Abstract

We consider the remote state restoring and perfect transfer of the zero-order coherence matrix (PTZ) in a spin system governed by the XXZ-Hamiltonian conserving the excitation number. The restoring tool is represented by several nonzero Larmor frequencies in the Hamiltonian. To simplify the analysis we use two approximating models including either step-wise or pulse-type time-dependence of the Larmor frequencies. Restoring in spin chains with up to 20 nodes is studied. Studying PTZ, we consider the zigzag and rectangular configurations and optimize the transfer of the 0-order coherence matrix using geometrical parameters of the communication line as well as the special unitary transformation of the extended receiver. Overall observation is that XXZ-chains require longer time for state transfer than XX-chains, which is confirmed by the analytical study of the evolution under the nearest-neighbor approximation. We demonstrate the exponential increase of the state-transfer time with the spin chain length.

中文翻译：

---

XXZ-哈密尔顿状态转移中远程状态恢复的一些方面

 抽象的

我们考虑在由激发数守恒的 XXZ-哈密尔顿控制的自旋系统中零阶相干矩阵 (PTZ) 的远程状态恢复和完美传递。恢复工具由哈密顿量中的几个非零拉莫尔频率表示。为了简化分析，我们使用两个近似模型，包括拉莫尔频率的逐步或脉冲型时间依赖性。研究了最多 20 个节点的自旋链的恢复。在研究 PTZ 时，我们考虑了锯齿形和矩形配置，并利用通信线路的几何参数以及扩展接收器的特殊酉变换来优化 0 阶相干矩阵的传递。总体观察结果是，XXZ 链比 XX 链需要更长的状态转移时间，这通过最近邻近似下的演化分析研究得到证实。我们证明了状态转移时间随着自旋链长度呈指数增长。