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arXiv · 2608.19312

Interferometric Signatures of Zero Modes in Fractional Quantum Hall-Superconductor Heterostructures

Junyi Cao·Ramanjit Sohal·Angela Kou·Eduardo Fradkin
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Abstract

Fractional quantum Hall-superconductor (FQH-SC) heterostructures are predicted to host defect-bound parafermion zero modes (PZMs). We propose two related configurations to probe their fusion structure. In a Josephson junction coupled to a single quantum point contact (QPC), quasiparticle tunneling switches the defect fusion channel, producing stochastic transitions between branches of the fractional Josephson spectrum. Embedding the junction in a two-QPC Fabry-P\'{e}rot interferometer provides a complementary probe. Weak zero mode tunneling produces fusion-channel-dependent interference while strong tunneling makes the interferometer probe a superposition of fusion channels and strongly suppresses the signal: in the topological limit it vanishes exactly, revealing the defects' non-Abelian nature even when the parent FQH state is Abelian.

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Junyi Cao, Ramanjit Sohal, Angela Kou, Eduardo Fradkin. 2026-08-19. Interferometric Signatures of Zero Modes in Fractional Quantum Hall-Superconductor Heterostructures. https://arxiv.org/abs/2608.19312

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