### TPSC seminar

Date and time: 20 September 2013 (Friday), 4:00 pm

Venue: Seminar Hall

**Title:** Exploring parity-time symmetry in optics

**Speaker:** Dr. Amarendra Kumar Sharma, Dept. of Physics, IIT, Gauhati

**Abstract:** Non-Hermitian quantum mechanics based on parity-time (PT) symmetry was proposed by Bender and Boettcher more than a decade ago. Since then, the study of parity-time symmetry have been explored quite extensively in many areas of theoretical physics including quantum field theory, even though experimental realization of such systems in quantum mechanics is yet to be found. However, recently it has turned out, after the experimental demonstration of PT-symmetry in a coupled waveguide system and optical mesh lattices, that optics may provide enough insight into the mechanism of PT-symmetry along with enormous possible applications. In this talk, I will discuss the concept of PT-symmetry in optics, from the first principle. Then I will discuss our recent work on the closed form PT-symmetric quadrimer optical waveguide structure. And finally, I will discuss our latest investigation on Schrodinger equation with a new class of nonlinearity which respects parity and time symmetry. I will show that such parity-time-symmetric nonlinear Schrodinger equation (PTNLSE) behaves fundamentally different than the standard nonlinear Schrodinger equation (NLSE). In particular, it can support both the bright and dark solitons at the same time. I hope this talk would be useful to researchers working in the area of nonlinear physics and nonlinear optics.