Josephson diode effect in multichannel Rashba nanowires: Role of inter-subband coupling

Ardamon Sten; Sudeep Kumar Ghosh

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arXiv · 2604.19385

Josephson diode effect in multichannel Rashba nanowires: Role of inter-subband coupling

Ardamon Sten·Sudeep Kumar Ghosh

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Abstract

The Josephson diode effect (JDE) has attracted significant attention for enabling directional, dissipationless supercurrents, positioning Josephson junctions as promising building blocks for next-generation quantum devices. Hybrid semiconductor-superconductor nanowires provide an experimentally accessible platform for realizing the JDE and hosting Majorana bound states. However, most theoretical treatments assume the single-channel limit, whereas realistic nanowire devices are inherently multichannel due to transverse confinement. Here, we investigate the JDE in multichannel Rashba nanowire Josephson junctions, focusing on the role of inter-subband coupling. We show that subband hybridization qualitatively modifies both the topological phase diagram and the JDE response of the device. In contrast to the single-channel case, the topological phase is confined to a finite window of Zeeman fields, within which Majorana bound states strongly enhance the diode efficiency. Inter-subband coupling also enables a finite JDE even when the Zeeman field is aligned along the spin-orbit direction -- a mechanism absent in independent-channel and strictly one-dimensional nanowire systems. Furthermore, inter-subband coupling enhances spectral asymmetry and significantly increases the diode efficiency compared to single-channel junctions. These results identify inter-subband hybridization as a key ingredient for realizing and optimizing nonreciprocal superconducting transport in experimentally relevant hybrid nanowire Josephson junctions.

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Ardamon Sten, Sudeep Kumar Ghosh. 2026-04-27. Josephson diode effect in multichannel Rashba nanowires: Role of inter-subband coupling. https://arxiv.org/abs/2604.19385

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