Switchable Ultrastrong Coupling in Circuit QED
Borja Peropadre, P. Forn-Díaz, E. Solano, Juan José García‐Ripoll · Physical Review Letters · 2010
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 junctions which are directly connected to a closed (cavity) or open transmission line. In both cases the circuit induces a coupling that can be modulated in strength, reaching the so-called ultrastrong coupling regime in which the coupling is comparable to the qubit and photon frequencies. Furthermore, we suggest a wide set of applications for the introduced architectures.