Trace and Observability Inequalities for Laplace Eigenfunctions on the Torus

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Main Authors: Burq, Nicolas, Germain, Pierre, Sorella, Massimo, Zhu, Hui
Format: Preprint
Published: 2025
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_version_ 1866912496823042048
author Burq, Nicolas
Germain, Pierre
Sorella, Massimo
Zhu, Hui
author_facet Burq, Nicolas
Germain, Pierre
Sorella, Massimo
Zhu, Hui
contents We investigate trace and observability inequalities for Laplace eigenfunctions on the d-dimensional torus, with respect to arbitrary Borel measures $μ$. Specifically, we characterize the measures $μ$ for which the inequalities $$ \int |u|^2 d μ\lesssim \int |u|^2 d x \quad \text{(trace)}, \qquad \int |u|^2 d μ\gtrsim \int |u|^2 d x \quad \text{(observability)}$$ hold uniformly for all eigenfunctions $u$ of the Laplacian. Sufficient conditions are derived based on the integrability and regularity of $μ$, while necessary conditions are formulated in terms of the dimension of the support of the measure. These results generalize classical theorems of Zygmund and Bourgain--Rudnick to higher dimensions. Applications include results in the spirit of Cantor--Lebesgue theorems, constraints on quantum limits, and control theory for the Schrödinger equation. Our approach combines several tools: the cluster structure of lattice points on spheres; decoupling estimates; and the construction of eigenfunctions exhibiting strong concentration or vanishing behavior, tailored respectively to the trace and observability inequalities.
format Preprint
id arxiv_https___arxiv_org_abs_2507_16599
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Trace and Observability Inequalities for Laplace Eigenfunctions on the Torus
Burq, Nicolas
Germain, Pierre
Sorella, Massimo
Zhu, Hui
Analysis of PDEs
Mathematical Physics
Classical Analysis and ODEs
Number Theory
Spectral Theory
58J50, 35P20, 11P21
We investigate trace and observability inequalities for Laplace eigenfunctions on the d-dimensional torus, with respect to arbitrary Borel measures $μ$. Specifically, we characterize the measures $μ$ for which the inequalities $$ \int |u|^2 d μ\lesssim \int |u|^2 d x \quad \text{(trace)}, \qquad \int |u|^2 d μ\gtrsim \int |u|^2 d x \quad \text{(observability)}$$ hold uniformly for all eigenfunctions $u$ of the Laplacian. Sufficient conditions are derived based on the integrability and regularity of $μ$, while necessary conditions are formulated in terms of the dimension of the support of the measure. These results generalize classical theorems of Zygmund and Bourgain--Rudnick to higher dimensions. Applications include results in the spirit of Cantor--Lebesgue theorems, constraints on quantum limits, and control theory for the Schrödinger equation. Our approach combines several tools: the cluster structure of lattice points on spheres; decoupling estimates; and the construction of eigenfunctions exhibiting strong concentration or vanishing behavior, tailored respectively to the trace and observability inequalities.
title Trace and Observability Inequalities for Laplace Eigenfunctions on the Torus
topic Analysis of PDEs
Mathematical Physics
Classical Analysis and ODEs
Number Theory
Spectral Theory
58J50, 35P20, 11P21
url https://arxiv.org/abs/2507.16599