Uncertainty principles for integral operators

The aim of this paper is to prove new uncertainty principles for an integral operator $\tt$ with a bounded kernel for which there is a Plancherel theorem. The first of these results is an extension of Faris's local uncertainty principle which states that if a nonzero function $f\in L^2(\R^d,\mu)$ is highly localized near a single point then $\tt (f)$ cannot be concentrated in a set of finite measure. The second result extends the Benedicks-Amrein-Berthier uncertainty principle and states that a nonzero function $f\in L^2(\R^d,\mu)$ and its integral transform $\tt (f)$ cannot both have support of finite measure. From these two results we deduce a global uncertainty principle of Heisenberg type for the transformation $\tt$. We apply our results to obtain a new uncertainty principles for the Dunkl and Clifford Fourier transforms

Equality cases for the uncertainty principle in finite Abelian groups

We consider the families of finite Abelian groups \ZZ/p\ZZ\times \ZZ/p\ZZ, \ZZ/p^2\ZZ and \ZZ/p\ZZ\times \ZZ/q\ZZ for $p,q$ two distinct prime numbers. For the two first families we give a simple characterization of all functions whose support has cardinality $k$ while the size of the spectrum satisfies a minimality condition. We do it for a large number of values of $k$ in the third case. Such equality cases were previously known when $k$ divides the cardinality of the group, or for groups \ZZ/p\ZZ.Comment: Mistakes have been corrected. This paper has been accepted for publication in Acta Sci. Math. (Szeged

Strong annihilating pairs for the Fourier-Bessel transform

The aim of this paper is to prove two new uncertainty principles for the Fourier-Bessel transform (or Hankel transform). The first of these results is an extension of a result of Amrein-Berthier-Benedicks, it states that a non zero function $f$ and its Fourier-Bessel transform $\mathcal{F}_\alpha (f)$ cannot both have support of finite measure. The second result states that the supports of $f$ and $\mathcal{F}_\alpha (f)$ cannot both be (\eps,\alpha)-thin, this extending a result of Shubin-Vakilian-Wolff. As a side result we prove that the dilation of a \cc_0-function are linearly independent. We also extend Faris's local uncertainty principle to the Fourier-Bessel transform.Comment: 19p

Annihilating pairs in harmonic analysis

Cette thèse porte sur l'étude de certains aspects du principe d'incertitude en analyse harmonique.Historiquement le principe d'incertitude fut énoncé en 1927 par Heisenberg qui a montré unepropriété fondamentale de la mécanique quantique qui dit qu'il est impossible de mesurer, avecprécision, à la fois la position et la vitesse d'une particule. Le but de cette thèse est d'étendre certainsrésultats concernant les paires annihilantes à deux contextes.Dans la première partie nous étendons le principe d’incertitude local et les principes d'incertitudede Benedicks-Amrein-Berthier, de Shubin-Vakilian-Wolff et de Logvinenko-Sereda pour latransformée de Fourier-Bessel. Ces principes font qu’on ne peut pas localiser aussi précisémentqu’on le veut une fonction et sa transformée de Fourier-Bessel.Dans la deuxième partie, nous abordons les principes d'incertitude dans le cadre discret fini, dontl'intérêt a été renouvelé par la théorie de "l'échantillonnage comprimée" qui est plus connue sous levocable anglo-saxon du "compresseve sensing". Le thème général de ce travail est l'étude desprincipes d'incertitude qualitatifs et quantitatifs pour la transformée de Fourier discrète/ discrète à fenêtre.In this thesis we are interested in Uncertainty Principles. Published by Heisenberg in 1927, the uncertainty principle was a key discovery in the early development of quantum theory. It implies that it is impossible to simultaneously measure the present position and momentum of a particle. The aim of this thesis is to extend some results about annihilating pairs in two contexts. In the first part we extend the local uncertainty principle, the Benedicks-Amrein-Berthier uncertainty principle, the Shubin-Vakilian-Wolff uncertainty principle and the Logvinenko-Sereda uncertainty principle for the Fourier-Bessel transform. This uncertainty principles state that a function and its Fourier- Bessel transform cannot be simultaneously well concentrated. The aim of the second part is to deal with uncertainty principles in finite the dimensional settings witch is linked to the theory of compresseve sensing. Our result extends previously known qualitative uncertainty principles into more quantitative for the discrete Fourier transform/ short time Fourier transform

An Note on Uncertainty Inequalities for Deformed Harmonic Oscillators

The aim of this paper is to prove some uncertainty inequalities for a class of integral operators associated to deformed harmonic oscillators

Dunkl-Gabor transform and time-frequency concentration

summary:The aim of this paper is to prove two new uncertainty principles for the Dunkl-Gabor transform. The first of these results is a new version of Heisenberg's uncertainty inequality which states that the Dunkl-Gabor transform of a nonzero function with respect to a nonzero radial window function cannot be time and frequency concentrated around zero. The second result is an analogue of Benedicks' uncertainty principle which states that the Dunkl-Gabor transform of a nonzero function with respect to a particular window function cannot be time-frequency concentrated in a subset of the form $S\times \mathcal B(0,b)$ in the time-frequency plane $\mathbb R^d\times \widehat {\mathbb R}^d$. As a side result we generalize a related result of Donoho and Stark on stable recovery of a signal which has been truncated and corrupted by noise

Paires annihilantes en analyse harmonique

In this thesis we are interested in Uncertainty Principles. Published by Heisenberg in 1927, the uncertainty principle was a key discovery in the early development of quantum theory. It implies that it is impossible to simultaneously measure the present position and momentum of a particle. The aim of this thesis is to extend some results about annihilating pairs in two contexts. In the first part we extend the local uncertainty principle, the Benedicks-Amrein-Berthier uncertainty principle, the Shubin-Vakilian-Wolff uncertainty principle and the Logvinenko-Sereda uncertainty principle for the Fourier-Bessel transform. This uncertainty principles state that a function and its Fourier- Bessel transform cannot be simultaneously well concentrated. The aim of the second part is to deal with uncertainty principles in finite the dimensional settings witch is linked to the theory of compresseve sensing. Our result extends previously known qualitative uncertainty principles into more quantitative for the discrete Fourier transform/ short time Fourier transform.Cette thèse porte sur l'étude de certains aspects du principe d'incertitude en analyse harmonique.Historiquement le principe d'incertitude fut énoncé en 1927 par Heisenberg qui a montré unepropriété fondamentale de la mécanique quantique qui dit qu'il est impossible de mesurer, avecprécision, à la fois la position et la vitesse d'une particule. Le but de cette thèse est d'étendre certainsrésultats concernant les paires annihilantes à deux contextes.Dans la première partie nous étendons le principe d’incertitude local et les principes d'incertitudede Benedicks-Amrein-Berthier, de Shubin-Vakilian-Wolff et de Logvinenko-Sereda pour latransformée de Fourier-Bessel. Ces principes font qu’on ne peut pas localiser aussi précisémentqu’on le veut une fonction et sa transformée de Fourier-Bessel.Dans la deuxième partie, nous abordons les principes d'incertitude dans le cadre discret fini, dontl'intérêt a été renouvelé par la théorie de "l'échantillonnage comprimée" qui est plus connue sous levocable anglo-saxon du "compresseve sensing". Le thème général de ce travail est l'étude desprincipes d'incertitude qualitatifs et quantitatifs pour la transformée de Fourier discrète/ discrète à fenêtre

Equality cases for the uncertainty principle in finite Abelian groups

We consider the families of finite Abelian groups \ZZ/p\ZZ\times \ZZ/p\ZZ, \ZZ/p^2\ZZ and \ZZ/p\ZZ\times \ZZ/q\ZZ for $p,q$ two distinct prime numbers. For the two first families we give a simple characterization of all functions whose support has cardinality $k$ while the size of the spectrum satisfies a minimality condition. We do it for a large number of values of $k$ in the third case. Such equality cases were previously known when $k$ divides the cardinality of the group, or for groups \ZZ/p\ZZ

Logarithm Sobolev and Shannon’s Inequalities Associated with the Deformed Fourier Transform and Applications

By using the symmetry of the Dunkl Laplacian operator, we prove a sharp Shannon-type inequality and a logarithmic Sobolev inequality for the Dunkl transform. Combining these inequalities, we obtain a new, short proof for Heisenberg-type uncertainty principles in the Dunkl setting. Moreover, by combining Nash’s inequality, Carlson’s inequality and Sobolev’s embedding theorems for the Dunkl transform, we prove new uncertainty inequalities involving the L∞-norm. Finally, we obtain a logarithmic Sobolev inequality in Lp-spaces, from which we derive an Lp-Heisenberg-type uncertainty inequality and an Lp-Nash-type inequality for the Dunkl transform