Approximate null-controllability of discrete heat equations with potentials on lattices
We investigate approximate null-controllability for semi-discrete heat equations on the lattice $h\mathbb{Z}^d$ with a potential. By establishing spectral inequalities for the discrete Schr{ö}dinger operator $P_h = -Δ_h + V$ on equidistributed sets, we derive observability estimates via the Lebeau-Robbiano method and the Hilbert Uniqueness Method. For bounded potentials, we obtain quantitative controllability results with explicit dependence on the potential and show near optimality of the geometric condition on the observation set. We also treat polynomial growth potentials, for which similar properties hold with weaker control cost estimates. These results extend discrete Carleman techniques to the full-space lattice setting and provide new spectral estimates for discrete Schr{ö}dinger operators.