"We plan to investigate the strong coherent interaction of light and matter on the level of individual photons and atoms or atom-like systems. In particular, we will explore large dipole moment superconducting artificial atoms and natural Rydberg atoms interacting with radiation fields contained in quasi-one-dimensional on-chip microwave frequency resonators. In these resonators photons generate field strengths that exceed those in conventional mirror based resonators by orders of magnitude and they can also be stored for long times. This allows us to reach the strong coupling limit of cavity quantum electrodynamics (QED) using superconducting circuits, an approach known as circuit QED. In this project we will explore novel approaches to perform quantum optics experiments in circuits. We will develop techniques to generate and detect non-classical radiation fields using nonlinear resonators and chip-based interferometers. We will also further advance the circuit QED approach to quantum information processing. Our main goal is to develop an interface between circuit and atom based realizations of cavity QED. In particular, we will couple Rydberg atoms to on-chip resonators. To achieve this goal we will first investigate the interaction of ensembles of atoms in a beam with the coherent fields in a transmission line or a resonator. We will perform spectroscopy and we will investigate on-chip dispersive detection schemes for Rydberg atoms. We will also explore the interaction of Rydberg atoms with chip surfaces in dependence on materials, temperature and geometry. Experiments will be performed from 300 K down to millikelvin temperatures. We will realize and characterize on-chip traps for Rydberg atoms. Using trapped atoms we will explore their coherent dynamics. Finally, we aim at investigating the single atom and single photon limit. When realized, this system will be used to explore the first quantum coherent interface between atomic and solid state qubits."