Speaker: Nuh Gedik (MIT)

Title: Capturing light induced phase transitions with femtosecond movies

Abstract: Materials typically undergo phase changes as a function of external parameters such as temperature, pressure or magnetic field. Light can also be used to both switch between equilibrium phases and to create new photo-induced states that may have no equilibrium counterparts. Even though there are fascinating examples of photoinduced phase transitions, the detailed microscopic mechanisms and overarching principles that govern these are still not known. In this talk, I will describe how we used ultrashort laser pulses to capture light induced melting and recovery of a charge density wave phase with femtosecond time resolution. During this process, a new state that does not exist in equilibrium is also transiently created. In a different material, I will show how circularly polarized light can induce and detect a chiral phase of electrons. Understanding light induced phase transitions could pave the way for optical engineering of new quantum states of matter.

Bio:
Professor Gedik joined the MIT Physics Department as an assistant professor in January 2008. He received his B.S. in Physics in 1998 from Bogazici University, Istanbul, Turkey and his Ph.D in Physics in 2004 from University of California, Berkeley. After his Ph.D, he moved to Caltech where he worked as a postdoctoral scholar till January 2008. His awards include National Science Foundation CAREER Award, Department of Energy Early Career Award, Sloan fellowship, DARPA Young Faculty Award and Moore Experimental Investigator award. He was promoted to Full Professor of Physics in 2018.