Condensed Matter Seminar: Topological symplectic Kondo effect

The topological Kondo effect describes the stable, strongly coupled, non-Fermi liquid state obtained by screening a topological quantum dot, a so-called Majorana Cooper pair box, by means of external metallic leads. The symmetry group describing this exotic Kondo effect is the orthogonal group of rotations of real Majorana fermions. In this talk, I am going to present a symplectic topological Kondo effect, which, crucially, does not rely on the presence of Majorana modes. As I present in detail, this system can be implemented by coupling leads to a quantum dot consisting of a floating conventional s-wave superconductor coupled to spinful fermionic zero modes, as obtained e.g., in arrays of 1D topological insulators. Using conformal field theory, a mapping to a dual theory at strong coupling, and Bethe Ansatz calculations, I will show that this model harbors signatures of emergent anyonic excitations, including Fibonacci anyons, depending on the number of external leads. Importantly, the non-trivial physics is stable to anisotropies in the coupling to different leads. Experimental consequences such as the scaling of transconductance and susceptibility are discussed.