Ultrastrong coupling between light and matter has, in the past decade, transitioned from a
theoretical idea to an experimental reality. It is a new regime of quantum light–matter …

In the past 20 years, impressive progress has been made both experimentally and
theoretically in superconducting quantum circuits, which provide a platform for manipulating …

This article reviews theoretical methods developed in the last decade to understand cavity
quantum electrodynamics in the ultrastrong‐coupling regime, where the strength of the light …

We present and analyze a method where parametric (two-photon) driving of a cavity is used
to exponentially enhance the light-matter coupling in a generic cavity QED setup, with time …

The interaction between light and matter remains a central topic in modern physics despite
decades of intensive research. Coupling an isolated emitter to a single mode of the …

Electromagnetic fields possess zero point fluctuations which lead to observable effects such
as the Lamb shift and the Casimir effect. In the traditional quantum optics domain, these …

We study the scattering of individual photons by a two-level system ultrastrongly coupled to
a waveguide. The scattering is elastic for a broad range of couplings and can be described …

We show experimentally that a dc biased Josephson junction in series with a high-enough-
impedance microwave resonator emits antibunched photons. Our resonator is made of a …

Heisenberg's uncertainty principle implies that the quantum vacuum is not empty but
fluctuates. These fluctuations can be converted into radiation through nonadiabatic changes …

Starting from the paradigmatic spin-boson model (SBM), we investigate the static and
dynamical properties of a system of two distant two-level emitters coupled to a one …