Modular Theory and Bogoliubov Automorphisms of Clifford Algebras

Let _c be a covariance C quasifree representation of the Cliffordalgebra over a real Hilbert space on which I + C² is invertible.We determine explicitly the modular data for _c and show thata Bogoliubov automorphism is weakly inner for _c if and onlyif its generating orthogonal transformation lies in the Blattnergroup. We employ a model in which all quasifree representationsact on one canonical Hilbert space, exhibiting the propertythat the modular conjugation is independent of C. This refinesearlier work of Carey, Shale and Stinespring.