We discuss the mechanism and the conditions for the appearance of synchronized charge oscillations which have been observed experimentally and theoretically after strong photoexcitation of dimerized systems. In the Hubbard model with on-site repulsion, the Bloch equations for a wave-number-dependent pseudospin — whose components describe the charge-density difference, current density, and bond density between the two sublattices — involve an alternatingly tilted pseudomagnetic field, which assists the synchronization of pseudospins with different wave numbers, irrespective of the initial condition. This fact is numerically confirmed by the dynamics in finite lattices based on the exact diagonalization method. In the presence of nearest-neighbor repulsion, however, the synchronization can be hindered by excitons. Therefore, the excitation of a sufficiently large density of free electron–hole pairs, but low density of excitons, is needed to achieve synchronization.

中文翻译：

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二聚体晶格中电荷振荡的同步机制

我们讨论了二聚体系的强光激发后通过实验和理论观察到的同步电荷振荡出现的机理和条件。在具有现场排斥力的Hubbard模型中，与波数相关的伪自旋的Bloch方程（其成分描述了两个子晶格之间的电荷密度差，电流密度和键密度）涉及交替倾斜的伪磁场，不管初始条件如何，都可以帮助同步具有不同波数的伪自旋。基于精确对角线化方法的有限晶格中的动力学在数值上证实了这一事实。但是，在最近邻排斥的情况下，激子会阻碍同步。所以，