Entanglement of three-qubit spin states moving in the gravitational field of a massive body

Abstract

We study the spin entanglement of a tripartite system consisting of spin- particles in the GHZ and W spin states with and without momentum correlations moving in the gravitational field of a massive body. Considering circular motions of the system around the body, we use spin fidelity as a measure of the change in spin entanglement due to orbiting and describe its behavior as a function of the orbiting velocity and path radius. We find that in the GHZ state momentum correlation always elevates spin entanglement, whereas in the W state it can yield degradation depending on the orbiting velocity. Furthermore, there is a unique circular orbit that leaves the spin entanglement unchanged for both spin states irrespective of the momentum state and orbiting velocity.