Nonreciprocal Superconducting Transport from Chiral Edge States

Nonreciprocal superconducting transport enables dissipationless rectification and has attracted considerable interest, yet its microscopic origin is typically sought in bulk electronic states. Here, we show that boundary-controlled chiral edge states in topological systems provide a simple yet largely overlooked mechanism for nonreciprocal superconducting transport. Focusing on chiral kagome antiferromagnets, we demonstrate that out-of-plane spin canting or spin-orbit coupling opens a high-Chern-number bulk gap, giving rise to multiple chiral edge modes. Strikingly, sublattice-dependent boundary termination selects a single-valley character for the edge states, leading to asymmetric edge spectra at opposite edges. This boundary asymmetry directly yields observable nonreciprocal signatures in Josephson junctions oriented transverse to the edges, including asymmetric Andreev spectra, Josephson diode effect, and anomalous Fraunhofer interference patterns. These findings broaden the microscopic understanding of superconducting nonreciprocity and highlight boundary engineering as a tunable route toward superconducting diode devices.