  In a separable Hilbert space $X$, we study the linear evolution equation
\begin{equation*} u'(t)+Au(t)+p(t)Bu(t)=0, \end{equation*} where $A$ is an
accretive self-adjoint linear operator, $B$ is a bounded linear operator on
$X$, and $p\in L^2_{loc}(0,+\infty)$ is a bilinear control.
  We give sufficient conditions in order for the above control system to be
locally controllable to the ground state solution, that is, the solution of the
free equation ($p\equiv0$) starting from the ground state of $A$. We also
derive global controllability results in large time and discuss applications to
parabolic equations in low space dimension.
