Mathematical and Theoretical Physics Seminar (MTPS)

Stephan Haas (Physics & Astronomy, University of Southern California, United States)

Superconductivity and Plasmonic Excitations in Topological Quantum Systems

Abstract: We explore collective excitations in topological quantum systems. Specifically, we analyze inhomogeneous superconducting phases induced by an attractive U Hubbard interaction, revealing unique effects on corners and edges in lattices with open boundaries. Notably, at half filling, the corner site's superconducting transition temperature can surpass that of the bulk, creating a novel proximity effect. Furthermore, we use the random phase approximation to unveil edge plasmonic excitations in topological insulators. We explore the impact of long-range Coulomb interactions on the many-body excitation spectrum of topological insulators, observing strongly localized topological plasmons. This seminar also highlights the influence of effective Coulomb interactions on plasmonic modes and suggests experimental verifications through external modifications like dielectric screening and applied electric fields.