We extend an uncertainty principle due to Beurling into a characterization of
Hermite functions. More precisely, all functions $f$ on $\mathbb{R}^d$ which may
be written as $P(x)\exp (-\langle Ax, x\rangle)$, with $A$ a real symmetric
definite positive matrix, are characterized by integrability conditions on the
product $f(x) \widehat{f}(y)$. We then obtain similar results for the windowed
Fourier transform (also known, up to elementary changes of functions, as the
radar ambiguity function or the Wigner transform). We complete the paper with a
sharp version of Heisenberg's inequality for this transform.
@article{1049123079,
author = {Bonami, Aline and Demange, Bruno and Jaming, Philippe},
title = {Hermite functions and uncertainty principles for the
Fourier and the windowed Fourier transforms},
journal = {Rev. Mat. Iberoamericana},
volume = {19},
number = {2},
year = {2003},
pages = { 23-55},
language = {en},
url = {http://dml.mathdoc.fr/item/1049123079}
}
Bonami, Aline; Demange, Bruno; Jaming, Philippe. Hermite functions and uncertainty principles for the
Fourier and the windowed Fourier transforms. Rev. Mat. Iberoamericana, Tome 19 (2003) no. 2, pp. 23-55. http://gdmltest.u-ga.fr/item/1049123079/