不同磁场环境下Heisenberg XXZ自旋链中的热量子失协

本文研究了不同磁场环境下一维Heisenberg XXZ自旋链中两量子比特的热量子失协特性. 在四种不同的磁场环境下: 1) B₁=B₂=0 (无磁场); 2) B₁≠0, B₂=0 (磁场只作用于其中一个量子比特); 3) B₁=B₂ (均匀磁场); 4) B₁=-B₂ (非均匀磁场), 对分别作用在每个量子比特上的磁场B₁和B₂对其量子关联的影响作了详细的讨论, 且数值计算和比较了其量子失协和量子纠缠的异同. 结果显示: 在有限温度下, 量子失协相比于量子纠缠更普遍, 且非均匀磁场相比于均匀磁场对量子失协和量子纠缠更有用, 更有利于量子通讯和量子信息处理过程.关键词：量子关联纠缠量子失协

Thermal quantum discord in Heisenberg XXZ model under different magnetic field conditions

The quantum discord of a two-qubit one-dimonsional Heisenberg XXZ spinchain in thermal equilibrium depends on the temperature T, when subjected to different magnetic fields, with B₁ and B₂ acting separately on the qubit, is studied in this paper. Four cases are considered here: (1) B₁=B₂ = 0 (without magnetic field); (2) B₁≠0,B₂=0 (only one qubit in magnetic field); (3) B₁=B₂ (homogeneous magnetic field); (4) B₁=-B₂ (inhomogeneous magnetic field). The similarities and difference between quantum discord and quantum entanglement are calculated and discussed in detail. Results show that the quantum discord is more robust than quantum entanglement against temperature, and the effect of inhomogeneous magnetic field is preferable for the quantum communications and quantum information processing, as compared with the effect of homogeneous magnetic field.
Keywords：quantum correlationsentanglementquantum discord