We study the temporal evolution of the circuit complexity for a subsystem in harmonic lattices after a global quantum quench of the mass parameter, choosing the initial reduced density matrix as the reference state. Upper and lower bounds are derived for the temporal evolution of the complexity for the entire system. The subsystem complexity is evaluated by employing the Fisher information geometry for the covariance matrices. We discuss numerical results for the temporal evolutions of the subsystem complexity for a block of consecutive sites in harmonic chains with either periodic or Dirichlet boundary conditions, comparing them with the temporal evolutions of the entanglement entropy. For infinite harmonic chains, the asymptotic value of the subsystem complexity is studied through the generalised Gibbs ensemble.

我们研究了质量参数的全局量子猝灭后，选择初始降低的密度矩阵作为参考状态，从而研究了谐波晶格中子系统的电路复杂性随时间的演变。上限和下限是针对整个系统的复杂性的时间演变而得出的。通过对协方差矩阵采用Fisher信息几何来评估子系统的复杂度。我们讨论了具有周期或Dirichlet边界条件的谐波链中连续位置块的子系统复杂度的时间演化的数值结果，并将其与纠缠熵的时间演化进行了比较。对于无限次谐波链，通过广义的吉布斯合奏研究了子系统复杂度的渐近值。