An uncertainty principle on compact manifolds

Abstract

Breitenberger's uncertainty principle on the torus $\mathbb{T}$ and its higher-dimensional analogue on ${\mathbb{S}}^{d-1}$ are well understood. We give describe an entire family of uncertainty principles on compact manifolds $(M,g)$, which includes the classical Heisenberg-Weyl uncertainty principle (for $M=B(0,1)\subset {\mathbb{R}}^d$ the unit ball with the flat metric) and the Goh-Goodman uncertainty principle (for $M={\mathbb{S}}^{d-1}$ with the canonical metric) as special cases. This raises a new geometric problem related to small-curvature low-distortion embeddings: given a function $f:M\to \mathbb{R}$, which uncertainty principle in our family yields the best result? We give a (far from optimal) answer for the torus, discuss disconnected manifolds and state a variety of other open problems.

17 pages, 8 figures, to appear in The Journal of Fourier Analysis and Applications