Issue
EPL
Volume 84, Number 1, October 2008
Article Number 17004
Number of page(s) 5
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
DOI http://dx.doi.org/10.1209/0295-5075/84/17004
Published online 18 September 2008
EPL, 84 (2008) 17004
DOI: 10.1209/0295-5075/84/17004

Topological quantum phase transition in the transverse Wen-plaquette model

Jing Yu1, Su-Peng Kou1 and Xiao-Gang Wen2

1   Department of Physics, Beijing Normal University - Beijing 100875, China
2   Department of Physics, Massachusetts Institute of Technology - Cambridge, MA 02139, USA

spkou@bnu.edu.cn

received 10 June 2008; accepted in final form 25 August 2008; published October 2008
published online 18 September 2008

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 Z2 vortex and Z2 charge indicates that the TQPT is a new type of phase transition beyond the Landau-Ginzburg-Wilson paradigm.

PACS
75.10.Jm - Quantized spin models.
05.70.Jk - Critical point phenomena.

© EPLA 2008