Floquet Topological Quantum Phase Transitions in the transverse Wen-Plaquette Model

Date & Time
6 February 2013 (Wed.) 15:00-16:00
4F room 409/410, Collaborative Bldg., Namiki site
Mr. Victor Manuel Bastidas Valencia
Institut fuer Theoretische Physik, Technische Universitaet Berlin
Floquet Topological Quantum Phase Transitions in the transverse Wen-Plaquette Model
Symmetry breaking is a paradigm of condensed matter physics in which the states of matter are characterized as symmetry broken phases. However, rather recently, novel states of matter have been discovered, a topological quantum phase transition (TQPT), which cannot be classified inside the Landau criteria. Topological states of matter are characterized by an intrinsic robustness against the effects of an environment as a consequence of the topological properties of the ground state.
The current feasibilities of the experimental methods to control and simulate quantum many-body systems allow to experimentally explore the nonequilibrium dynamics of systems under the effect of an external driving. In particular, this opens the possibility to investigate spin systems with topological order in nonequilibrium, which have a huge potential for applications in quantum information technologies as topologically-protected qubits.
In this talk I will discuss the TQPT in a spin model termed Wen-plaquette model (WPM) in a time-dependent transverse field. In the absence of driving, the transverse WPM exhibits a TQPT from a spin-polarized phase to a topologically-ordered phase. I will discuss generalized ``string''-like topological order parameters by considering cycle-averaged expectation values of string operators in a Floquet state.
Dr. Junichi Inoue(井上純一)