Physical model for the generation of ideal resources in multipartite quantum networking

We propose a physical model for generating multipartite entangled states of spin-$s$ particles that have important applications in distributed quantum information processing. Our protocol is based on a process where mobile spins induce the interaction among remote scattering centers. As such, a major advantage lies in the management of stationary and well-separated spins. Among the generable states, there is a class of $N$-qubit singlets allowing for optimal quantum telecloning in a scalable and controllable way. We also show how to prepare Aharonov, $W$, and Greenberger-Horne-Zeilinger states.

Figure 1

Sketch of the physical proposal. Unpolarized mobile particles $e$’s undergo scattering from a linear array of $N$ static spins. When these are spaced in a way so as to satisfy the resonance conditions of the problem and initially prepared in a suitable product state, successive records of the mobile particles in the transmission channel extract an $N$-partite singlet state of the scattering centers.

Figure 2

(a) Fidelity of singlet-state extraction against the number $\nu$ of mobile particles launched into the scattering region. (b) The success probability of the scheme. The empty circles show the case corresponding to $N=2$ spin-1/2 scattering centers, the filled squares are for $N=4$, while the filled circles refer to $N=6$. The centers are initially prepared in the state (3), whereas spin-spin interaction under RCs occurs via Eq. (1) with $J=2$.