Networking Ion Traps with Telecom-Compatible 88Sr+ Photons

Generating entanglement between distant trapped ions is necessary for realizing quantum networks and distributed computation on this platform. Current methods require sending ion-entangled photons down optical fibers between trapped ion nodes. It remains a technical challenge to do so with photons that exhibit low loss in fibers. Most ion transitions realizing the scheme emit at high-loss wavelengths, necessitating frequency conversion techniques to achieve appreciable networking distances, which can add noise and technical complexity. As an alternative, we use the P1/2 → D3/2 transition in 88Sr+. The transition emits at 1092 nm, a wavelength that has relatively low loss in standard telecom fibers. This makes the transition efficient for medium-distance quantum networking (~<10 km). We report on experimental results from our first network node coupling ion emissions into telecom fiber, characterizing loss, and measuring ion-photon entangled state fidelity.