Universality and robustness of revivals in the transverse field XY model

We study the structure of the revivals in an integrable quantum many-body system, the transverse field $XY$ spin chain, after a quantum quench. The time evolutions of the Loschmidt echo, the magnetization, and the single-spin entanglement entropy are calculated. We find that the revival times for all of these observables are given by integer multiples of ${T}_{\mathrm{rev}}\ensuremath{\simeq}L/{v}_{\mathrm{max}}$, where $L$ is the linear size of the system and ${v}_{\mathrm{max}}$ is the maximal group velocity of quasiparticles. This revival structure is universal in the sense that it does not depend on the initial state and the size of the quench. Applying nonintegrable perturbations to the $XY$ model, we observe that the revivals are robust against such perturbations: they are still visible at time scales much larger than the quasiparticle lifetime. We therefore propose a generic connection between the revival structure and the locality of the dynamics, where the quasiparticle speed ${v}_{\mathrm{max}}$ generalizes into the Lieb-Robinson speed ${v}_{\text{LR}}$.