TsironisProf. George Tsironis
Professor, Department of Physics, University of Crete & Visiting Fellow, SEAS, Harvard University
Wave propagation in complex media: extreme events, branching and chimeras
Thursday, November 2, 2017, 2:00pm to 3:00pm | Room 5-314

Wave propagation in complex media involves extreme phenomena such as branching and rogue-type waves. We focus on both discrete and continuous systems; in the discrete case the systems are nonlinear [1] while in the continuous one are made of gradient index lenses that provide strong scattering [2]. We investigate the statistics of extreme events and find the features that lead to rogue wave formation. In the continuous case of a disordered linear medium we find that while nonlinearity does not seem to be very important, strong scattering is a necessary condition for extreme events [3]. We also investigate the onset of branching in electronic flows and show that in the ultra-relativistic case, applied to doped graphene, a specific relation for the first passage to the branching regime as a function of surface disorder exists that may be discernible experimentally. Finally we discuss the onset of partial coherence in complex media and show that turbulent chimeras may result in the discrete limit [4].

[1] Extreme events in discrete nonlinear disordered lattices, A. Maluckov, Lj. Hadzievski, N. Lazarides, G.P. Tsironis, Phys. Rev. E 79, 025601 (2009).
[2] M. Mattheakis, G. P. Tsironis, Extreme waves and branching flows in optical media, In: J.F.R. Archilla, N. Jimènez, V.J. Sànchez-Morcillo, L.M. Garcı̀a-Raffi (eds.). Quodons in mica: Nonlinear localized travelling excitations in crystals, Springer series in materials science pp 425-454 (2015).
[3] M. Mattheakis, I. J. Pitsios, G. P. Tsironis and S. Tzortzakis, Extreme events in complex linear and nonlinear photonics media, Chaos, Solitons and Fractals, 84, 73 (2016).
[4] J. Shena, J. Hizanidis, V. Kovanis, and G. P. Tsironis: Turbulent chimeras in large semiconductor laser arrays, Scientific Reports 7, 42116 (2017).

Short Bio

Giorgos P. Tsironis is a professor in the Department of Physics of the University of Crete in Greece and currently visiting fellow in the School of Engineering and Applied Sciences of Harvard University. He obtained his PhD in Theoretical Condensed Matter and Statistical Physics from the University of Rochester, NY in 1987. He was a postdoctoral associate in the University of California San Diego (1987-89) and the Fermi National Accelerator Lab (1989-91), and assistant professor of Physics at the University of North Texas (1991-94) while also affiliated with the Superconducting Super Collider Laboratory (1991-1993). He joined the Department of Physics of the University of Crete in 1994 as associate professor and became professor in 2000. He was visiting professor in the University of Barcelona in Spain (2000-1 and 2006-7) and professor in Nazarbayev University in Kazakhstan (2014-15). He has served as director of the Computing Center of the University of Crete (2003-09), chair of the Department of Physics, University of Crete (2007-2011), acting chair of the Department of Physics, Nazarbayev University (2014-15) and deputy rector of the University of Crete (2016-17). His research focuses on complexity, nonlinear phenomena and statistical physics with emphasis in applications. His current interests include superconducting and quantum metamaterials. He has published over 160 papers in refereed journals.