Subsystem complexity after a global quantum quench

Understand

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.