Open systems with Parity-Time (PT) symmetry: theory and experiments

Conservation laws and their violations are ingrained in human expectations. Kids are surprised  when they see a rabbit pulled out of an empty hat, but don’t bat an eye when a rolling ball comes to a stop; intuitively, the distinction between isolated and open systems is clear to them. Recently, a special class of open systems called parity-time (PT) symmetric systems has engendered great interest. After an introduction to this field, which began here at Washington University, I will present the basic phenomenology of time-periodic and non-Markovian PT systems by using their realizations in ultracold atoms and coupled semiconductor lasers respectively. I will then discuss conservation laws and their consequences in such an open system; they are demonstrated with single-photon interferometry in a lossy, linear optical circuit. The talk will conclude with open questions raised by disparate, classical or quantum realizations of PT systems (and questions not yet asked). 

In collaboration with Le and Vemuri groups (IUPUI), Xue group (Beijing), Leon Montiel group (UNAM), Garcia Nustes group (Chile), Laing group (Bristol), and Murch group (Wash U).