  In this article, we study the boundary inverse problem of determining the
aligned magnetic fiaeld appearing in the magnetic Schr\"odinger equation in a
periodic quantum cylindrical waveguide. Provided that the Dirichlet-to-Neumann
map of the magnetic Schr\"odinger equation. We prove a Holder stability
estimate with respect to the Dirichlet-to-Neumann map, by means of the
geometrical optics solutions of the magnetic Schrodinger equation.
