analyze tunneling processes at the atomic scale which should be particularly informative for unconventional and topological superconductors.
