标题： 二聚自旋-s链中的二聚纠缠 显示英文标题

标题： Pair entanglement in dimerized spin-s chains

摘要： 我们通过自洽的成对平均场近似方法，研究了有限二聚化自旋 -$s$链在横向磁场中通过各向异性$XY$耦合相互作用的基态中的成对纠缠。 该方法不对成对态作先验假设，在成对耦合较弱的情况下，预测在成对分解场以下的强场中存在$2s$个不同的二聚化相，其间由自旋宇称破缺相分隔。 二聚化相导致近似的磁化和成对纠缠平台，而宇称破缺相则表现出弱成对纠缠但与系统其余部分的纠缠不可忽略。 这些预测得到了有限$s=1$和$s=3/2$链的精确结果的证实。 还表明，随着自旋$s$值的增大，通过负性测量的孤立对的纠缠在各向异性$XY$情况下迅速饱和，但在$XX$情况下随$s^{1/2}$增加，反映了不同的单自旋纠缠光谱。 显示英文摘要

摘要： We examine the pair entanglement in the ground state of finite dimerized spin-$s$ chains interacting through anisotropic $XY$ couplings immersed in a transverse magnetic field, by means of a self-consistent pair mean field approximation. The approach, which makes no a priori assumptions on the pair states, predicts, for sufficiently low coupling between pairs, $2s$ distinct dimerized phases for increasing fields below the pair factorizing field, separated by spin parity breaking phases. The dimerized phases lead to approximate magnetization and pair entanglement plateaus, while the parity breaking phases are characterized by weak pair entanglement but non-negligible entanglement of the pair with the rest of the system. These predictions are confirmed by the exact results obtained in finite $s=1$ and $s=3/2$ chains. It is also shown that for increasing values of the spin $s$, the entanglement of an isolated pair, as measured by the negativity, rapidly saturates in the anisotropic $XY$ case but increases as $s^{1/2}$ in the $XX$ case, reflecting a distinct single spin entanglement spectrum.