Systematic design of a novel photonic crystal waveguide platform for coupling guided light with trapped cold atoms

Reaching a regime of strong coupling between light and atoms is a long-sought goal in quantum optics, as it will enable non-linear optics at the photon level. Interfacing atoms with guided light in nanophotonic waveguides is a promising route to achieve such regimes. Experimental platforms include nanofibers [1] and photonic crystal waveguides (PCWs), owing to the large transverse confinement of their guided modes. With PCWs, tuning the dispersion relation gives rise to the additional benefit of a very low group velocity of the guided light [2] , allowing for strong coupling even in single pass. Moreover these systems can help explore waveguide-QED and probe exciting novel bandgap physics [3] . While encouraging values of couplings have been observed with first corrugated devices [4] , a photonic platform with trapped atoms via guided modes in the vicinity of a waveguide and lying deep in the strong coupling regime has yet to be demonstrated.