Spectral estimate for the Laplace-Beltrami operator on the hyperbolic half-plane

The purpose of this note is to investigate the concentration properties of spectral projectors on manifolds. This question has been intensively studied (by Logvinenko–Sereda, Nazarov, Jerison–Lebeau, Kovrizhkin, Egidi–Seelmann–Veseli{ć}, Burq–Moyano, among others) in connection with the uncertainty principle. We provide the first high-frequency results in a geometric setting which is neither Euclidean nor a perturbation of Euclidean. Namely, we prove the natural (and optimal) uncertainty principle for the spectral projector on the hyperbolic half-plane.