Integrating cold atoms into optical waveguides

Hybrid quantum devices, incorporating both atoms and photons, can exploit the benefits of both to enable scalable architectures for quantum computing and quantum communication, as well as chip-scale sensors and single-photon sources. Production of such devices depends on the development of an interface between their atomic and photonic components. This should be compact, robust and compatible with existing technologies from both fields. We have previously demonstrated a compact interface that enables the interaction of cold Caesium atoms with resonant photons and now we plan to demonstrate Electromagnetically Induced Transparency (EIT) of Caesium atoms in a fibre. For this atoms are cooled in a magneto-optical trap and transferred to an optical dipole trap. Previously, these atoms were then positioned inside a transverse, 30 µm diameter through-hole in an optical fibre, created via laser micromachining. We trapped about 300 atoms at a temperature of 70µK. When the guided light is in resonance with the Caesium D2 line, up to 87% of it was absorbed by the atoms. We hope to improve on this setup and then begin implementing EIT. Our technique should be equally effective in optical waveguide chips and other existing photonic systems.