$2+1$ dimensional Floquet systems and lattice fermions: Exact bulk spectral equivalence

A connection has recently been proposed between periodically driven systems known as Floquet insulators in continuous time and static fermion theories in discrete time. This connection has been established in a $(1+1)$-dimensional free theory, where an explicit mapping between the spectra of a Floqu...

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Main Author: Thomas Iadecola, Srimoyee Sen, Lars Sivertsen
Format: Article
Language:English
Published: SciPost 2025-04-01
Series:SciPost Physics Core
Online Access:https://scipost.org/SciPostPhysCore.8.2.035
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author Thomas Iadecola, Srimoyee Sen, Lars Sivertsen
author_facet Thomas Iadecola, Srimoyee Sen, Lars Sivertsen
author_sort Thomas Iadecola, Srimoyee Sen, Lars Sivertsen
collection DOAJ
description A connection has recently been proposed between periodically driven systems known as Floquet insulators in continuous time and static fermion theories in discrete time. This connection has been established in a $(1+1)$-dimensional free theory, where an explicit mapping between the spectra of a Floquet insulator and a discrete-time Dirac fermion theory has been formulated. Here we investigate the potential of static discrete-time theories to capture Floquet physics in higher dimensions, where so-called anomalous Floquet topological insulators can emerge that feature chiral edge states despite having bulk bands with zero Chern number. Starting from a particular model of an anomalous Floquet system, we provide an example of a static discrete-time theory whose bulk spectrum is an exact analytic match for the Floquet spectrum. The spectra with open boundary conditions in a particular strip geometry also match up to finite-size corrections. However, the models differ in several important respects. The discrete-time theory is spatially anisotropic, so that the spectra do not agree for all lattice terminations, e.g. other strip geometries or on half spaces. This difference can be attributed to the fact that the static discrete-time model is quasi-one-dimensional in nature and therefore has a different bulk-boundary correspondence than the Floquet model.
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spelling doaj-art-cd646b2a1ded47ce94fa6749361952ec2025-08-20T01:55:57ZengSciPostSciPost Physics Core2666-93662025-04-018203510.21468/SciPostPhysCore.8.2.035$2+1$ dimensional Floquet systems and lattice fermions: Exact bulk spectral equivalenceThomas Iadecola, Srimoyee Sen, Lars SivertsenA connection has recently been proposed between periodically driven systems known as Floquet insulators in continuous time and static fermion theories in discrete time. This connection has been established in a $(1+1)$-dimensional free theory, where an explicit mapping between the spectra of a Floquet insulator and a discrete-time Dirac fermion theory has been formulated. Here we investigate the potential of static discrete-time theories to capture Floquet physics in higher dimensions, where so-called anomalous Floquet topological insulators can emerge that feature chiral edge states despite having bulk bands with zero Chern number. Starting from a particular model of an anomalous Floquet system, we provide an example of a static discrete-time theory whose bulk spectrum is an exact analytic match for the Floquet spectrum. The spectra with open boundary conditions in a particular strip geometry also match up to finite-size corrections. However, the models differ in several important respects. The discrete-time theory is spatially anisotropic, so that the spectra do not agree for all lattice terminations, e.g. other strip geometries or on half spaces. This difference can be attributed to the fact that the static discrete-time model is quasi-one-dimensional in nature and therefore has a different bulk-boundary correspondence than the Floquet model.https://scipost.org/SciPostPhysCore.8.2.035
spellingShingle Thomas Iadecola, Srimoyee Sen, Lars Sivertsen
$2+1$ dimensional Floquet systems and lattice fermions: Exact bulk spectral equivalence
SciPost Physics Core
title $2+1$ dimensional Floquet systems and lattice fermions: Exact bulk spectral equivalence
title_full $2+1$ dimensional Floquet systems and lattice fermions: Exact bulk spectral equivalence
title_fullStr $2+1$ dimensional Floquet systems and lattice fermions: Exact bulk spectral equivalence
title_full_unstemmed $2+1$ dimensional Floquet systems and lattice fermions: Exact bulk spectral equivalence
title_short $2+1$ dimensional Floquet systems and lattice fermions: Exact bulk spectral equivalence
title_sort 2 1 dimensional floquet systems and lattice fermions exact bulk spectral equivalence
url https://scipost.org/SciPostPhysCore.8.2.035
work_keys_str_mv AT thomasiadecolasrimoyeesenlarssivertsen 21dimensionalfloquetsystemsandlatticefermionsexactbulkspectralequivalence