交错Dzyaloshinskii-Moriya相互作用对反铁磁Heisenberg链纠缠的影响

Effects of the staggered Dzyaloshinskii-Moriya interaction on entanglement in antiferromagnetic Heisenberg chain

主要研究了具有交错Dzyaloshinskii-Moriya(DM)相互作用的反铁磁Heisenberg链的纠缠.基于density-matrix renormalization group(DMRG)的数值计算表明,交错DM相互作用消除了系统在外磁场H=2处的二级量子相变,从而量子纠缠反常行为也随之消失;同时纠缠范围的发散也被消除,意味着该模型因子化点的消失.交错DM相互作用导致系统在任意强场下也不会达到铁磁饱和状态,从而保持着自旋纠缠.交错DM相互作用有利于通过外场调控纠缠程度和纠缠范围.

By using the density-matrix renormalization group method, the spin entanglement in the antiferromagnetic Heisenberg chain with the staggered Dzyaloshinskii-Moriya （DM） interactions is investigated. It is found that the staggered DM interactions remove the field-induced second order quantum phase transition of the system at the magnitude of magnetic field H=2, and lead to the vanishing of the anomalous behavior of quantum entanglement. Also, the staggered DM interactions eliminate the divergence of entanglement range. It means the disappearance of the factorizing point in the model studied. Due to the presence of the staggered DM interactions, the system will never come to the state of saturated ferromagnetism under finite magnetic fields, thus maintaining the spin entanglement. The staggered DM interactions favor the tuning of the strength and range of spin entanglement.