Light–matter coupling with strength comparable to the bare transition frequencies of the system is called ultrastrong. This Review surveys how experiments have realized ultrastrong coupling in the… Expand

Analysis, based on a microscopic quantum theory, shows that the nonlinear polariton splitting, a signature of this regime, is a dynamical effect arising from the self-interaction of the collective electronic polarization with its own emitted field.Expand

Experiments show ultrastrong light-matter coupling in a terahertz (THz) metamaterial where the cyclotron transition of a high-mobility two-dimensional electron gas (2DEG) is coupled to the photonic modes of an array of electronic split-ring resonators.Expand

We develop a general theory of the quantum vacuum radiation generated by an arbitrary time modulation of the vacuum Rabi frequency of an intersubband transition in a doped quantum well system… Expand

This work theoretically investigates the optical response of a one-dimensional array of strongly nonlinear optical microcavities, and signatures of strong correlations are identified in the transmission spectrum of the system, as well as in the intensity correlations of the transmitted light.Expand

This work verifies the existence of the very strong coupling regime in magneto-optical measurements on a microcavity characterized by g/E_{B}≈0.64, showing that the average electron-hole separation of the upper polariton is significantly increased compared to the bare quantum well exciton Bohr radius.Expand

It is shown that, when the coupling between light andmatter becomes strong enough, this picture breaks down, and light and matter degrees of freedom totally decouple.Expand

The theory demonstrates the possibility of final-state stimulation for the scattering of intersubband polariton excitations in a microcavity-embedded two-dimensional electron gas, and predicts a quantum degenerate regime and lasing without electronic population inversion in an optical pumping configuration.Expand

The first complete quantum analysis of the Szilard engine is presented, and an analytic expression of the quantum-mechanical work performed by a quantum SZE containing an arbitrary number of molecules is derived.Expand

This work investigates a cavity quantum electrodynamic effect, where the alignment of two-dimensional freely rotating optical dipoles is driven by their collective coupling to the cavity field, and demonstrates that it exhibits a second order phase transition between a bunched state of isotropic orientations and a stretched one with all the dipoles aligned.Expand