Education
Graham attended the Karls-Gymnasium in Stuttgart and studied at the University of Stuttgart, where in 1967 he earned under Hermann Haken his physics Diplom (quantum fluctuations of the optical parametric oscillator) and in 1969 his Doctor of Philosophy (light propagation in laser-active fluctuating media).
Career
Continuing this work, he applied the theory of cooperative systems publicized by Haken as "Synergetik" (Synergetics) in quantum optics. As a post-doc, he was a guest scientist at New York University and, after his Habilitation in 1971, scientific advisor and professor at the University of Stuttgart. From 1975 he was a professor at the Universität Duisburg-Essen, where he is now retired as professor emeritus.
He was there also dean and prorector for research.
He worked on extremely diverse areas of quantum theoretical statistical mechanics, apart from laser theory also in the 1990s with the theory of Bose–Einstein condensate.