Spin-State Teleportation and Tests of EPR Correlations Using 151 MeV Entangled Protons

Abstract

We discuss the feasibility of quantum spin-state teleportation in a three-proton system at an energy of 151 MeV, where, similarly to the low-energy case, a single Bell-state term dominates the proton-proton scattering matrix. We find that, in contrast to the low-energy regime, where unpolarized proton-proton scattering produces strongly entangled outgoing proton pairs, at higher energies a pair of protons, each with an energy of $151$~MeV, must be produced in an unpolarized, exclusive proton-deuteron breakup reaction under complete final-state-interaction kinematics. The subsequent interaction of one of the entangled protons with a polarized hydrogen target triggers, as in the low-energy case, the teleportation process, whereby the polarization of the target proton is transferred to the second member of the entangled pair within the very narrow angular region of strong entanglement centered around a laboratory scattering angle of $45^\circ$. We also find that scattering one member of a strongly correlated proton pair forming a Bell state from an unpolarized hydrogen target leads to Einstein-Podolsky-Rosen-like correlations between the polarization of the scattered proton and that of the unscattered second entangled proton. The polarization of the scattered proton varies with its scattering angle. An identical polarization, following the angular dependence of thepolarization of the first proton, is induced in the second member of the pair, whose initial polarization was zero and whose momentum remains unchanged. The sign of the polarization of the second proton is determined by the sign of the spin correlation in the Bell state.