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 recent theoretical and experimental advances in the fundamental
understanding and active control of quantum fluids of light in nonlinear optical systems. In …

We consider a system composed of a two-level system (ie, a qubit) and a harmonic oscillator
in the ultrastrong-coupling regime, where the coupling strength is comparable to the qubit …

There has been recent progress in understanding chaotic features in many-body quantum
systems. Motivated by the scrambling of information in black holes, it has been suggested …

We assess experimentally the suitability of coupled-transmission-line resonators for studies
of quantum phase transitions of light. We have measured devices with low photon hopping …

We generalize the dispersive theory of the Jaynes-Cummings model beyond the frequently
employed rotating-wave approximation (RWA) in the coupling between the two-level system …

Quantum entanglement, one of the defining features of quantum mechanics, has been
demonstrated in a variety of nonlinear spinlike systems. Quantum entanglement in linear …

We propose different designs of switchable coupling between a superconducting flux qubit
and a microwave transmission line. They are based on two or more loops of Josephson …

Josephson parametric amplifiers (JPA) are promising devices for applications in circuit
quantum electrodynamics and for studies on propagating quantum microwaves because of …

Decoherence due to contact with a hot environment typically restricts quantum phenomena
to the low temperature limit, k BT/ℏ ω≪ 1 (ℏ ω is the typical energy of the system). Here we …