{Cu3}单分子磁体在磁场中的热纠缠

本文研究单分子磁体Na₉Cu₃Na₃(H₂O)₉ (α-AsW₉O₃₃)₂]·26H₂O中三角自旋 环在磁场作用下的热纠缠性质, 利用数值计算求出任意两个Cu²⁺离子量子比特之间的配对纠缠度, 分别记为C₁₂, C₂₃和C₁₃. 研究结果表明, 磁场的方向和大小以及温度对配对纠缠度具有重要影响, 而且参数的变化对C₁₂, C₂₃和C₁₃的影响也是各不相同. 给出外加三个不同方向的磁场时, 配对纠缠度C₁₂, C₂₃和C₁₃各自对应的临界温度T_c随磁场强度的变化图, 由此可以得到单分子磁体三角自旋环中存在纠缠态的参数范围. 通过选择适当的磁场方向和大小以及温度等实验参数, 可以有效地调节和提高单分子磁体中的配对纠缠度. 关键词： 配对纠缠 单分子磁体 三角自旋环

Thermal entanglement in a{Cu3}single molecular magnet in the magnetic field

We have investigated the properties of thermal entanglement in a triangular spin ring of the single molecular magnet (SMM) Na₉Cu₃Na₃(H₂O)₉ (α-AsW₉O₃₃)₂]·26H₂O in a magnetic field, and the pairwise concurrences of arbitrary two Cu²⁺ ion qubits are calculated numerically, hereafter abbreviated as C₁₂, C₂₃ and C₁₃, respectively. Results show that the magnitude and direction of magnetic field as well as temperature have important effects on the pairwise thermal entanglement. Moreover, C₁₂, C₂₃ and C₁₃ have difference variations with the change of the parameters. We also plot the changes of the critical temperatures T_c of C₁₂, C₂₃ and C₁₃ with the magnetic fields along three different directions, and from the critical temperature-magnetic field phase diagrams one can obtain the ranges of parameters in which the pairwise thermal entanglement in a triangular spin ring of the SMM exists. Therefore, the pairwise entanglement can be controlled and enhanced in the SMM by choosing appropriate magnitude and direction of magnetic field and temperature.
Keywords： pairwise entanglement single molecular magnet triangular spin ring