Recent years have seen an explosion of research in microwave quantum optics where various Josephson junction devices provide the non-dissipative nonlinearity that is required for the most interesting quantum optical phenomena. This is an interesting return to the origins of the field where both masers and the first experiments by Hanbury-Brown and Twiss were performed in the microwave regime before their optical analogs were realised. Despite Maxwell, the analogy between the physics of the microwave and optical regimes of quantum electrodynamics has not always been as clear as it should be, so this research provides the opportunity to remind ourselves that all photons really are created equal. In this talk, A/Prof. Andrew Doherty will describe some of this recent work on superconducting circuits in the context of the history of quantum optics. As an example he will describe his recent work on analogs of parametric down conversion of photon pairs in a system known as the dynamical Coulomb blockade.