1304.7362 (H. L. Huang et al.)

Odd-even effect of quantum discord and quantum phase transitions in the
S=1/2 spin ladder with ring exchange    [PDF]

H. L. Huang, Z. Y. Sun, B. Wang

The singularity of quantum correlations, such as quantum entanglement(QE) and quantum discord(QD), has been widely regarded as a valuable indicator for quantum phase transition(QPT) in low-dimensional quantum systems. In this paper, for a spin ladder system with ring exchange, we find that the singularity of QD (or QE) could not indicate the critical points of the system. Instead, the QD shows a novel odd-even effect in some phases, which can be used to detect the phase boundary points. The size effect is related to the symmetry breaking of the ladder.

View original: http://arxiv.org/abs/1304.7362