Uniqueness in the Calder\'on problem via infinitesimally bounded potentials

The Calder'on problem is an inverse problem with applications to electrical impedance tomography and geophysical prospection. We prove uniqueness in the Calder'on problem in spatial dimension $n\ge 3$ for scalar conductivities in the Sobolev space $W^{1,p}$ with $p\ge n$. This generalizes a result of Haberman who considered the case $p\ge n$ and $n=3$ or $4$. Our method of proof combines a Fourier series approach with an analytic criterion for infinitesimal boundedness of potentials appearing in a Schr"odinger equation with respect to the Laplacian.