Switchable ultrastrong coupling in circuit QED.
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.
Peropadre
B
B
Instituto de Física Fundamental, CSIC, Serrano 113-bis, 28006 Madrid, Spain.
Forn-Díaz
P
P
Solano
E
E
García-Ripoll
J J
JJ