He has also contributed to the development of quantum control theory and models for neural information processing. He has enjoyed fruitful collaborations with scientists working in twenty-five different countries and has held visiting positions at the Niels Bohr Institute, the University of Koeln, Aabo Akademi, the Instituto di Cibernetica at Arco Felice, the University of Cape Town, Los Alamos and Argonne National Labs, the Institute for Advanced Studies in Basic Sciences in Zanjan, and numerous other institutions. He has been a member of the external advisory committees of the Centro de Fisica Teorica at the University of Coimbra and the Zanjan Institute in Iran. He has served as Vice Chair and Chair of the Selection Committee for the Wheatley Award of the APS.
An organizer or co-organizer of more than twenty-five international scientific meetings, he is a member of the standing Advisory Committee for the International Conferences on Recent Progress in Many-Body Theories (Chair, 1981-87) and has been a Trustee of the annual International Workshops on Condensed Matter Theories since 1985. A central aim of the CMT workshop series, now in its 30th year, is the promotion of communication and collaboration between scientists working in the developed and developing nations.