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

TL;DR

This paper studies how local quantum dynamical processes affect quantum state transfer in spin chains, revealing interference effects, finite propagation speeds, and differences between unitary and non-unitary interventions in integrable and non-integrable systems.

Contribution

It introduces analysis of interference effects of local quantum processes on state transfer in both integrable and non-integrable spin chains, highlighting differences between unitary and non-unitary dynamics.

Findings

State transfer fidelity decreases with distance from the coding site.

Non-unitary QDP causes small changes in fidelity.

Unitary QDP can significantly enhance fidelity at certain sites and times.

Abstract

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 non- unitary QDP intervening the background unitary dynamics. In the case of unitary QDP, the change is more pronounced, with a substantial increase in the fidelity for appropriate sites and times. For the non-integrable case, viz. a kicked Harper model, the state transfer fidelity is quite large for further sites for short times, indicating a finite speed for the propagation of the quantum correlation cannot be defined.