Solidification of porous interfaces and disconnection

Abstract

In this article we obtain uniform estimates on the absorption of Brownian motion by porous interfaces surrounding a compact set. An important ingredient is the construction of certain resonance sets, which are hard to avoid for Brownian motion starting in the compact set. As an application of our results, we substantially strengthen the results of [22], and obtain when $d\ge 3$, large deviation upper bounds on the probability that simple random walk in ${\mathbb{Z}}^d$, or random interlacements in ${\mathbb{Z}}^d$, when their vacant set is in a strongly percolative regime, disconnect the discrete blow-up of a regular compact set from the boundary of the discrete blow-up of a box containing the compact set in its interior. Importantly, we make no convexity assumption on the compact set. It is plausible, although open at the moment, that the upper bounds that we derive in this work match in principal order the lower bounds of [15] in the case of random interlacements, and of [14] for the simple random walk.