次近邻相互作用对Heisenberg XX链纠缠影响的研究(英文)

Effects of the Next-Nearest-Neighbor Interaction on the Entanglement of the Heisenberg XX Chain

研究了存在次近邻相互作用(耦合)时Heisenberg XX链的纠缠特性．结果表明对近邻格点,随着耦合常数J的变化,次近邻相互作用的存在可能使其纠缠度增大或者减小;而对次近邻格点,引进次近邻相互作用却可以产生纠缠,并且使其随着|J|的增大而增大．近邻格点间纠缠存在的临界温度Tc随着J的增大而降低,次近邻格点间纠缠存在的临界温度Tc随着|J|的增大而升高．此外对纠缠W态的制备,次近邻相互作用的存在还使得三量子位情形时W态产生的时刻改变,而对于四量子位情形却没有影响．

The pairwise entanglement of the Heisenberg XX chain with next-nearest-neighbor （NNN） interactions was investigated by using the concurrence measure. The results show that for the nearest-neighbor sites, the entanglement may be improved or suppressed depending on the magnitudes of the NNN coupling constant J, while for the next-nearest-neighbor sites, it always increases with the increase of ｜J｜. The critical temperature Tc decreases with the increase of J for the nearest-neighbor entanglement and increases with the increase of ｜J｜ for the next-nearest-neighbor entanglement, respectively. We also show that the general Heisenberg XX model still can be used to create the entangled W states of three and four qubits, and that the presence of NNN coupling has no effect on the creation of four-qubit W states, while it shifts the instant of time at which the three-qubit W states are created.