Telecom-Band Quantum Optics with Ytterbium Atoms and Silicon Nanophotonics

Wavelengths in the telecommunication window (approximately 1.25-1.65 μm) are ideal for quantum communication due to low transmission loss in fiber networks. To realize quantum networks operating at these wavelengths, long-lived quantum memories that couple to telecom-band photons with high efficiency need to be developed. We propose coupling neutral ytterbium atoms, which have a strong telecom-wavelength transition, to a silicon photonic crystal cavity. Specifically, we consider the P03↔3D1 transition in neutral Yb171 to interface its long-lived nuclear spin in the metastable P03 "clock" state with a telecom-band photon at 1.4μm. We show that Yb atoms can be trapped using a short-wavelength (approximately 470 nm) tweezer at a distance of 350 nm from the silicon photonic crystal cavity. At this distance, due to the slowly decaying evanescent cavity field at a longer wavelength, we obtain a single-photon Rabi frequency of g/2π≈100 MHz and a cooperativity of C≈47 while maintaining a high photon collection efficiency into a single mode fiber. The combination of high system efficiency, telecom-band operation, and long coherence times makes this platform well suited for quantum optics on a silicon chip and long-distance quantum communication.