Fast Photon-Mediated Entanglement of Continuously Cooled Trapped Ions for Quantum Networking
Jameson P. O'Reilly, George Toh, Isabella Goetting, Sagnik Saha, Mikhail I. Shalaev, Allison L. Carter, Andrew Risinger, Ashish Kalakuntla, Tingguang Li, Ashrit Verma, Christopher R. Monroe · Physical Review Letters · 2024
We entangle two cotrapped atomic barium ion qubits by collecting single visible photons from each ion through in vacuo 0.8 NA objectives, interfering them through an integrated fiber beam splitter and detecting them in coincidence. This projects the qubits into an entangled Bell state with an observed fidelity lower bound of F>94%. We also introduce an ytterbium ion for sympathetic cooling to remove the need for recooling interruptions and achieve a continuous entanglement rate of 250 s^{-1}.