一维二周期均匀Compass模型中的量子相变
Quantum phase transition in the one-dimensional period-two and uniform compass model
摘要：
利用赝自旋变换方法和迹映射方法研究了一维二周期均匀量子罗盘模型中的量子相变。给出了系统的精确解，计算了保真度、最近邻自旋纠缠、自旋和自旋关联函数。在临界点处，保真度和磁化率发生了显著变化，出现了赝自旋并发能隙，其尺度为$1/N$（N为系统尺寸）。自旋关联函数在临界点附近表现出平滑的行为。在周期为2的链中，赝自旋关联函数呈现出振荡行为，而在unform链中则没有这种现象。两种情况下，在临界点的发散相关长度表现在总的趋势。
英文摘要：
Quantum phase transition in the one-dimensional period-two and uniform quantum compass model are studied by using the pseudo-spin transformation method and the trace map method. The exact solutions are presented, the fidelity, the nearest-neighbor pseudo-spin entanglement, spin and pseudo-spin correlation functions are then calculated. At the critical point, the fidelity and its susceptibility change substantially, the gap of pseudo-spin concurrence is observed, which scales as $1/N$ (N is system size). The spin correlation functions show smooth behavior around the critical point. In the period-two chain, the pseudo-spin correlation functions exhibit a oscillating behavior, which is absent in the unform chain. The divergent correlation length at the critical point is demonstrated in the general trend for both cases.
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