Topological Entropy after a Quantum Quench

Speaker: Alioscia Hamma, Perimeter Institute for Theoretical Physics

When: May 22, 2013 (Wed), 02:00PM to 03:00PM (add to my calendar)
Location: SCI 328
Hosted by: Claudio Chamon

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

Abstract: We study the time evolution of a topologically ordered state after a Quantum Quench (QQ). We prepare the system in the ground state of the toric code and then suddenly switch on an external magnetic field. We study two QQs, one integrable and one non-integrable. In the first case, we give an exact treatment for the time evolution, while in the second one we resort to perturbation theory. We are interested in the notion of topological order away from equilibrium. To this goal, we use the topological part of the 2-Renyi entropy of the reduced state. We show that for both QQs, the topological entropy is resilient at large times, regardless of integrability. We argue that in order to disrupt topological order, the QQ needs also to break the gauge symmetry of the Hamiltonian.