Gabor frames for quasi-periodic functions and polyanalytic spaces on the flat cylinder

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Hauptverfasser: Abreu, L. D., Luef, F., Ziyat, M.
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Veröffentlicht: 2024
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author Abreu, L. D.
Luef, F.
Ziyat, M.
author_facet Abreu, L. D.
Luef, F.
Ziyat, M.
contents We develop an alternative approach to the study of Fourier series, based on the Short-Time-Fourier Transform (STFT) acting on $L_{ν}^{2}(0,1)$, the space of measurable functions $f$ in ${R}$, square-integrable in $ (0,1)$, and time-periodic up to a phase factor: for fixed $ν\in \mathbb{R}$, \begin{equation*} f(t+k)=e^{2πikν}f(t)\text{, }k\in \mathbb{Z}\text{.} \end{equation*} The resulting phase space is $[0,1)\times {R}$, a flat model of an infinite cylinder, leading to Gabor frames with a rich structure, including a Janssen-type representation. A Gaussian window leads to a Fock space of entire functions, studied in the companion paper by the same authors [\emph{Beurling-type density theorems for sampling and interpolation on the flat cylinder}]. When $g$ is a Hermite function, we are lead to true Fock spaces of polyanalytic functions (Landau Level eigenspaces) on the vertical strip $[0,1)\times{R}$. Furthermore, an analogue of the sufficient Wexler-Raz conditions is obtained. This leads to a new criteria for Gabor frames in $L^{2}({R})$, to sufficient conditions for Gabor frames in $L_{ν}^{2}(0,1)$ with Hermite windows (an analogue of a theorem of Gröchenig and Lyubarskii about Gabor frames with Hermite windows) and with totally positive windows. We also consider a vectorial STFT in $L_{ν}^{2}(0,1)$ and the (full) Fock spaces of polyanalytic functions on $[0,1)\times {R}$, associated Bargmann-type transforms, and an analogue of Vasilevski's orthogonal decomposition into true polyanalytic Fock spaces (Landau level eigenspaces on $[0,1)\times {R}$). We conclude with an analogue of Gröchenig-Lyubarskii's sufficient condition for Gabor super-frames with Hermite functions, equivalent to a sufficient sampling condition on the full Fock space of polyanalytic functions on $[0,1)\times \mathbb{R}$.
format Preprint
id arxiv_https___arxiv_org_abs_2412_20567
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Gabor frames for quasi-periodic functions and polyanalytic spaces on the flat cylinder
Abreu, L. D.
Luef, F.
Ziyat, M.
Functional Analysis
Classical Analysis and ODEs
Complex Variables
We develop an alternative approach to the study of Fourier series, based on the Short-Time-Fourier Transform (STFT) acting on $L_{ν}^{2}(0,1)$, the space of measurable functions $f$ in ${R}$, square-integrable in $ (0,1)$, and time-periodic up to a phase factor: for fixed $ν\in \mathbb{R}$, \begin{equation*} f(t+k)=e^{2πikν}f(t)\text{, }k\in \mathbb{Z}\text{.} \end{equation*} The resulting phase space is $[0,1)\times {R}$, a flat model of an infinite cylinder, leading to Gabor frames with a rich structure, including a Janssen-type representation. A Gaussian window leads to a Fock space of entire functions, studied in the companion paper by the same authors [\emph{Beurling-type density theorems for sampling and interpolation on the flat cylinder}]. When $g$ is a Hermite function, we are lead to true Fock spaces of polyanalytic functions (Landau Level eigenspaces) on the vertical strip $[0,1)\times{R}$. Furthermore, an analogue of the sufficient Wexler-Raz conditions is obtained. This leads to a new criteria for Gabor frames in $L^{2}({R})$, to sufficient conditions for Gabor frames in $L_{ν}^{2}(0,1)$ with Hermite windows (an analogue of a theorem of Gröchenig and Lyubarskii about Gabor frames with Hermite windows) and with totally positive windows. We also consider a vectorial STFT in $L_{ν}^{2}(0,1)$ and the (full) Fock spaces of polyanalytic functions on $[0,1)\times {R}$, associated Bargmann-type transforms, and an analogue of Vasilevski's orthogonal decomposition into true polyanalytic Fock spaces (Landau level eigenspaces on $[0,1)\times {R}$). We conclude with an analogue of Gröchenig-Lyubarskii's sufficient condition for Gabor super-frames with Hermite functions, equivalent to a sufficient sampling condition on the full Fock space of polyanalytic functions on $[0,1)\times \mathbb{R}$.
title Gabor frames for quasi-periodic functions and polyanalytic spaces on the flat cylinder
topic Functional Analysis
Classical Analysis and ODEs
Complex Variables
url https://arxiv.org/abs/2412.20567