Time-reversal invariant vortex in topological superconductors and gravitational $\mathbb{Z}_2$ topology

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Hauptverfasser: Yamamoto, Kazuki, Kan, Naoto, Fukaya, Hidenori
Format: Preprint
Veröffentlicht: 2025
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author Yamamoto, Kazuki
Kan, Naoto
Fukaya, Hidenori
author_facet Yamamoto, Kazuki
Kan, Naoto
Fukaya, Hidenori
contents We study a time-reversal invariant vortex, namely a spin vortex, in helical superconductors by focusing on its emergent gravitational structure. The topology of the time-reversal invariant vortex is classified by a $\mathbb{Z}_2$ invariant: helical Majorana zero modes appear at the vortex core when the winding number is odd, while no such zero modes exist when it is even. We provide a formal mapping to the theory of gravity to describe this $\mathbb{Z}_2$ topological structure. Identifying a superconducting order parameter as a vielbein in the theory of gravity, we explicitly convert the Bogoliubov-de-Genne Hamiltonian into the Dirac Hamiltonian coupled to a nontrivial gravitational field. Then we find that a gravitational curvature is induced at the vortex core, with its total flux quantized in integer multiples of $π$, reflecting the $\mathbb{Z}_2$ topology. Although the curvature vanishes everywhere except at the vortex core, the energy spectrum remains sensitive to the total curvature flux, owing to the gravitational Aharonov-Bohm effect. We further demonstrate that our gravitational framework can be applied to the topological phase transition driven by the vortex-linking precess in three-dimensional helical superconductors such as the He-B phase.
format Preprint
id arxiv_https___arxiv_org_abs_2507_06586
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Time-reversal invariant vortex in topological superconductors and gravitational $\mathbb{Z}_2$ topology
Yamamoto, Kazuki
Kan, Naoto
Fukaya, Hidenori
Mesoscale and Nanoscale Physics
Quantum Gases
Superconductivity
High Energy Physics - Lattice
High Energy Physics - Theory
We study a time-reversal invariant vortex, namely a spin vortex, in helical superconductors by focusing on its emergent gravitational structure. The topology of the time-reversal invariant vortex is classified by a $\mathbb{Z}_2$ invariant: helical Majorana zero modes appear at the vortex core when the winding number is odd, while no such zero modes exist when it is even. We provide a formal mapping to the theory of gravity to describe this $\mathbb{Z}_2$ topological structure. Identifying a superconducting order parameter as a vielbein in the theory of gravity, we explicitly convert the Bogoliubov-de-Genne Hamiltonian into the Dirac Hamiltonian coupled to a nontrivial gravitational field. Then we find that a gravitational curvature is induced at the vortex core, with its total flux quantized in integer multiples of $π$, reflecting the $\mathbb{Z}_2$ topology. Although the curvature vanishes everywhere except at the vortex core, the energy spectrum remains sensitive to the total curvature flux, owing to the gravitational Aharonov-Bohm effect. We further demonstrate that our gravitational framework can be applied to the topological phase transition driven by the vortex-linking precess in three-dimensional helical superconductors such as the He-B phase.
title Time-reversal invariant vortex in topological superconductors and gravitational $\mathbb{Z}_2$ topology
topic Mesoscale and Nanoscale Physics
Quantum Gases
Superconductivity
High Energy Physics - Lattice
High Energy Physics - Theory
url https://arxiv.org/abs/2507.06586