Non-Asymptotic behaviour of the spectrum of the Sinc Kernel Operator and Related Applications

TL;DR

This paper provides precise non-asymptotic estimates for the eigenvalues of the Sinc-kernel operator, with applications in harmonic analysis, signal processing, and random matrix theory, filling a gap in the understanding of its spectrum.

Contribution

It offers the first detailed non-asymptotic bounds for the spectrum of the Sinc-kernel operator across all regions, extending the asymptotic analysis.

Findings

Derived non-asymptotic eigenvalue estimates in all spectral regions.

Applied estimates to concentration inequalities like Remez and Turań-Nazarov.

Provided bounds for hole probabilities in GUE random matrices.

Abstract

Prolate spheroidal wave functions have recently attracted a lot of attention in applied harmonic analysis, signal processing and mathematical physics. They are eigenvectors of the Sinc-kernel operator Qc : the time-and band-limiting operator. The corresponding eigenvalues play a key role and it is the aim of this paper to obtain precise non-asymptotic estimates for these eigenvalues, within the three main regions of the spectrum of Qc. This issue is rarely studied in the literature, while the asymptotic behaviour of the spectrum of Qc has been well established from the sixties. As applications of our non-asymptotic estimates, we first provide estimates for the constants appearing in Remez and Tur{\`a}n-Nazarov type concentration inequalities. Then, we give an estimate for the hole probability, associated with a random matrix from the Gaussian Unitary Ensemble (GUE).