## Relaxation dynamics, thermalization, and dynamic phase transitions in Heisenberg quantum magnets

**Note:**11 AM

**Speaker:**Dr. Michael Knap, Harvard University

**When:**November 12, 2014 (Wed), 11:00AM to 12:00PM (add to my calendar)

**Location:**SCI 328

**Hosted by:**Marin Bukov

*This event is part of the Condensed Matter Theory Seminar Series. *

Abstract:

Recent advances in experiments with synthetic many-body systems, including ultracold atoms, trapped ions, and polar molecules, made it possible to engineer strongly interacting quantum spin systems and to explore their dynamics. Drawing connections to recent experiments, this talk addresses the question of how a spin spiral pattern with adjustable wave vector evolves under the Heisenberg model. To understand the evolution theoretically, we develop a field theoretic technique based on the two-particle irreducible (2PI) effective action approach which is applicable in arbitrary dimension. We analyze the relaxational dynamics of the spin spiral state and study how it thermalizes in the long time limit. In three dimensions, we find that the transverse magnetization at steady state takes a finite value when tuning the spiral wave vector beyond a critical value, thus indicating a dynamic phase transi