Photon wave functions in a localized coordinate space basis

A first quantized theory of the photon is developed that incorporates all o f the usual rules of quantum mechanics. The state vector is argued to be pr oportional to the four-vector potential, Scalar products and the probabilit y amplitude an invariant under gauge transformations that satisfy the Loren tz gauge condition. The eigenvectors of a recently constructed Hermitian po sition operator with commuting components provide a basis for the position representation. [S1050-2947(99)02605-0].