The short periodic orbit approach is adapted for the quantum cat maps. The main objective is to explain, in a simple abstract model, the most relevant characteristics of this method which was originally developed for Hamiltonian fluxes. In particular, we describe a semiclassical Hamiltonian formulation to evaluate eigenphases and eigenstates of quantum cat maps. The main advantage of this formulation is that each eigenstate is described in terms of a small number, N/ln N, of short periodic orbits, with N the dimension of the Hilbert space. Moreover, matrix elements can be obtained semiclassically with high accuracy in terms of a very small number, of the order of ln²N, of homoclinic and heteroclinic orbits. From the computational point of view, this approach reduces the size of matrices used to the order N/ln N.