Between 1987 and 1998, Barbu was a research fellow at the University of Bucharest's Institute of South-Eastern European Studies, that became an institute of the Romanian Academy in 1990. After the
Romanian Revolution of 1989, he completed his Ph.D. in art history at the
University of Cluj-Napoca in 1991, his thesis was on
Artistic relations between Romanian countries and the Veneto-Cretan school in the 16th century. Between 1990 and 1991, he was head of
Editura Meridiane, a Bucharest-based publishing house. He was also general director of
Realitatea Românească, a daily newspaper, in 1991–1992. He then went to Switzerland, where he took doctoral studies in Catholic theology at the
University of Fribourg until 1993. He was also a guest researcher at the
Pontifical Oriental Institute in Rome. In the same year, he was appointed associate professor
(Conferențiar universitar) at the University of Bucharest. Barbu was the Dean of the Faculty of Political Science (and Public Administration) of the University of Bucharest from 1994 to 2000 and from 2002 to 2004. In 1997 he was promoted to a full professorship. In 1999, he took a second doctorate, in philosophy, from the University of Bucharest, and received the
habilitation (Abilitare) in political science. In the same year, he took over as director of the Institute for Political Research of the University of Bucharest, a position he held until 2011. From 2004 to 2010, he chaired the Department of political science and from 2004 to 2011 he served as director of the university's Graduate school of political science. He was appointed to the scientific board of the
Institute for the Investigation of Communist Crimes and the Memory of the Romanian Exile in 2014. In the following year, Barbu earned a third doctorate, in theology, from the University of Bucharest. Barbu was a visiting professor at the
School for Advanced Studies in the Social Sciences (EHESS) in Paris (1995), the
National and Kapodistrian University of
Athens (2000),
University of Pittsburgh (2001),
Jackson State University (2002),
Institut d'études politiques de Bordeaux (2004),
Central European University in Budapest (2005), and
Sciences Po Aix (2009). Barbu specialised in the comparative history of European civilizations, political science and comparative political science, social and political models of the state, minorities and confessional groups in Romania, constitutions, government and politics in Europe, totalitarian regimes, communism and state-socialism, and political anthropology. == Politics ==