In the recent years, nanoscale waveguides have become more and more popular as a way to enhance the atom-photon interaction. The emergent waveguide-QED framework makes use of the tight transversal confinement of light to improve the interaction strength for large number of atoms. Our experiment in LKB is based on a two-color dipole trap scheme that allows us to interface cold Cesium atoms with the evanescent field of a tapered optical nanofiber. An important feature of our trap scheme is that it allows us to place the atoms in a 1D lattice configuration, with control on the inter-atomic distance.
Our recent work is focused on the study of collective behaviours of such 1D lattices. On the theory side, I will briefly present our detailed study of the time dynamics of a single collective excitation in the presence of atomic Bragg mirrors, both in the Markovian and non-Markovian regime. On the experimental side, a strong motivation has been to reach quantum non-linearity at few-photon levels, and to control the propagation of single photons with powers close to the single photon regime in cavity-free setups. I will present our latest experimental results on all-optical bidirectional routing of a single photon using atomic Bragg mirrors. I will show that we can perform this routing with a control field power at the few hundred photons level.
