https://doi.org/10.1140/epjb/e2014-50033-5
Regular Article
Robust thermal quantum correlation and quantum phase transition of spin system on fractal lattices
1
Shandong Provincial Key Laboratory of Laser Polarization and
Information Technology, Department of Physics, Qufu Normal University,
Qufu
273165, P.R.
China
2
Department of Optoelectronic Engineering, Binzhou
University, Binzhou
256600, P.R.
China
a
e-mail: kongxm@mail.qfnu.edu.cn
Received: 15 January 2014
Received in final form: 11 April 2014
Published online: 11 June 2014
We investigate the quantum correlation measured by quantum discord (QD) for thermalized ferromagnetic Heisenberg spin systems in one-dimensional chains and on fractal lattices using the decimation renormalization group approach. It is found that the QD between two non-nearest-neighbor end spins exhibits some interesting behaviors which depend on the anisotropic parameter Δ, the temperature T, and the size of system L. With increasing Δ continuously, the QD possesses a cuspate change at Δ = 0 which is a critical point of quantum phase transition (QPT). There presents the “regrowth” tendency of QD with increasing T at Δ < 0, in contrast to the “growth” of QD at Δ > 0. As the size of the system L becomes large, there still exists considerable thermal QD between long-distance end sites in spin chains and on the fractal lattices even at unentangled states, and the long-distance QD can spotlight the presence of QPT. The robustness of QD on the diamond-type hierarchical lattices is stronger than that in spin chains and Koch curves, which indicates that the fractal can affect the behaviors of quantum correlation.
Key words: Solid State and Materials
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2014