Beurling density theorems for sampling and interpolation on the flat cylinder

Fuente: arXiv
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Main Authors: Abreu, Luis Daniel, Luef, Franz, Ziyat, Mohammed
Format: Preprint
Published: 2024
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author Abreu, Luis Daniel
Luef, Franz
Ziyat, Mohammed
author_facet Abreu, Luis Daniel
Luef, Franz
Ziyat, Mohammed
contents We consider the Fock space weighted by $e^{-α|z|^{2}}$, of entire and quasi-periodic (modulo a weight dependent on $ν$) functions on ${C}$. The quotient space $\mathbb{C}/\mathbb{Z}$, called `The flat cylinder', is represented by the vertical strip $[0,1)\times \mathbb{R}$, which tiles ${C}$ by ${Z}$-translations and is therefore a fundamental domain for $\mathbb{C}/\mathbb{Z}$. Our main result gives a complete characterization of the sets $Z\subset Λ\left( \mathbb{Z}\right) $ that are sets of sampling or interpolation, in terms of concepts of upper and lower Beurling densities, $ D^{+}(Z)$ and $D^{-}(Z)$, adapted to the geometry of $\mathbb{C}/\mathbb{Z}$. The critical `Nyquist density' is the real number $\frac{α}{π}$, meaning that the condition $D^{-}(Z)>\frac{α}{π}$ characterizes sets of sampling, while the condition $D^{+}(Z)<\frac{α}{π}$ characterizes sets of interpolation. The results can be reframed as a complete characterization of Gabor frames and Riesz basic sequences (given by arbitrary discrete sets in $Z\subset Λ\left( \mathbb{Z}\right) $), with time-periodized Gaussian windows (theta-Gaussian), for spaces of functions $f$, measurable in $\mathbb{R}$, square-integrable in $(0,1)$, and quasi-periodic with respect to integer translations.
format Preprint
id arxiv_https___arxiv_org_abs_2412_21094
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Beurling density theorems for sampling and interpolation on the flat cylinder
Abreu, Luis Daniel
Luef, Franz
Ziyat, Mohammed
Functional Analysis
Classical Analysis and ODEs
Complex Variables
We consider the Fock space weighted by $e^{-α|z|^{2}}$, of entire and quasi-periodic (modulo a weight dependent on $ν$) functions on ${C}$. The quotient space $\mathbb{C}/\mathbb{Z}$, called `The flat cylinder', is represented by the vertical strip $[0,1)\times \mathbb{R}$, which tiles ${C}$ by ${Z}$-translations and is therefore a fundamental domain for $\mathbb{C}/\mathbb{Z}$. Our main result gives a complete characterization of the sets $Z\subset Λ\left( \mathbb{Z}\right) $ that are sets of sampling or interpolation, in terms of concepts of upper and lower Beurling densities, $ D^{+}(Z)$ and $D^{-}(Z)$, adapted to the geometry of $\mathbb{C}/\mathbb{Z}$. The critical `Nyquist density' is the real number $\frac{α}{π}$, meaning that the condition $D^{-}(Z)>\frac{α}{π}$ characterizes sets of sampling, while the condition $D^{+}(Z)<\frac{α}{π}$ characterizes sets of interpolation. The results can be reframed as a complete characterization of Gabor frames and Riesz basic sequences (given by arbitrary discrete sets in $Z\subset Λ\left( \mathbb{Z}\right) $), with time-periodized Gaussian windows (theta-Gaussian), for spaces of functions $f$, measurable in $\mathbb{R}$, square-integrable in $(0,1)$, and quasi-periodic with respect to integer translations.
title Beurling density theorems for sampling and interpolation on the flat cylinder
topic Functional Analysis
Classical Analysis and ODEs
Complex Variables
url https://arxiv.org/abs/2412.21094