Title: Inducedsuperconductivity in a fractional quantum Hall edge

Lecturer: Dr' Yuval Ronen – Harvard university

Abstract: Topologicalsuperconductivity, realized as anintrinsic material property or as an emerging property of a hybrid structure, representsa phase of matter where topological constraints and superconductivity coexist.The exchange-statistics (braiding) of its quasiparticles is not bosonic norfermionic but is rather non-Abelian. Due to their exchange-statistics as wellas non-locality these excitations offer a promising route towardsfault-tolerant quantum computation. The simplest non-Abelian anyon is the Majoranazero mode with an Ising order. However, since braiding of Ising anyons does notoffer a universal quantum gate set, theoretical studies have introduced Parafermionzero modes (PZM), an array of which supports universal topological quantum computation.The primary route to synthesize PZMs involves inducing superconductivity on afractional quantum Hall effect (FQHE) edge.

In this talk, I will introduce high-qualitygraphene-based van der Waals devices with narrow superconducting electrode(NbN), in which superconductivity and robust FQHE coexist. We find crossedAndreev reflection (CAR) across the superconductor separating twocounterpropagating FQHE edges. Our observed CAR probability of the integeredges is insensitive to magnetic field, temperature, and filling, therebyproviding evidence for spin-orbit coupling inherited from NbN enabling thepairing of the otherwise spin-polarized edges. FQHE edges notably exhibit a CARprobability higher than that of integer edges once fully developed. This FQHE CARprobability remains nonzero down to our lowest accessible temperature,suggesting superconducting pairing of fractional charges. These results providea route to realize novel topological superconducting phases with universalbraiding statistics in FQHE–superconductor hybrid devices based on graphene andNbN.