Bound states in superconductors revealed by Josephson tunneling

超导基态与纳米级交换或库仑势的局部竞争开辟了一个极其丰富的物理学领域，包括Shiba或新颖的majorana型态。讨论了后者作为实现容错量子计算的有希望的例子。通过统一我们两个小组的实验方法，这个联合提议旨在解决关于磁性和超导性局部相互作用的基本问题。特别是，我们正在寻找I型超导体上的一维和二维磁性纳米结构的拓扑状态的特征。柏林团队在扫描隧道显微镜/光谱学（STM/STS）研究超导衬底上磁性纳米结构的束缚态方面有着丰富的经验。格勒诺布尔小组在量子纳米电子学和相关输运测量方面的专业知识是非常互补的。这将使两个小组能够共同实施扫描约瑟夫森隧道显微镜技术，从而揭示单磁性原子、少原子团簇、纳米线和磁性分子周围超导有序参数在原子尺度上的变化。我们将进一步将微波场耦合到扫描隧道显微镜中，允许同时测量夏皮罗步长和高分辨率STM/STS。从局域态密度、约瑟夫森临界电流和微波响应的综合知识中，我们将寻求超导体中拓扑态的证据。

The local competition of the superconducting ground state with a nanoscale exchange or Coulomb potential opens an extremely rich field of physics, including Shiba or novel Majorana-type states. The latter are discussed as promising examples for the realization of fault-tolerant quantum computing. By unifying the experimental approaches from our two groups, this joint proposal aims at resolving fundamental questions about the local interaction of magnetism and superconductivity. In particular, we are seeking for signatures of topological states in one- and two-dimensional magnetic nanostructures on type I superconductors. The Berlin group has strong experience in Scanning Tunneling Microscopy/Spectroscopy (STM/STS) of bound states around magnetic nanostructures on superconducting substrates. The Grenoble group's expertise in quantum nano-electronics and related transport measurements is very complementary. This will enable the two groups to jointly implement the technique of Scanning Josephson Tunneling Microscopy and thereby reveal the variations in the superconducting order parameter at the atomic scale around single magnetic adatoms, few-atom clusters, nanowires and magnetic molecules. We will further couple microwave fields into the Scanning Tunneling Microscope, allowing for simultaneous measurements of Shapiro steps and high-resolution STM/STS. From the combined knowledge of the local density of states, the Josephson critical current and the microwave response, we will seek for evidence of topological states in superconductors.