New paper on Two-photon Quantum Rabi model

A new publication has appeared led by Dr. Pol Forn-Díaz on the theoretical implementation of the two-photon quantum Rabi model. A purely genuine, two-photon interaction is a very intriguing effect, and it is very difficult to find a system in nature that exhibits such phenomenon. In this work, which is a collaboration with the group of Prof. Solano at UPV-EHU in Bilbao, the team found a superconducting circuit which is described by a purely two-photon interaction. The work also investigated the very intriguing phenomenon of a spectral collapse, when the two-photon interaction exceeds a certain critical value and the spectrum of the systems becomes unbounded. The work appeared in Physical Review A. The full reference is Phys. Rev. A 97, 013851 (2018).

This circuit, consisting of a dc-SQUID and a flux qubit, implements the two-photon quantum Rabi model.