【时  间】2024年5月23日（周四） 上午 10:00

【地  点】量子院 526会议室

【主  持】徐洪起 半导体自旋与拓扑量子计算团队 首席科学家

【题  目】Topological Superfluid Responses of Superconducting Dirac Semimetals

【摘  要】In this talk, He shows that topological constraints do not only dictate the geometric part of the superfluid stiffness, as it has been recently discussed, but can also govern the total superfluid stiffness. By introducing a general adiabatic approach for superfluid responses, He will demonstrate such a possibility by proving that the stiffness of a superconducting Dirac cone in two dimensions (2D) is proportional to its topological charge. By relying on the emergent Lorentz invariance of Dirac electrons, He will further discuss that the superfluid stiffness and the Josephson quantum capacitance can be unified in these systems. In addition, He will show that these topological responses persist upon effecting strain, are resilient against weak disorder, and can be experimentally controlled via a Zeeman field. Remarkably, the nonuniversal topological quantization of these two superfluid responses, yet implies the universal topological quantization of the admittance modulus of the superconducting Dirac system in units of conductance. The here-coined quantum admittance effect arises when embedding the superconducting Dirac system in an ac electrical circuit with a frequency tuned at the absorption edge. These findings can be in principle experimentally observed in graphene-superconductor hybrids.

【报告人简介】Panagiotis Kotetes is since the beginning of 2019 an Associate Professor at the Institute of Theoretical Physics of the Chinese Academy of Sciences in Beijing. During the years 2015-2018 he served as a postdoctoral researcher at the Niels Bohr Institute of the University of Copenhagen. Before that, he completed a postdoctoral appointment at the Karlsruhe Institute of Technology, where he worked for five years. Panagiotis carried out his Diploma, Masters and Ph.D. studies at the National Technical Universit.