The common denominator of his research was to go beyond the mean-field models in solving the so-called many-body theory that occurs in quantum Bose or/and Fermi systems, characterized by the presence of strong correlations among their components.

Such theories have opened up the modern many-body studies on strongly interacting Fermi systems, such as nuclear matter and Quantum fluids.

He attended the high school in Livorno, graduated in physics in 1968 from University of Pisa, and received his PhD degree in 1970 from the Scuola Normale Superiore.

Fantoni's research activity has been mainly devoted to quantum liquids of interest of nuclear and condensed matter phenomena typical of low temperature physics.

The common denominator of his research was to go beyond the mean-field models in solving the so-called many-body theory that occurs in quantum Bose or/and Fermi systems, characterized by the presence of strong correlations among their components.

In connections with this kind of research Stefano Fantoni founded in 2005 the first PhD school in Science and Society supported by both SISSA and the University of Milan.

He has also been a consultant of the National Science Foundation and of the European Commission in the framework of INTAS program; Italian delegate to the OECD Committee Megaforum Science in Nuclear Physics in 1997 and 1998; member of the Program Advisory Committee for the Jefferson Laboratory at Newport News in Virginia from 1989 to 1993, when the accelerator was still under construction and the center began to outline its strategic lines of experimental research; member and then chairman of the Program Advisory Committee of INFN laboratories in Legnaro (Padova) in the period 1991–1996; member of the board of directors of the European Center for Theoretical Studies in Nuclear Physics and related areas (ECT*[7]) in 1993, when it was founded in Villazzano (Trento), until 1995; during the period 2003/2009 he was member of the International Advisory Committee of the Institute for Advanced Studies, Collegium Budapest.

In the period 1992–1993 Stefano Fantoni took part, as Italian member, together with the Danish nobelist Ben Mottelson and the French scientist Oriol Bohigas, in the Committee nominated to establish the European Centre for Theoretical Physics, ECT*.

For his contributions to theoretical nuclear physics and for the development of FHNC theory he has awarded the prestigious international recognition Eugene Feenberg Memorial Medal 2007.