He proposed the first quantum generalization of Rényi relative entropy and established its data processing inequality.
He has written or coauthored several textbooks which have been widely read by experts in quantum information theory.
From 1990-1995, he was the head of Section for Functional Analysis at the Alfréd Rényi Institute of Mathematics of the Hungarian Academy of Sciences.
From 1998-2002, he was vice dean of the Faculty of Natural Sciences of the Budapest University of Technology and Economics.
From 2004 until his death, he was research professor at the Alfréd Rényi Institute of Mathematics of the Hungarian Academy of Sciences.