Loss and decoherence of the Chiral Andreev edge states in the quantum Hall regime

We explore graphene samples in a contact with a type II superconductor at high magnetic fields. In the quantum Hall regime, we observe signatures of the chiral Andreev edge states (CAES) formed along the interface with the superconductor. These single particle states consist of electrons and holes hybridized in a fashion similar to Majorana fermions. Qualitatively, the CAES can be visualized as a result of multiple Andreev reflections of a single electron/hole skipping along the superconducting interface. We find that the signatures of the CAES are found to be sensitive to the configuration of vortices in the superconductor. We find that the probability of Andreev conversion of electrons to holes follows an unexpected but clear trend: the dependencies on temperature and magnetic field are nearly decoupled. We interprete these trends in terms of CAES loss and decoherence.