arXiv subjects

Ronny Hadani

Publications and source records attributed to Ronny Hadani.

48 records · Page 3Linked to original sources

arXiv2008

On some deterministic dictionaries supporting sparsity

We describe a new construction of an incoherent dictionary, referred to as the oscillator dictionary, which is based on considerations in the representation theory of finite groups. The oscillator dictionary consists of order of p^5 unit vectors in a Hilbert space of dimension p, where p is an odd prime, whose pairwise inner products have magnitude of at most 4/sqrt(p). An explicit algorithm to construct a large portion of the oscillator dictionary is presented.

cs.IT↗

arXiv2008

On the diagonalization of the discrete Fourier transform

The discrete Fourier transform (DFT) is an important operator which acts on the Hilbert space of complex valued functions on the ring Z/NZ. In the case where N=p is an odd prime number, we exhibit a canonical basis of eigenvectors for the DFT. The transition matrix from the standard basis to the canonical basis defines a novel transform which we call the discrete oscillator transform (DOT for short). Finally, we describe a fast algorithm for computing the discrete oscillator transform in certain cases.

cs.IT↗

arXiv2008

The statistical restricted isometry property and the Wigner semicircle distribution of incoherent dictionaries

In this article we present a statistical version of the Candes-Tao restricted isometry property (SRIP for short) which holds in general for any incoherent dictionary which is a disjoint union of orthonormal bases. In addition, we show that, under appropriate normalization, the eigenvalues of the associated Gram matrix fluctuate around 1 according to the Wigner semicircle distribution. The result is then applied to various dictionaries that arise naturally in the setting of finite harmonic analysis, giving, in particular, a better understanding on a remark of Applebaum-Howard-Searle-Calderbank concerning RIP for the Heisenberg dictionary of chirp like functions.

cs.IT↗

arXiv2008

The discrete Fourier transform: A canonical basis of eigenfunctions

The discrete Fourier transform (DFT) is an important operator which acts on the Hilbert space of complex valued functions on the ring Z/NZ. In the case where N=p is an odd prime number, we exhibit a canonical basis of eigenvectors for the DFT. The transition matrix from the standard basis to the canonical basis defines a novel transform which we call the "discrete oscillator transform" (DOT for short). Finally, we describe a fast algorithm for computing the DOT in certain cases.

cs.IT↗

arXiv2008

The Weil Representation in Characteristic Two

In this paper we construct a new variant of the Weil representation, associated with a symplectic vector space V defined over a finite field of characteristic two. Our variant is a representation of a bigger group than that of Weil. In the course, we develop the formalism of canonical vector spaces, which enables us to realize the bigger symmetry group and the representation in a transparent manner.

math.RT↗

arXiv2007

The Geometric Weil Representation

In this paper we construct a geometric analogue of the Weil representation over a finite field. Our construction is principally invariant, not choosing any specific realization. This eliminates most of the unpleasant formulas that appear in the traditional (non-invariant) approaches, and puts in the forefront some delicate geometric phenomena which underlie this representation.

math.RT↗

arXiv2006

Proof of the Kurlberg-Rudnick Rate Conjecture

In this paper we present a proof of the {\it Hecke quantum unique ergodicity rate conjecture} for the Berry-Hannay model. A model of quantum mechanics on the 2-dimensional torus. This conjecture was stated in Z. Rudnick's lectures at MSRI, Berkeley 1999 and ECM, Barcelona 2000.

math-ph↗

arXiv2005

Heisenberg Realizations, Eigenfunctions and Proof of the Kurlberg-Rudnick Supremum Conjecture

In this paper, proof of the {\it Kurlberg-Rudnick supremum conjecture} for the quantum Hannay-Berry model is presented. This conjecture was stated in P. Kurlberg's lectures at Bologna 2001 and Tel-Aviv 2003. The proof is a primer application of a fundamental solution: all the Hecke eigenfunctions of the quantum system are constructed. The main tool in our construction is the categorification of the compatible system of realizations of the Heisenberg representation over a finite field. This enables us to construct certain "perverse sheaves" that stands motivically prior to the Hecke eigenfunctions.

math-ph↗

arXiv2005

Proof of the Kurlberg-Rudnick Rate Conjecture

In this paper we present a proof of the {\it Hecke quantum unique ergodicity conjecture} for the Berry-Hannay model, a model of quantum mechanics on a two dimensional torus. This conjecture was stated in Z. Rudnick's lectures at MSRI, Berkeley, 1999 and ECM, Barcelona, 2000.

math-ph↗

arXiv2005

The Two Dimensional Hannay-Berry Model

The main goal of this paper is to construct the Hannay-Berry model of quantum mechanics, on a two dimensional symplectic torus. We construct a simultaneous quantization of the algebra of functions and the linear symplectic group $\G =$ SL$_2 (\Z)$. We obtain the quantization via an action of $\G$ on the set of equivalence classes of irreducible representations of Rieffel`s quantum torus $\Ad$. For $\h \in \Q$ this action has a unique fixed point. This gives a canonical projective equivariant quantization. There exists a Hilbert space on which both $\G$ and $\Ad$ act equivariantly. Combined with the fact that every projective representation of $\G$ can be lifted to a linear representation, we also obtain linear equivariant quantization.

math-ph↗

arXiv2004

The Higher-Dimensional Rudnick-Kurlberg Conjecture

In this paper we give a proof of the {\it Hecke quantum unique ergodicity conjecture} for the multidimensional Berry-Hannay model. A model of quantum mechanics on the 2n-dimensional torus. This result generalizes the proof of the {\it Rudnick-Kurlberg Conjecture} given in \cite{GH3} for the 2-dimensional torus.

math-ph↗

arXiv2004

The Multidimensional Berry-Hannay Model

The aim of this paper is to construct the Berry-Hannay model of quantum mechanics on a 2n-dimensional symplectic torus. We construct a simultaneous quantization of the algebra $\cal A$ of functions on the torus and the linear symplectic group $\G = \Sp(\mathrm{2n},\Z)$. In the construction we use the quantum torus $\A$, which is a deformation of $\cal A$, together with a $\G$-action on it. We obtain the quantization via the action of $\G$ on the set of equivalence classes of irreducible representations of $\A$. For $\h \in \Q$ this action has a unique fixed point. This gives a canonical projective equivariant quantization. There exists a Hilbert space on which both $\G$ and $\A$ act in a compatible way.

math-ph↗