Events
Forging the topological states
25 April 2022
Eastern Time (US & Canada) (UTC -05:00)
Topological states in Hermitian systems are known for their robustness against the disorders and their localization at the edge or surface of a finite structure with nontrivial topology. While such a picture is still valid in non-Hermitian systems new features such as skin effect and delocalization arise in those systems which allows for extra possibilities for engineering the topological robust states. Despite these new possibilities still, the control over topological states is very limited. For example, topological robust states are localized as their energy is located inside the gap. For practical applications, such as a topological laser, for instance, it would be beneficial if one can generate a topological state that is not localized, or its energy is not located in the gap. In my talk, I will demonstrate the observation and origin of robust bulk states in a disordered non-Hermitian system. In contrast to topological edge states, the robust bulk states are distributed all over the system and thus allow us to access the whole system. This subject opens a new direction for a new form of robust states that are not necessarily localized on one side of the system.
About Our Speaker: Hamidreza Ramezani, UTRGV
Dr. Ramezani, an early career member of OPTICA, is an associate professor in the Department of Physics and Astronomy at the University of Texas Rio Grande Valley (UTRGV). He is the recipient of STAR awards from the UT System, the Biruni award from the Iranian-American Physicists(IrAP) Network Group, and the COS excellent award in research at UTRGV. He is among the pioneers in the field of non-Hermitian photonics and acoustics, the so-called Parity-Time symmetric systems with more than 50 publications on this topic including the unidirectional invisibility, selected as a breakthrough by IEEE in 2011, and non-reciprocal localization of light, selected as editor suggestion in Phys. Rev. Lett., to name a few.
