Current-driven reduction of topological protection in multichannel superconductors

TL;DR

This paper studies how a finite charge current affects the topological phases in a multichannel superconducting ladder, revealing the fragility of topological protection under current influence.

Contribution

It introduces an effective Hamiltonian depending on quasiparticle momentum to analyze current-induced topological phase reduction in superconducting ladders.

Findings

Finite current flux destabilizes the two-mode topological phase.

Bulk topological invariants and entanglement diagnostics reveal fragility.

Framework established for understanding current effects on topological protection.

Abstract

We investigate the robustness of topological phases in a Kitaev ladder composed of two coupled superconducting chains under the perturbing influence of a finite charge current. By introducing an effective Hamiltonian depending on the quasiparticle momentum induced by the current, we show that the two-mode topological phase, present in the isolated ladder, is fragile against a finite current flux. To characterize this behavior, we combine bulk topological invariants with real-space diagnostics, including the edge-edge quantum conditional mutual information Iee, which provides an entanglement-based signature of topological order. Our results provide an effective framework to describe how current injection and measurement processes can affect topological protection in superconducting nanostructures.