Green Function Invariants for Floquet Topological Superconductivity Induced by Proximity Effects

Fuente: arXiv
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Autores principales: Assili, Mohamed, Kotetes, Panagiotis
Formato: Preprint
Publicado: 2025
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author Assili, Mohamed
Kotetes, Panagiotis
author_facet Assili, Mohamed
Kotetes, Panagiotis
contents We bring forward a Green function approach for the prediction of Floquet topological phases in driven superconductor-semiconductor hybrids. Although it is common to treat the superconducting component as a mere Cooper-pair reservoir, it was recently pointed out that such an approximation breaks down in the presence of driving, due to the emergence of level broadening. Here, we go beyond these recent works and prescribe how to construct the Floquet topological invariants for such driven hybrids. Specifically, we propose to first obtain the midgap quasi-energy spectra by including the hermitian part of the semiconductor's self-energy and, subsequently, read out the respective level broadenings by projecting the anti-hermitian part of the self-energy onto the quasi-energy eigenvectors. We exemplify our approach for a Rashba nanowire coupled to a superconductor and a time-dependent Zeeman field. Using our method, we obtain the Floquet band structure, the respective level broadenings, and the topological invariants. Our analysis reinforces the need to properly account for the self-energy, and corroborates that broadening effects can hinder the observation of the Floquet topological phases and especially of those harboring Majorana $π$ modes.
format Preprint
id arxiv_https___arxiv_org_abs_2511_09650
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Green Function Invariants for Floquet Topological Superconductivity Induced by Proximity Effects
Assili, Mohamed
Kotetes, Panagiotis
Mesoscale and Nanoscale Physics
Superconductivity
Quantum Physics
We bring forward a Green function approach for the prediction of Floquet topological phases in driven superconductor-semiconductor hybrids. Although it is common to treat the superconducting component as a mere Cooper-pair reservoir, it was recently pointed out that such an approximation breaks down in the presence of driving, due to the emergence of level broadening. Here, we go beyond these recent works and prescribe how to construct the Floquet topological invariants for such driven hybrids. Specifically, we propose to first obtain the midgap quasi-energy spectra by including the hermitian part of the semiconductor's self-energy and, subsequently, read out the respective level broadenings by projecting the anti-hermitian part of the self-energy onto the quasi-energy eigenvectors. We exemplify our approach for a Rashba nanowire coupled to a superconductor and a time-dependent Zeeman field. Using our method, we obtain the Floquet band structure, the respective level broadenings, and the topological invariants. Our analysis reinforces the need to properly account for the self-energy, and corroborates that broadening effects can hinder the observation of the Floquet topological phases and especially of those harboring Majorana $π$ modes.
title Green Function Invariants for Floquet Topological Superconductivity Induced by Proximity Effects
topic Mesoscale and Nanoscale Physics
Superconductivity
Quantum Physics
url https://arxiv.org/abs/2511.09650