His research interests are in the general areas of dynamical systems and mathematical physics, with the main focus being on the geometry of integrable Hamiltonian systems and the dynamics of coupled oscillator networks. He has published a monograph on integrable Hamiltonian systems and his research has appeared prestigious journals. His teaching interests at Duke Kunshan include foundational and advanced mathematics, with an emphasis on teaching innovation and student activation and inclusion.
Over a 14-year teaching career, he has taught mathematics and physics courses at introductory and advanced levels, and has received a best teacher award for his Calculus for Chemistry course.
Efstathiou has a B.Sc. and M.Sc. in physics from the University of Athens, Greece, and a Ph.D. (highest distinction) in physics from the Universite Littoral Cote d'Opale, France. He also has an Undergraduate Teaching Qualification. Before joining Duke Kunshan, he was an assistant professor at the University of Groningen, the Netherlands. In 2012 and 2013, he was a lecturer in the Department of Mathematical Sciences, Xi'an Jiaotong Liverpool University, where he also served as acting head of department.