Telecom-band quantum optics with ytterbium atoms and silicon nanophotonics

Abstract

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 ^3P_0↔^3D_1 transition in neutral ^(171)Yb to interface its long-lived nuclear spin in the metastable ^3P_0 “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.