  The Kodama state is unique in being an exact solution to all the constraints
of quantum gravity that also has a well defined semi-classical interpretation
as the quantum version of a classical spacetime, namely de Sitter or anti-de
sitter space. Despite this, the state fails to pass some of the key tests of a
physically realistic quantum state. In an attempt to resolve this problem, we
track down the root of the problem to a choice for a particular parameter: the
Immirzi parameter. The Kodama state takes this parameter to be complex, whereas
modern formulations of canonical quantum gravity require that the parameter is
real. We generalize the Kodama state to real values of the Immirzi parameter,
and find that the generalization opens up a large Hilbert space of states, one
of which can be directly interpreted as particular slicing of de Sitter space.
We then show that these states resolve, or are expected to resolve many of the
problems associated with the original version of the Kodama state. In order to
resolve the interpretation of the multitude of states, we develop a new model
of covariant classical and quantum gravity where the full Lorentz group is
retained as a local symmetry group, and the canonical evolution generated by
the constraints has a close relation to a larger group: the de Sitter group.
This formalism gives strong evidence that the multitude of generalized Kodama
states can be unified into a single quantum state that is quantum de Sitter
space.
