Lipschitz stability for the Finite Dimensional Fractional Calder\'on Problem with Finite Cauchy Data

In this note we discuss the conditional stability issue for the finite dimensional Calder'on problem for the fractional Schr"{o}dinger equation with a finite number of measurements. More precisely, we assume that the unknown potential $q\in L^{\mathrm{\infty }}(\mathrm{\Omega })$ in the equation $((-\Delta)^s+ q)u = 0 \mbox{ in } \Omega\subset $\mathbb{R}$^n$ satisfies the a priori assumption that it is contained in a finite dimensional subspace of $L^{\mathrm{\infty }}(\mathrm{\Omega })$. Under this condition we prove Lipschitz stability estimates for the fractional Calder'on problem by means of finitely many Cauchy data depending on $q$. We allow for the possibility of zero being a Dirichlet eigenvalue of the associated fractional Schr"odinger equation. Our result relies on the strong Runge approximation property of the fractional Schr"odinger equation.