  We report on the demonstration of ion-photon entanglement and Bell inequality
violation in a system of trapped 138Ba+ ions. Entanglement between the Zeeman
sublevels of the ground state of a single 138Ba+ ion and the polarization state
of a single 493 nm photon emitted by the ion with a fidelity of $0.84\pm0.01$
was achieved, along with a Bell signal of 2.3, exceeding the classical limit of
2 by over eight standard deviations. This system is a promising candidate for a
loophole-free Bell inequality violation test as the wavelengths of the
transitions of 138Ba+ are in the visible region and thus suitable for long
range transmission over fiber optic cable.
