Quantum correlation and phase transitions in a two-dimensional doubly decorated Ising-Heisenberg model
Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology Wuhan 430074, China
2 School of Physics, Huazhong University of Science and Technology - Wuhan 430074, China
Accepted: 24 June 2011
We investigate the pairwise quantum correlation, characterized by quantum entanglement (QE) and quantum discord (QD), of a two-dimensional Ising-Heisenberg model on a planar doubly decorated lattice. At zero temperature, the concurrence (a measurement of pairwise entanglement) and the QD are related to the correlation function qxx and the staggered magnetization δSz, respectively, and both of them indicate the quantum phase transition (QPT) of the system. However, in a finite-temperature phase transition, all the pairwise entanglement vanishes thus it fails to detect the critical temperature TC, while the derivative of QD diverges at TC. This shows clearly that QD can capture the signal of phase transition in a separable state, thus it has a broader scope of application than QE in detecting phase transitions.
PACS: 05.30.Rt – Quantum phase transitions / 05.50.+q – Lattice theory and statistics (Ising, Potts, etc.) / 03.65.Ud – Entanglement and quantum nonlocality (e.g. EPR paradox, Bell's inequalities, GHZ states, etc.)
© EPLA, 2011