Interference of the signal from a local dynamical process with the quantum state propagation in spin chains

The effect of a local instantaneous quantum dynamical process (QDP), either unitary or non-unitary, on the quantum state transfer through a unitary Hamiltonian evolution is investigated for both integrable and non-integrable dynamics. There are interference effects of the quantum state propagation and the QDP signal propagation. The state transfer fidelity is small for further sites, from the site where the information is coded, indicating a finite speed for the propagation of the quantum correlation. There is a small change in the state transfer fidelity for the case of the non-unitary QDP intervening in the the background of unitary dynamics. In the case of the unitary QDP, the change is more pronounced, with a substantial increase in the fidelity for appropriate sites and times. For the non-integrable case, namely a kicked Harper model, the state transfer fidelity is quite large for further sites for short times, indicating that a finite speed for the propagation of the quantum correlation cannot be defined.