Circuit QED in the Ultrastrong Coupling Regime Under Incoherent Excitations

Nowadays many people are well aware of quantum computers and the enormous resources employed by leading companies, such as Google inc. and IBM, to develop this new technology. The quantum computers designed by these companies are based on superconducting quantum circuits. The building blocks are superconducting artificial atoms, also known as superconducting qubits. The research activity studying superconducting quantum circuits in interaction with microwave photons is known as circuit quantum electrodynamics (QED). This topic is the analogous of cavity QED for superconductive circuits. Cavity QED studies the interaction between atoms or collective excitations in solid state systems and photons in regimes where the nonclassical properties of the electromagnetic field emerge.