Emergent topology by Landau level mixing in quantum Hall-superconductor nanostructures

Abstract: We demonstrate the emergence of novel topological phases in quantum Hall-superconductor hybrid systems driven by Landau level mixing and spin-orbit interactions. Focusing on a narrow superconducting stripe atop a two-dimensional electron gas, we identify regimes where the hybridization of the chiral Andreev states at each side of the stripe leads to different phases beyond the long sought $p$-wave superconducting one. These topological phases exhibit distinctive transport signatures, including quantized nonlocal conductance arising from electron cotunneling at filling factor $\nu=1$, which can coexist with quantized crossed Andreev reflection at $\nu=2$. A combination of numerical simulations and effective modelling reveals the role of spin-orbit coupling and stripe geometry in controlling these transitions. Our findings suggest new strategies for realizing and detecting topology in proximized quantum Hall devices.