In this talk, I will address key aspects of coherent light-matter interaction that are intimately tied to the development of cavity and circuit quantum electrodynamics (QED) since the discovery of the laser. These developments have decisively shaped the modern evolution of quantum information and computation, as we progressively access single-atom operations on a fully quantum level. When following this route, we find that the open driven Jaynes-Cummings (JC) model occupies a central role. I will reveal this role by highlighting the significance of quantum fluctuations against the predictions of mean-field theory in three distinct regimes of operation, determined by the interplay of quantum and classical dynamics. To set the stage, I will demonstrate the persistence of photon blockade, predicted in [H. J. Carmichael, Phys. Rev. X 5, 031028 (2015)]. I will then focus on the onset and collapse of instability in the weakly-driven JC model, before moving to the region of high-amplitude nonlinearity, when one speaks of a dissipattive quantum phase transition. To close out, I will present results from two beautiful experiments in the strong-coupling regime of QED, realized over the last five years, pointing to single-photon sources and photon-photon gates.
Themis(toklis) Mavrogordatos received the BS and MS degrees in electrical engineering and computer science from the National Technical University of Athens, Greece, in 2009, and the PhD degree in emission properties of dye-doped liquid crystal resonators from the University of Cambridge, UK, in 2014. Following two postdoctoral appointments at the University College London in optomechanics and circuit quantum electrodynamics, he worked with Jonas Larson at Stockholm University, with whom he also co-authored a monograph on the Jaynes-Cummings model, published by IOP. He is currently a Severo Ochoa postdoctoral fellow working on quantum trajectories upon joining the group led by Maciej Lewenstein at ICFO (Barcelona, Spain) in spring 2022.