Spectrality and non-spectrality of a class of Moran measures with three-element digits

TL;DR

This paper investigates when certain Moran measures with three-element digits are spectral or non-spectral, providing new sufficient conditions and extending previous theorems in the field of spectral measures.

Contribution

It introduces new criteria for spectrality and non-spectrality of Moran measures with three-element digits, expanding the understanding of their spectral properties.

Findings

Provided sufficient conditions for spectrality of Moran measures.

Identified conditions under which Moran measures are non-spectral.

Extended previous theorems on spectral measures with new classes of Moran measures.

Abstract

A Borel probability measure \( \mu \) with compact support on \( \mathbb{R}^n \) is called spectral measure if there exists a discrete set \( \Lambda \subset \mathbb{R}^n \) such that \( E_\Lambda := \{e^{2\pi i \langle \lambda, x \rangle}: \lambda \in \Lambda\} \) forms an orthonormal basis of \( L^2(\mu) \). In this paper, we study the spectrality and non-spectrality of a class of Moran measures with three-element digits on \( \mathbb{R} \). Let $p_n\in 3\mathbb Z\setminus\{0\}$ and $\mathcal{D}_n=\{0,a_n,b_n\}$ with $\{a_n,b_n\}=\{-1,1\}\pmod 3$. It is know that the infinite convolution of uniformly discrete probability measures $$\mu_{\{p_n\},\{\mathcal D_n\}}:=\delta_{p_1^{-1}\{0,a_1,b_1\}}\ast\delta_{(p_1p_2)^{-1}\{0,a_2,b_2\}}\ast\cdots $$ is a Moran measure with compact support if and only if \begin{align*} \sum_{n=1}^{\infty}|p_{1}p_{2}\cdots p_n|^{-1}d_n<\infty,\quad \mbox{where}\;d_n=\max\{0,|a_n|, |b_n|\}. \end{align*} Without the condition $\sup_{n\geq 1}\{\frac{|a_n|+|b_n|}{|p_n|}\}<\infty$, we give two sufficient conditions under which that $\mu_{\{p_n\},\{\mathcal D_n\}}$ is a spectral measure. If $p_n=p>2$ and $\mathcal{D}_n=\{0,a_n,b_n\}$ with $\gcd(a_n,b_n)=1$, we also find an useful condition to guarantee that $\mu_{p,\{\mathcal D_n\}}$ is not a spectral measure. Our results extend some known theorems in An et al. [JFA, 2019] and Lu et al. [JFAA, 2022].