Waveguide-mediated interaction of artificial atoms in the strong coupling regime, part 1

Embedding of multiple quantum emitters to a common one-dimensional radiation channel gives rise to emergent collective effects: collective emission and long-range exchange interaction. Collective emission leads to super- and sub-radiant states while the signature of exchange interaction, coherent cooperative dynamics, has been obscured by the radiative decay into the one-dimensional channel. In this work, we utilize the sub-radiant state to trap the radiation, acting as an atomic cavity, and strongly couple a probe quantum emitter to the sub-radiant state, effectively creating an atom-cavity system [New J. Phys. 15, 063003 (2012)]. We implement the scheme with transmon qubits coupled to a microwave coplanar waveguide. We discuss the building blocks and design of the qubit-waveguide system, and the characterization of individual waveguide-coupled qubits which highlights the requirements for observing coherent cooperative dynamics. arXiv:1809.09752