Quantitative stratification for the fractional Allen-Cahn equation and stationary nonlocal minimal surface
Kelei Wang, Juncheng Wei, Ke Wu
TL;DR
The paper addresses sharp quantitative control of phase interfaces for the fractional Allen-Cahn equation with $s\in(0,\tfrac{1}{2})$ in $n\ge2$ dimensions. By adapting the quantitative stratification framework of Naber–Valtorta to the nonlocal setting via the Dirichlet-to-Neumann extension, it derives a corona-type decomposition and sharp bounds for the transition set and energy. The main contributions are optimal tubular-volume bounds on the transition region, precise convergence rates for the potential energy depending on $s$, and optimal $2s$-perimeter bounds for stationary nonlocal minimal surfaces, extending previous results without requiring strong energy assumptions. These results advance the understanding of nonlocal phase interfaces and their geometric regularity, with implications for the Gamma-convergence to nonlocal minimal surfaces and their rectifiability.
Abstract
We study properties of solutions to the fractional Allen-Cahn equation when $s\in (0, 1/2)$ and dimension $n\geq 2$. By applying the quantitative stratification principle developed by Naber and Valtorta, we obtain an optimal quantitative estimate on the transition set. As an application of this estimate, we improve the potential energy estimates of Cabre, Cinti, and Serra (2021), providing sharp versions for the fractional Allen-Cahn equation. Similarly, we obtain optimal perimeter estimates for stationary nonlocal minimal surfaces, extending previous results of Cinti, Serra, and Valdinoci (2019) from the stable case.
