Resonant suppression of the π-type Josephson component in a Kitaev-ladder junction
Abstract
We investigate Josephson transport through a finite normal segment connecting two Kitaev-ladder superconductors and show that discrete-level detuning controls the sign of the equilibrium Josephson coupling through a branch-selection mechanism. Away from resonance, detuning separates two competing low-energy branches, allowing inter-leg hybridization to clamp the $0$-phase-favoring branch while leaving the π-favoring branch dispersive. The resulting negative first harmonic evolves from a branch-switching response at weak coupling into a smooth π-junction regime. At resonance the two clamping thresholds coincide, so the finite interval in which only one branch remains dispersive disappears. Once the inter-leg coupling exceeds the resonant clamping threshold, both low-energy branches become independent of the Josephson phase. The remaining finite-energy states then generate a $0$-type Josephson coupling. At ϕ=π, the helicity decomposition yields an exact clamping identity for arbitrary finite normal-segment length. Within the controlled sweet-point finite-segment theory, serial propagation fixes the off-resonant fourth-order harmonic to be negative, whereas an isolated resonance leaves a positive residual harmonic within the resonant clamping regime. Numerical calculations demonstrate that the resonance-induced suppression persists away from the solvable phase choice. Thus normal-level resonance does not merely enhance Josephson transmission; it changes which low-energy branches contribute to the Josephson coupling.
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BibTeX
@misc{xie2026resonant,
title = {{Resonant suppression of the $π$-type Josephson component in a Kitaev-ladder junction}},
author = {Cheng-Rong Xie and Hiroki Tsuchiura and Yukio Tanaka},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.23875},
eprint = {2610.23875},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.23875},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Resonant suppression of the π-type Josephson component in a Kitaev-ladder junction
AU - Cheng-Rong Xie
AU - Hiroki Tsuchiura
AU - Yukio Tanaka
PY - 2026
DA - 2026/10/01
PB - arXiv
DO - 10.48550/arxiv.2610.23875
UR - https://arxiv.org/abs/2610.23875
AB - We investigate Josephson transport through a finite normal segment connecting two Kitaev-ladder superconductors and show that discrete-level detuning controls the sign of the equilibrium Josephson coupling through a branch-selection mechanism. Away from resonance, detuning separates two competing low-energy branches, allowing inter-leg hybridization to clamp the $0$-phase-favoring branch while leaving the π-favoring branch dispersive. The resulting negative first harmonic evolves from a branch-switching response at weak coupling into a smooth π-junction regime. At resonance the two clamping thresholds coincide, so the finite interval in which only one branch remains dispersive disappears. Once the inter-leg coupling exceeds the resonant clamping threshold, both low-energy branches become independent of the Josephson phase. The remaining finite-energy states then generate a $0$-type Josephson coupling. At ϕ=π, the helicity decomposition yields an exact clamping identity for arbitrary finite normal-segment length. Within the controlled sweet-point finite-segment theory, serial propagation fixes the off-resonant fourth-order harmonic to be negative, whereas an isolated resonance leaves a positive residual harmonic within the resonant clamping regime. Numerical calculations demonstrate that the resonance-induced suppression persists away from the solvable phase choice. Thus normal-level resonance does not merely enhance Josephson transmission; it changes which low-energy branches contribute to the Josephson coupling.
ER -