Doubly ionized lanthanum as a qubit candidate for quantum networks

Abstract

We propose doubly-ionized lanthanum (La$^{2+}$) as a possible qubit candidate for quantum networks. Transitions between the lowest levels in the atom are in the infrared, enabling a direct matter-light interface amenable to long-distance quantum communication. These transitions could also be used to directly laser-cool trapped La$^{2+}$ ions. The rich hyperfine structure of the ion may allow for a qubit stored in magnetic-field insensitive states, as well as protocols for atom-photon entanglement.