title: Observation of cascaded two-photon-induced transitions between fluxoid states of a SQUID
abstract: We present evidence for transitions between fluxoid wells of a SQUID due to cascaded, two-photon processes. Such transitions are evidenced by an anomalous dependence on the transition rate from the one-photon resonant level within the initial well, which cannot be explained by previously observed macroscopic resonant tunneling. These two-photon processes may be a significant source of decoherence in SQUID qubits subject to microwave radiation.
authors.affiliation: Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, USA.
authors.initials: S
authors.lastname: Han
authors.initials: R
authors.lastname: Rouse
authors.initials: JE
authors.lastname: Lukens