  This paper presents a novel path integral formalism for Einstein's theory of
gravitation from the viewpoint of optimal control theory. Despite its close
relation to the well-known variational principles of physicists, optimal
control turns out to be more general. Within this context, a Lagrangian
different from the Einstein-Hilbert Lagrangian is defined. Einstein field
equations are recovered exactly with variations of the new action functional.
The quantum theory is obtained using Ashtekar variables and the loop scalar
product. By means of example, the tunneling process of a black hole into
another black hole or into a white hole is investigated with a toy model.
