Europhysics Letters (EPL)
Topological quantum phase transition in the transverse Wen-plaquette model
Jing Yu, Su-Peng Kou, Xiao-Gang Wen
Abstract
In this paper we study the quantum phase transition between a quantum state with topological order and that without topological order (TQPT) in the transverse Wen-plaquette model. By mapping the transverse Wen-plaquette model onto the d =1 Ising model in a transverse field, some exact results of the TQPT are obtained. The transverse Wen-plaquette model undergoes a continuous TQPT which is characterized in terms of the expectation values of string operators. In particular, the duality relationship between open-string and closed-string is explored —the expectation value of closed-string operator and that of open-string operator play the role of "order parameter" and "disorder order parameter" of the topological order, respectively. At the critical point the "condensation" of both Z 2 vortex and Z 2 charge indicates that the TQPT is a new type of phase transition beyond the Landau-Ginzburg-Wilson paradigm.