EXACT CONTROLLABILITY IN PROJECTIONS OF THE BILINEAR SCHRÖDINGER EQUATION.

We consider the bilinear Schrödinger equation with discrete-spectrum drift. We show, for n ∈ N arbitrary, exact controllability in projections on the first n given eigenstates. The controllability result relies on a generic controllability hypothesis on some associated finite-dimensional approximations. The method is based on Lie-algebraic control techniques applied to the finite-dimensional approximations coupled with classical topological arguments issuing from degree theory. [ABSTRACT FROM AUTHOR]