# Covariant and quasi-covariant quantum dynamics in Robertson-Walker space-times

Detlev Buchholz, Jens Mund, Stephen J. Summers
July 06, 2002
We propose a canonical description of the dynamics of quantum systems on a class of Robertson-Walker space-times. We show that the worldline of an observer in such space-times determines a unique orbit in the local conformal group SO(4,1) of the space-time and that this orbit determines a unique transport on the space-time. For a quantum system on the space time modeled by a net of local algebras, the associated dynamics is expressed via a suitable family of propagators''. In the best of situations, this dynamics is covariant, but more typically the dynamics will be quasi-covariant'' in a sense we make precise. We then show by using our technique of transplanting'' states and nets of local algebras from de Sitter space to Robertson-Walker space that there exist quantum systems on Robertson-Walker spaces with quasi-covariant dynamics. The transplanted state is locally passive, in an appropriate sense, with respect to this dynamics.