Entangled spin states in geodesic motion around massive body

Paul M. Alsing, G. J. Stephenson, Patrick Kilian

We investigate in a covariant manner the spin-induced non-geodesic motion of massive spin 1/2 particles in an arbitrary gravitational field for trajectories that are initially geodesic when spin is ignored. Using the WKB approximation for the wave function in curved spacetime, we compute the O(hbar) correction to the Wigner rotation of the spin 1/2 particle, whose O(1) contribution is zero on timelike geodesics. We develop conditions for the motion of observers in which the Wigner rotation is null. For the spherically symmetric Schwarzschild metric, we consider specific examples of particle motion in the equatorial plane for (i) circular orbits and (ii) radially infalling trajectories. For the former case we consider the entanglement for a perfectly anti-correlated EPR entangled pair of spins as the separate qubits traverse the circular orbit in same direction.

Sofia Qvarfort, Sougato Bose, Alessio Serafini

A. Mohadi, N. Mebarki, M. Boussahel

In Schwarzschild-de Sitter space-time, the effect of a gravitational field near a massive body black hole on the spin entanglement has been studied for two-qubits in the case of triplet and singlet states of a two particles system in a circular geodesic motion. It is found that the effect of the cosmological constant on the robustness of the Wooters concurrence is more important in the triplet state than in the singlet one even in the extended region around the black hole

Zhisong Wang, L. C. Kwek, C. H. Lai +1 more

Fatemeh Ahmadi, Mohammad Mehrafarin

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.

Francesca Vidotto