Noncommutative Bourgain's circular maximal theorem and a local smoothing estimate on the generalized Moyal planes
Guixiang Hong, Xudong Lai, Liang Wang
TL;DR
This work establishes a local smoothing estimate for the wave equation on two-dimensional quantum Euclidean space $\mathcal{R}_\theta^2$ and resolves the noncommutative analogue of Bourgain's circular maximal theorem. The authors develop a noncommutative transference technique to reduce to operator-valued Fourier multipliers, and prove scale-local $L_p$ bounds via Littlewood-Paley theory, operator-valued Sobolev embeddings, and Kakeya-type maximal inequalities. Central contributions include the first noncommutative 2D local smoothing result and a complete resolution of the noncommutative circular maximal inequality, underpinned by new geometric and analytic tools in the noncommutative setting. The approach combines transference, operator-valued harmonic analysis, and refined geometric estimates in $\mathbb{R}^3$, with potential implications for further noncommutative PDEs on quantum manifolds and related microlocal analysis.
Abstract
In this paper, we establish a local smoothing estimate on two-dimensional quantum Euclidean space. This is the noncommutative analogue of the one due to Mockenhaupt$-$Seeger$-$Sogge \cite{MSS}. As an application and simultaneously one motivation, we obtain the noncommutative analogue of Bourgain's circular maximal theorem, resolving one problem after \cite{Hong}.
