Quantitative unique continuation and observability on an equidistributed set for the diffusion equation in R^N

TL;DR

This paper establishes quantitative unique continuation and observability inequalities for the diffusion equation in R^N, showing that total solution energy can be controlled by localized energy in an equidistributed set.

Contribution

It provides new quantitative estimates and observability results for the diffusion equation in unbounded space, using reduction methods and propagation of smallness techniques.

Findings

Energy of solutions can be estimated from localized measurements.

Quantitative unique continuation holds for solutions in R^N.

Observability inequalities are established for equidistributed sets.

Abstract

In this paper, we obtain a quantitative estimate of unique continuation and an observability inequality from an equidistributed set for solutions of the diffusion equation in the whole space RN. This kind of observability indicates that the total energy of solutions can be controlled by the energy localized in a measurable subset, which is equidistributed over the whole space. The proof of our results is based on an interesting reduction method [18, 22], as well as the propagation of smallness for the gradient of solutions to elliptic equations [24].